Why Fluids Kill Polymers

Hi, my name is Joe McFadden. I’ve spent more than forty years as an engineer, educator, and investigator of failures. I’m offering this content to you, not as a textbook, but as a conversation—with failure itself, with history, and with lived experiences.

Based upon my lived experiences, I found that many failures, failures across many industries, were the result of the failure to incorporate a holistic approach during development.

Let me share the why behind this particular telling. Over the years, the more I’ve chased the why of things—why parts fail, why people do what they do, why the world works the way it does—the more I’ve found that every path leads back to the same place. Energy.

And not energy as some abstract idea, but something more specific: how everything stores energy, moves and manipulates it, and ultimately lets it go—how it dissipates. That thread runs through all of it. It’s how life evolved. It’s how we think—how our minds take in and process information. It’s how we act, how we live, and, in the end, how we pass. It’s the lived experience of you and me. It’s the lived experience of our ancestors, carried forward into us. And it’s every bit as true for the materials we choose and the systems we build—they answer to the same imperative we do.

Consider life itself. One of the most compelling theories of how life arose and grew more complex isn’t really about survival or replication at all—it’s about dissipation. The thinking runs from Schrödinger, yes the cat guy, Schrödinger’s question of what life is, through the work of Ilya Prigogine—the Belgian chemist who earned a Nobel Prize for showing how ordered structures can arise spontaneously in systems held far from equilibrium—and on into more recent thermodynamics. The idea is that complex, living systems may emerge precisely because they are so good at taking in energy and dissipating it, at hurrying the flow of energy from concentrated to spread-out. Life, in this view, is one of the universe’s most elegant ways of dissipating energy.

I’m actually in the middle of this right now. After getting pulled into the idea of dissipative systems—and Prigogine’s work, along with others—I picked up a book called Into the Cool: Energy Flow, Thermodynamics, and Life, by Eric Schneider and Dorion Sagan. Their argument is that the universe is relentlessly driven to break down gradients—differences in the concentration of energy—and that life is one of nature’s most effective ways of doing exactly that. Reading it has only deepened my conviction that this story, too, is at heart a story about energy.

And here’s the most beautiful irony of all. For something so fundamental—something that shapes how we evolved, how we think, how we live and how we pass—we still cannot say what energy actually is. Richard Feynman pointed this out plainly: in all of physics, we have no real definition of what energy is. We know how to count it, measure it, and track it as it changes form, and we know that it’s always conserved. But what it is, at bottom, we do not know. We understand energy entirely by what it does, never by what it is. So all roads lead back to energy. And energy is the one thing we still can’t say we understand.

So I went back to my earlier work on this subject—work that had already brushed up against this idea—and I felt it was time to tell the story properly, through the lens of energy: how it’s stored, how it’s moved, and how it’s let go. Because once you see that everything bends toward energy and its dissipation, what we call environmental stress cracking stops looking like a strange exception and starts looking like one more expression of the rule.

This brings me to today’s discussion, of compatibility of plastic components in the real world.

Ok, let’s start.

How Fluids Kill Polymers

The Energy-Mediated Fluid Cracking Story — An Audiobook Conversation

Introduction: The Mystery of Energy-Mediated Fluid Cracking

Hello. Joe McFadden here. Welcome to what I’m calling my “holistic audiobook” on one of the most fascinating, most frustrating, and most misunderstood failure modes in polymer engineering.

Let me tell you about one of the most insidious, most seemingly impossible failure modes in polymer engineering: what we traditionally call environmental stress cracking, or ESC. But we’re going to talk about why I think we need a new name—Energy-Mediated Fluid Cracking, or EMFC for short—and why the old name actually obscures what’s really happening. We’re going to understand this phenomenon at a deep level, centering the energy, the thermodynamics, and the molecular interactions that make fluids such deadly agents for polymers.

Picture this: You’ve got a polyethylene storage tank. It’s been holding water under pressure for five years. No problems. The stress analysis shows it’s well within safe limits. The material is chemically resistant to water. Everything should be fine.

Then someone fills it with a detergent solution. Not a strong acid, not a solvent that dissolves polyethylene, just a mild detergent. And within 48 hours, the tank cracks. Catastrophically. Thousands of gallons of fluid on the floor.

Or this: A polycarbonate component in a medical device. Carefully designed, thoroughly tested, performing beautifully in service. Then a technician wipes it with isopropanol during routine cleaning—a procedure that’s been done hundreds of times. And it cracks. Right there, right then. An audible snap, a visible fracture, sudden failure.

What’s going on? The stress didn’t change. The detergent doesn’t dissolve polyethylene. The alcohol doesn’t dissolve polycarbonate. So why do these materials suddenly fail when they contact these fluids?

The answer lies in understanding something fundamental about cracks: they’re not just geometric features, they’re surfaces. And surfaces have energy. And fluids can change that energy. And when they do, they change everything about how cracks grow.

This is the story of energy-mediated fluid cracking through the lens of surface energy and thermodynamics. We’re going to understand why certain fluids cause catastrophic failures, why the specific polymer-fluid pair matters so much, and—here’s where it gets really interesting—why the way you apply the fluid matters as much as what the fluid is.

Because I’m going to share some field observations that reveal complexities you won’t find in textbooks. Things like: why wiping a part with solvent can be more damaging than immersing it. Why repeated brief exposures can be worse than continuous long exposure. Why sometimes heating a part while keeping it wet actually protects it from damage.

These aren’t paradoxes—they’re thermodynamics and kinetics playing out in ways that surprise us if we’re not thinking carefully about what’s really happening.

So let’s dive in. We’re going to talk about Griffith and energy balances, about surface energy and why it matters, about capillary action and fluid penetration, and about some real-world forensic work that reveals how complex this behavior really is.

By the end, you’re going to understand energy-mediated fluid cracking not as some mysterious material defect but as a predictable consequence of thermodynamic principles. And once you understand it, you can design against it, test for it, and prevent it.

Let’s start with why we need a new name for this phenomenon.

Why We Need a New Name: From ESC to EMFC

Okay, so first things first. Why am I calling this “Energy-Mediated Fluid Cracking” instead of the traditional “environmental stress cracking”?

It’s not just semantics. Names matter. The terminology we use shapes how we think about problems. And I’ve come to believe that “environmental stress cracking” is actually a problematic name that obscures the fundamental physics.

First, “environmental” is vague. What does it even mean? The ambient environment? Temperature and humidity? Chemical exposure? All of the above?

In practice, what we’re really talking about is fluid exposure. Specific liquids or sometimes vapors coming into contact with the polymer. Not just “the environment” broadly, but particular chemical species that interact with the polymer in specific ways.

Water is an environment. Air is an environment. But water causes this failure mode in nylon while doing almost nothing to polyethylene. Air generally doesn’t cause it at all. So “environmental” is too broad, too nonspecific.

If we say “fluid cracking,” we’re immediately more precise. We’re pointing attention to the right place: which fluids, which polymers, what’s the interaction?

Second, we’ve got “stress” appearing twice—once explicitly in “stress cracking” and implicitly in the fact that we’re talking about stressed components. But here’s the thing: stress is necessary but it’s not the primary variable that changes.

Think about it. You’ve got a component under stress. It’s carrying load. Let’s say twenty megapascals—a nice moderate stress level, well within the design limits, nothing dramatic. And this component sits there in air for years. No problem. The stress hasn’t caused failure.

Now that same component, same stress level, contacts a particular fluid. And within hours or days, it cracks. Catastrophically.

What changed? The stress didn’t change. It’s still twenty megapascals. The mechanical loading situation is identical.

What changed is the energy landscape. The thermodynamic balance that determines whether crack growth is favorable or not. And that change was mediated by the fluid.

So emphasizing “stress” twice in the name kind of misses the point. Yes, stress is necessary—you need tensile stress to drive crack opening. But stress alone wasn’t causing failure. The fluid fundamentally altered what stress level is safe versus dangerous.

Third, and this is the big one: the traditional name tells us nothing about the mechanism. It’s purely descriptive. “Under stress, in an environment, cracking happens.” Okay, but why? What’s the physical process?

Compare this to other well-named phenomena. “Stress corrosion cracking”—okay, corrosion is the mechanism, it’s an electrochemical process, we know what’s happening. “Hydrogen embrittlement”—hydrogen is entering the material and affecting crack growth, mechanism identified.

But “environmental stress cracking”? It just describes the conditions—stress plus environment—without explaining the causation. It’s like naming a disease “sick person syndrome.” Descriptive but not explanatory.

So here’s what I’m proposing: Energy-Mediated Fluid Cracking. EMFC for short.

“Energy-Mediated” puts the mechanism front and center. This is about energy. Specifically, it’s about how fluids alter the energy balance that governs fracture. They reduce the energy cost of creating crack surfaces, which shifts the thermodynamic equilibrium toward crack growth. Energy is the lens through which we understand this phenomenon.

When you hear “energy-mediated,” you’re immediately thinking thermodynamics. You’re thinking energy balance, energy barriers, energy landscapes. That’s exactly the right mental framework.

“Fluid” specifies the agent. Not “environment” vaguely, but fluids specifically. This directs attention to the critical question: which fluids interact with which polymers to create the energy change we’re talking about?

“Cracking” is the outcome. We’re talking about crack propagation, fracture, material separation. Clear and specific.

So: Energy-Mediated Fluid Cracking. The mechanism, the agent, the result. All in the name.

Why this matters: the name shapes how we think about the problem. If we call it “stress cracking,” we focus on stress reduction. And yes, reducing stress helps—I’m not saying it doesn’t. But we might miss that material selection based on surface energy properties is equally important. We might miss that the specific fluid matters enormously.

If we call it “environmental” cracking, we might think broadly about “harsh environments” rather than specifically about molecular interactions between fluids and polymers.

But if we call it “energy-mediated fluid cracking,” we’re immediately asking the right questions:

•     What’s the surface energy of this polymer?

•     How much does this fluid reduce that surface energy?

•     What’s the energy balance—is crack growth favorable?

•     Can we modify the energy landscape through material choice, coatings, barriers?

The name guides the thinking. The thinking guides the solution.

So throughout this audiobook, I’m going to use EMFC when I’m talking about the phenomenon mechanistically. I’ll still say ESC when I’m referencing historical literature or established test standards—we can’t just ignore decades of accumulated knowledge. But conceptually, we’re thinking EMFC.

Energy-mediated. That’s the key. The fluids are mediating an energy change that enables crack growth.

Okay, with that established, let’s build the foundation. Let’s talk about Griffith.

Part One: Griffith’s Gift—Understanding Fracture Through Energy

The Paradox That Started It All

In the early 1920s, there was a problem. A big problem. Engineers could calculate, from basic atomic bond strengths, how strong materials should be. The theoretical strength—the stress required to literally rip atoms apart—was enormous. Materials should be incredibly strong.

But they weren’t. Glass, in particular, was failing at stresses sometimes 100 times lower than theoretical strength predicted. A hundred times! That’s not a rounding error. That’s a fundamental disconnect between theory and reality.

Allan Griffith, working on this problem, had a crucial insight. He realized that everyone was asking the wrong question. They were asking “how much stress does it take to break bonds?” But Griffith asked a different question: “What’s the energy balance during crack formation?”

The Energy Balance Insight

Here’s Griffith’s logic, and it’s beautiful in its simplicity.

When a crack forms, or when an existing crack grows, two things happen energetically.

First, you create surfaces. A crack has two faces—upper and lower. Those faces are new surfaces that didn’t exist before. Creating surfaces requires energy. Why? Because molecules at a surface are in a higher energy state than molecules in the bulk. They’re missing neighbors on one side. They have unsatisfied bonds, unsatisfied molecular interactions. That costs energy.

We call that energy cost “surface energy,” denoted by the Greek letter gamma. It’s measured in energy per unit area—something like millijoules per square meter. Every material has a characteristic surface energy. For polymers, it’s typically thirty to fifty millijoules per square meter.

So if you extend a crack by a little bit—call it d-a—you create new surface area. For a crack of unit thickness, you’re creating two times d-a of new surface on each face, times two faces, so four times d-a total. The energy required is four gamma times d-a.

Second, you release strain energy. The material around a crack is under stress. That stress stores elastic energy, like a compressed spring stores energy. When the crack extends, material that was previously loaded becomes unloaded—it’s now inside the crack, stress-free. The strain energy that was stored in that material is released.

For a crack in an infinite plate under stress sigma, the strain energy released when the crack extends by d-a is pi times sigma squared times a, divided by E, all times d-a—where E is the elastic modulus and a is the crack half-length.

The Criterion for Crack Growth

Griffith said: the crack grows when the energy released equals or exceeds the energy required. When the strain energy you get back is enough to pay for creating the new surfaces.

This gives you a critical stress:

Sigma-c equals the square root of two E gamma, over pi a.

Look at what this equation tells us. Three profound insights:

One: Fracture stress depends on crack size. Bigger cracks fail at lower stress. That’s the square root of a in the denominator. This explained why real materials with flaws failed at stresses far below theoretical strength—the flaws acted as crack initiators.

Two: Fracture stress depends on surface energy. That’s the gamma under the square root. Higher surface energy means higher fracture resistance. The material is harder to crack because creating surfaces is more expensive energetically.

Three: Stiffer materials resist fracture better. That’s the E under the square root. Stiffer materials store more strain energy for a given stress, so they have more energy available to drive crack growth, but it turns out that relationship is favorable overall.

But for us, for understanding EMFC, insight number two is the critical one. Surface energy directly controls fracture resistance.

And here’s the key: if you reduce surface energy, you reduce fracture resistance.

That’s the whole game. That’s why EMFC happens. Fluids reduce surface energy, making it easier—energetically cheaper—to create cracks.

From Cracks to Crazes

Now, Griffith was working with glass—brittle, elastic materials. But the framework extends beautifully to polymers and crazing.

A craze isn’t quite a crack. It’s not empty space. It’s a network of polymer fibrils bridging across voids. About 50% void, 50% stretched polymer. But those voids represent surfaces—polymer-air interfaces. Creating a craze requires creating all that void surface area.

The total energy to create a craze includes not just surface energy but also the work to stretch and orient polymer chains into fibrils, and the energy to partially disentangle chains at the craze tip. It’s more complex than a clean brittle crack.

But surface energy remains a critical component. And reducing surface energy still lowers the energy barrier to craze formation and growth. The fundamental principle holds.

Part Two: How Fluids Reduce Surface Energy

Okay, so surface energy matters. But how do fluids reduce it? What’s the physical mechanism?

The Nature of Surfaces

First, let’s understand what surface energy is, physically. Why do surfaces have excess energy at all?

Think about a molecule in the bulk of a material. It’s surrounded by neighbors in all directions—left, right, up, down, forward, back. All those neighbors are interacting with it through various forces: van der Waals forces, dipole interactions, maybe hydrogen bonds. The molecule is in a satisfied state, energetically. All its interaction sites are engaged.

Now think about a molecule at a surface. It’s still got neighbors on the bulk side, but on the surface side? Nothing. Air. Vacuum. Whatever, but not more material. That molecule has unsatisfied interaction sites. It’s in a higher energy state than the bulk molecules.

That excess energy, summed over all the surface molecules and divided by surface area, is the surface energy. It’s literally the energy cost of having a surface instead of bulk.

For a polymer-air interface, that surface energy reflects the unsatisfied molecular interactions at the polymer surface. Typical values: thirty to fifty millijoules per square meter for most common polymers.

What Happens When Fluid Replaces Air

When a fluid contacts that polymer surface—gets into a crack, wets a craze—it replaces the polymer-air interface with a polymer-fluid interface.

The energy of that new interface depends on how well the fluid molecules interact with the polymer molecules. If they interact strongly—if there’s good adhesion between polymer and fluid—the interface has low energy. The polymer surface molecules are satisfied, or at least more satisfied than they were facing air.

The thermodynamic relationship is the Dupré equation:

The work of adhesion, W-A, equals gamma-P-A, plus gamma-F-A, minus gamma-P-F.

Where W-A is the work of adhesion—the energy required to separate the polymer-fluid interface; gamma-P-A is the polymer-air surface energy; gamma-F-A is the fluid-air surface tension, the fluid’s own surface energy; and gamma-P-F is the polymer-fluid interfacial energy.

Rearranging this, the reduction in surface energy when fluid replaces air is:

Delta gamma equals gamma-P-A minus gamma-P-F, which is the same as W-A minus gamma-F-A.

This simple equation tells us everything about which fluids will be aggressive EMFC agents and which won’t.

The Two Factors That Matter

Factor One: Work of Adhesion, W-A. How strongly does the fluid stick to the polymer? Strong adhesion means high W-A, which means large surface energy reduction.

What creates strong adhesion? Molecular similarity. “Like dissolves like,” the old chemistry saying, applies here. Fluids with molecular structures similar to the polymer create strong interactions.

Polyethylene is a nonpolar hydrocarbon chain. So are many oils, greases, and detergents (which contain long hydrocarbon chains). These fluids adhere well to polyethylene, creating high W-A, causing large surface energy reduction.

Polycarbonate is an aromatic ester polymer. Organic solvents with aromatic rings or ester groups—things like toluene, acetone, esters—interact strongly with PC, creating high W-A.

Water? Water is highly polar. It doesn’t interact well with nonpolar polymers like PE or PP. Low W-A, minimal surface energy reduction, little EMFC effect. But water does interact with polar polymers like nylon (through hydrogen bonding), so water can cause EMFC in nylon even though it’s harmless to PE.

The specificity of EMFC comes from this molecular interaction specificity. Particular fluids attack particular polymers based on molecular compatibility.

Factor Two: Fluid Surface Tension, gamma-F-A. The fluid’s own surface tension matters too. Lower surface tension fluids are generally more effective.

Water has high surface tension—about seventy-two millijoules per square meter. Organic solvents have much lower surface tensions, twenty to forty millijoules per square meter. This is part of why organic solvents are more aggressive EMFC agents than water for most polymers.

But here’s where it gets really interesting: surfactants. Surface-active agents, like the detergents in that polyethylene tank story. Surfactants are molecules with one end that likes water and one end that likes oil. They concentrate at interfaces and dramatically lower surface tension.

A detergent solution might have surface tension below thirty millijoules per square meter—less than half of pure water. And detergents often have long hydrocarbon chains that interact favorably with polymers. So they achieve both high W-A (good adhesion) and low gamma-F-A (low fluid surface tension). Double whammy. Extremely effective EMFC agents.

This is why detergents, soaps, cleaning solutions—mild, innocuous-seeming fluids—are so dangerous to stressed polymers. They’re optimized, almost by accident, to reduce surface energy dramatically.

Some Quantitative Examples

Let me give you numbers to make this concrete.

•     Polyethylene to air: gamma-P-A is about thirty-five millijoules per square meter.

•     Polyethylene to water: gamma-P-F is about thirty millijoules per square meter—a small reduction; water doesn’t wet PE well.

•     Polyethylene to detergent solution: gamma-P-F is about fifteen to twenty millijoules per square meter—a huge reduction; detergent lowers surface tension and wets PE.

•     Polyethylene to oil: gamma-P-F is about five to ten millijoules per square meter—a massive reduction; oil is very similar to PE molecularly.

So a detergent solution reduces surface energy by forty to fifty percent. An oil might reduce it by seventy to eighty percent. These are enormous changes in the energy balance.

•     Polycarbonate to air: gamma-P-A is about forty-two millijoules per square meter.

•     Polycarbonate to water: gamma-P-F is about thirty-eight millijoules per square meter—a small reduction; water barely affects PC.

•     Polycarbonate to isopropanol: gamma-P-F is about twenty-five millijoules per square meter—a moderate reduction; alcohol partially wets PC.

•     Polycarbonate to acetone: gamma-P-F is about ten millijoules per square meter—a large reduction; acetone strongly interacts with PC.

Acetone reduces PC surface energy by seventy-five percent. That’s why a drop of acetone on stressed PC can cause instant cracking. The energy barrier to crack growth just collapsed.

Part Three: What Surface Energy Reduction Does

Now we understand that fluids reduce surface energy. Let’s understand what that reduction does to crack growth.

The Initiation Threshold Drops

Remember the Griffith equation: sigma-c equals the square root of two E gamma over pi a. Critical stress is proportional to the square root of surface energy. Reduce surface energy, and you reduce the stress required for crack growth.

Let’s work through an example. Suppose you’ve got a polymer part under stress—let’s say sigma equals twenty megapascals. And suppose in air, the critical stress for crack growth from existing flaws is twenty-five megapascals. You’re safe. Twenty is less than twenty-five. No crack growth.

Now introduce a fluid that reduces surface energy by 50%. The new critical stress is:

Sigma-c in fluid equals sigma-c in air, times the square root of zero point five, which is about zero point seven oh seven, times twenty-five megapascals—roughly seventeen point seven megapascals.

Now your applied stress, twenty megapascals, exceeds the critical stress, seventeen point seven megapascals. The crack that was stable in air becomes unstable in the fluid environment. Crack growth begins.

The fluid didn’t add stress. It didn’t mechanically weaken the material. It simply changed the thermodynamic stability criterion. What was safe became unsafe.

This is why EMFC is so insidious. The part was fine. The stress didn’t change. But the environment changed, and suddenly fracture becomes thermodynamically favorable.

No Surface Is Perfect

Before we talk about how an existing crack grows, let’s back up and ask a basic question: where does that existing crack come from? Because here’s the thing—no surface is perfect. Not one. Every real surface, on every real part, is covered in microscopic flaws.

Think back to Griffith. Remember how glass failed at stresses a hundred times below its theoretical strength? That gap exists precisely because real materials are riddled with tiny pre-existing cracks. The theoretical strength assumes a perfect, flawless solid. Reality never hands you one.

So where do these flaws come from? Everywhere. Processing is a big source—molding, extrusion, and machining leave behind microscopic voids, weld lines, frozen-in stresses, gate marks, and fine surface scratches. Handling adds more: every time a part is touched, wiped, or set down, it picks up abrasion marks. And then there’s the material itself—at the molecular scale, polymers have density fluctuations, chain ends, additive and filler particles, and, in semicrystalline plastics, boundaries between spherulites. Every one of those is a potential crack starter.

How big are these flaws? They span an enormous range. The smallest reside down at the nanometer scale—a few millionths of a millimeter. The ones that matter most for cracking are usually bigger, somewhere from a fraction of a micrometer up to tens, even hundreds, of micrometers. In fact, engineers often model a polymer as if it contains a built-in “inherent flaw” on the order of tens of micrometers—small enough to be invisible to the eye, large enough to be dangerous.

Here’s the key point: you don’t have to create a crack to have a crack. You already have thousands of them, everywhere, on every surface, before the part ever goes into service.

Now here’s something people tend to forget: air is a fluid. In physics, a fluid is anything that flows—and that includes gases, not just liquids. So a part sitting quietly “in air” is actually sitting in a fluid environment. And air is never just air. It carries water vapor—humidity—along with oxygen and whatever else happens to be floating around.

And over time, that air, and the water it carries, works its way into those microscopic fissures. The gaps are so small that capillary forces draw the vapor in and pull it right down to the crack tip. In the very smallest cracks, water vapor can even condense into liquid water when the surrounding air is nowhere near saturated—a quirk of physics that shows up specifically in nanoscale gaps. The crack, in effect, wicks moisture straight out of the air.

And here’s a detail worth pausing on, because it ties the whole story together: that capillary pull—that wicking—isn’t some separate force. It’s surface energy again. A liquid is drawn into a tiny gap because moving in lowers the total energy of the system: it trades a high-energy solid-and-air interface for a lower-energy solid-and-liquid one, and the liquid spreads to wet the walls. Whether a fluid wicks in at all comes down to whether it wets the surface—and that is set by the very same balance of surface energies we’ve been discussing. The narrower the gap, the stronger the pull, which is why the smallest cracks, down at the nanometer scale, draw fluid in most fiercely of all.

So surface energy is doing double duty here. It decides whether the fluid can even reach the crack tip—the delivery—and then it decides whether the crack will grow once the fluid arrives—the damage. Same physics at both ends of the process. All roads, again, lead back to energy.

So that “existing crack” we’re about to discuss? It was never truly empty. It was never sitting in a perfect vacuum. Its surfaces are already wetted—by air, by adsorbed water, by whatever the part has been breathing in. The energy balance at that crack tip is already a polymer-to-humid-air balance, not a polymer-to-nothing balance. It’s just a slow, mild version of the very same process we’ve been describing. Introduce a more aggressive fluid, and you don’t start the process—you pour fuel on a fire that’s already quietly smoldering.

Crack Growth Accelerates

For an existing crack that’s already growing, surface energy reduction affects growth rate. Crack growth rate typically follows some power law relationship between driving force and resistance:

The crack-growth rate, d-a by d-t, equals A times the quantity G minus G-c, raised to the power n.

Where G is the energy release rate (the driving force), G-c is the critical energy release rate—the resistance, related to surface energy by G-c equals two gamma—and n is some exponent typically between two and four.

When you reduce G-c (by reducing gamma), the difference, G minus G-c, increases. And because of that power-law relationship, crack growth rate can increase by factors of ten, a hundred, even more for modest reductions in surface energy.

A crack that was growing slowly, maybe a few micrometers per day in air, might grow at millimeters per hour in an aggressive fluid. That’s the difference between a crack that takes years to become critical and a crack that causes failure in hours.

The Positive Feedback Loop

And here’s where it gets really dangerous: crack growth and fluid penetration create a positive feedback loop.

•     Step 1: You’ve got a stressed part with some small crazes or surface flaws. In air, they’re stable or growing very slowly.

•     Step 2: The part contacts an EMFC-active fluid. The fluid wets the external surface.

•     Step 3: Capillary forces pull fluid into the craze void networks. Those voids are small—nanometers to micrometers—so capillary pressures are enormous. Fluid penetrates rapidly, driven by those capillary forces.

•     Step 4: Fluid reaches the craze tips—the active growth zones. Surface energy drops at those critical locations.

•     Step 5: With reduced surface energy, crazes grow faster. They widen (more void formation) and lengthen (advancing into bulk material). This creates more void space, more pathways.

•     Step 6: The enlarged voids provide even better fluid access. More fluid penetrates deeper. More craze tips get wetted.

•     Step 7: Back to Step 5, but now with even more surface area wetted, even more crack tips advancing.

This is self-accelerating. It’s a runaway process. Once it starts, it feeds itself, getting faster and faster until something breaks.

This positive feedback explains the catastrophic nature of EMFC failures. They’re not gradual. They’re not linear. They accelerate. The material doesn’t slowly degrade—it suddenly, rapidly fails once the feedback loop gets going.

Your Insight: Depth and Length

And here’s where your insight about depth and length comes in, and it’s spot-on.

Consider a craze that’s reached some stable configuration in air. It has a certain depth into the material, a certain length along the stress direction. This configuration represents an energy balance: strain energy released equals surface energy created.

Now introduce fluid that reduces surface energy by, say, 50%. The existing configuration is no longer at equilibrium. You’ve reduced the energy cost per unit surface area, but the strain energy released hasn’t changed. The equation is out of balance.

To restore balance, you need more surface area. How do you get more surface area? The craze deepens—it advances further into the material, creating more void volume, more fibril surface area, more interfaces. The craze lengthens—it extends longer in the stress direction, creating more craze length, more total area. And typically you get both deepening and lengthening, because both create the additional surface needed to balance the energy equation.

Quantitatively, if surface energy drops by half, the equilibrium surface area must double (at constant stress). So a craze that was depth d and length l might grow to depth root-two times d and length root-two times l, because area scales as d times l, and root two times root two equals two.

This is why fluids don’t just initiate cracks—they actively drive crack growth to greater depths and lengths. The thermodynamic balance demands it.

Part Four: The Surprising Complexity of Real-World Exposure

Now here’s where theory meets practice, and practice reveals complexities that theory alone wouldn’t predict. I’m going to share some field observations—forensic work, troubleshooting, real failure investigations—that show how energy-mediated fluid cracking behaves in service conditions. And some of these behaviors are counterintuitive until you understand what’s really going on.

The Wet Storage Paradox

Here’s an observation from troubleshooting PC and PC/ABS electronic housings with assembly-induced stress.

Wipe and dry: Take the device, wipe it with solvent-saturated cloth, let it dry. Repeat daily. Result: cracks develop within weeks.

Wet storage: Take an identical device, wrap it in a wet wipe soaked with the same solvent, seal it in a bag, store at forty degrees Celsius for forty-eight hours. Result: some surface damage, stress whitening, but no through-cracks. Device still functional.

Wait—what? The wet storage exposes the part to fluid continuously for 48 hours at elevated temperature. The daily wiping exposes it to fluid for seconds per day at ambient temperature. The wet storage should be more aggressive, right? Wrong. And here’s why.

What happens during wet storage: in the first few minutes to hours, fluid penetrates surface-connected flaws and crazes. Surface energy drops. Initial crack growth begins. But simultaneously, several protective mechanisms activate.

Plasticization: The fluid plasticizes the surface layers. Polymer chains gain mobility. This allows stress relaxation—the material creeps slightly, redistributing stress from peak values to surrounding regions. Peak stress decreases over time.

Swelling: If the fluid causes even modest swelling (volume expansion of the polymer), the swollen surface layers are constrained by the unswollen interior. This creates compressive stresses at the surface—compressive stress directly counteracts the tensile stress driving crack growth.

Equilibration: After hours to days at forty degrees Celsius, the system reaches equilibrium. Cracks have grown to some depth where energy balance is satisfied. Fluid has penetrated, stress has relaxed, and further crack growth stops because the driving force (reduced by relaxation) no longer exceeds the resistance (reduced by surface energy, but now at equilibrium).

The damage stabilizes. Yes, there are crazes. Yes, there’s stress whitening. But the crack depth is only tens or hundreds of micrometers—not enough to cause failure in a part with millimeter-scale walls.

What happens with cyclic wiping is different. Day 1: Fluid applied. Penetrates surface flaws. Surface energy drops. Crack growth begins. But before equilibration, the fluid evaporates. Surface dries. Surface energy partially recovers. Stress relaxation limited because exposure time was brief.

Day 2: Fresh fluid applied to an already-damaged surface. Fluid penetrates to previous crack depths rapidly (pathways already open) and extends deeper. Surface energy drops at new, deeper locations. Crack grows from the previous front. Dries again.

Days three through thirty: Each cycle advances damage incrementally deeper. Each fresh application re-activates surface energy reduction at progressively deeper crack fronts. The system never reaches equilibrium because you keep refreshing the fluid at new locations. After thirty cycles, cracks have grown one hundred to two hundred micrometers or more. Critical crack depth is reached. Component fails.

The cyclic nature prevents the protective equilibration that occurs in continuous immersion. Each application is a fresh attack. Stress relaxation doesn’t help because stress returns during the dry period. The system can’t settle into a stable state.

Why does elevated temperature (forty degrees Celsius) during wet storage actually help? Because it accelerates the protective mechanisms more than the damage mechanisms. At forty degrees Celsius: stress relaxation is five to ten times faster (exponential temperature dependence); plasticization effects develop faster and penetrate deeper; the system reaches equilibrium quickly—hours instead of days; and swelling effects may be enhanced, creating stronger protective compression.

The race between crack growth and stress relaxation/equilibration is won by the protective mechanisms at elevated temperature with continuous exposure. By the time the system equilibrates, cracks haven’t grown critically. But at ambient temperature with cyclic exposure, protective mechanisms never get a chance to win. Each cycle is too brief for relaxation, and cycles repeat before equilibration occurs.

The Acetone Immersion versus Swab Story

Here’s another observation from field testing. Two identical PC/ABS devices with assembly stress.

Device 1—Immersion: Complete device dunked in acetone for 30 seconds, removed, dried, inspected. Result: Surface crazing visible, stress whitening in high-stress regions, but no through-cracks. Device functional.

Device 2—Swab test: Cotton swab saturated with acetone, applied to a corner region where FEA showed a stress concentration of twenty-five megapascals. Brief application, maybe five seconds. Result: Audible crack—snap!—visible fracture propagating from the corner within seconds.

Same fluid, same part, but vastly different outcomes. What gives?

Immersion (global exposure): When you immerse the whole device, you expose the entire surface uniformly. Acetone plasticizes everywhere simultaneously. Before significant crack growth can occur at any specific location, stress relaxation begins throughout the stressed volume. Any crack initiation is distributed among many potential sites—every stress concentration, every flaw. Surface energy reduction is uniform, but so is stress relief. No single location experiences optimal conditions for crack growth before protective mechanisms engage. The result: distributed superficial damage, but no single crack achieves critical size.

Swab test (localized application): The swab delivers fluid specifically to one location—the highest stress region, identified by analysis. This creates optimal worst-case conditions: maximum stress (twenty-five megapascals at the stress concentration); fresh, concentrated fluid (saturated swab); no time for stress relaxation (application duration seconds); all the aggressive factors without any protective factors.

It’s like the difference between heating an entire glass beaker slowly (uniform thermal stress, no fracture) versus touching one spot with an ice cube (localized thermal shock, instant fracture).

The localized application is dramatically more aggressive because it combines maximum stress with maximum chemical attack without allowing protective mechanisms to activate. The lesson: how you apply fluid matters as much as what the fluid is. Distributed exposure can be less damaging than localized exposure because protective mechanisms have time to engage globally before damage localizes.

Part Five: The Dance Between Damage and Protection

What these field observations reveal is something subtle: EMFC isn’t just about crack growth. It’s about a competition between damage mechanisms (crack growth, fibril breakdown) and protective mechanisms (stress relaxation, equilibration, possibly swelling-induced compression).

The Time Scales Matter

Different processes happen at different rates.

•     Very fast (seconds to minutes): fluid wetting of external surfaces; initial capillary penetration into surface-connected voids; surface energy reduction at fluid-wetted interfaces.

•     Fast (minutes to hours): deeper capillary penetration into crack networks; initial plasticization of surface layers; beginning of stress relaxation in plasticized regions.

•     Moderate (hours to days): full plasticization penetration to relevant depths; substantial stress relaxation throughout the stressed volume; the system approaches equilibrium; swelling effects fully develop (if swelling occurs).

•     Slow (days to weeks): complete equilibration at given temperature; potential fluid degradation or compositional changes; long-term creep and stress redistribution.

The outcome depends on which processes dominate in the available time. Short exposure (seconds to minutes): damage mechanisms dominate. Surface energy reduction is fast. Crack growth begins immediately. Protective mechanisms haven’t engaged. Most aggressive scenario. Intermediate exposure (hours): competition between damage and protection. Depends on temperature, fluid effectiveness, stress level, material properties. Could go either way. Long exposure (days): if exposure is continuous, protective mechanisms can win and the system equilibrates; if exposure is cyclic (fresh fluid repeatedly applied), damage dominates because equilibration never occurs.

The Role of Stress Relaxation

Stress relaxation deserves special attention because it’s the primary protective mechanism.

Polymers are viscoelastic. Under sustained load, they creep—deform gradually over time. This creep redistributes stress from peak locations (stress concentrations) to broader regions.

The relaxation time depends on temperature and molecular mobility. At room temperature, relaxation in an unplasticized glassy polymer might take weeks. At forty degrees Celsius, maybe days. In a plasticized polymer (one that’s absorbed fluid), relaxation accelerates dramatically—maybe hours or even minutes.

This is why wet storage at forty degrees Celsius can be protective. The combination of temperature and plasticization creates fast relaxation. Stress drops from, say, twenty-five megapascals to fifteen megapascals within hours. At fifteen megapascals, even with reduced surface energy, crack growth rate is much slower. Equilibrium is reached before critical crack depth.

But cyclic exposure at ambient temperature doesn’t allow this. Each exposure is too brief for meaningful relaxation. And during drying, elastic recovery restores stress. The next cycle starts again at high stress.

Materials with faster intrinsic stress relaxation behavior resist cyclic EMFC better, even if their crack growth rates in fluid are similar to other materials. The ability to “relax away” the driving force provides margin that materials without good relaxation don’t have.

The Swelling Effect

We’ve mentioned swelling, but let’s think about it more carefully.

If a fluid causes polymer to swell—increase in volume from fluid absorption—the swollen region wants to expand. But if swelling is localized to surface layers (fluid hasn’t penetrated deeply), the unswollen interior constrains the swollen surface. This constraint creates compressive stress at the surface.

Compressive stress opposes tensile stress. If you’ve got twenty megapascals of tensile stress from applied loads, and swelling creates ten megapascals of compressive stress, the net tensile stress drops to ten megapascals. Lower stress means lower crack driving force.

This is a protective effect. Materials that swell moderately in EMFC-active fluids might actually gain some protection from swelling-induced compression, even though swelling also indicates fluid absorption and plasticization.

The magnitude of this effect depends on how much swelling occurs (higher swelling means more compression), how localized the swelling is (surface swelling only gives strong constraint; bulk swelling gives no constraint), and the modulus of swollen versus unswollen material. This is subtle stuff, difficult to predict without experiments, but it’s part of the complex competition between damage and protection.

Part Six: What This Means for Testing and Design

These observations—the paradoxes, the complexities, the competitions—have profound implications for how we test materials and design components.

Standard Tests May Mislead

The typical EMFC test protocol: immerse stressed specimen in fluid, measure time to failure. This test captures fluid aggressiveness under one specific condition—continuous immersion.

But if service conditions involve cyclic exposure—cleaning, wiping, intermittent splashing—continuous immersion tests may significantly overestimate service life. Cyclic field exposure can be far more aggressive than lab immersion.

Recommendation: Supplement immersion tests with cyclic exposure protocols. Apply fluid, allow drying, repeat. See if failures occur that immersion tests don’t reveal. Also consider localized application tests—swab tests, drop tests—especially for components where fluid contact is localized in service. These “worst case” tests may reveal vulnerabilities that global immersion misses.

The Value of Forensic Testing

Using FEA to identify high-stress locations, then deliberately attacking those locations with swabs or localized application, is powerful forensic work. You’re creating optimal conditions for failure: maximum stress (from FEA); maximum chemical attack (fresh, concentrated fluid); minimum protection (brief exposure, no relaxation time).

If the part survives this worst-case testing, it’s probably safe in milder service conditions. If it fails, you’ve identified the critical location and can redesign (reduce stress) or change materials. This is like destructive testing in metallurgy—you’re deliberately failing parts to understand failure mechanisms and margins.

Design Strategies That Work

Understanding the mechanisms suggests design strategies.

•     Reduce peak stress: always. Lower stress reduces crack driving force and provides margin even when surface energy is reduced. Use FEA to find and mitigate stress concentrations. Generous radii, smooth transitions, avoid sharp corners.

•     Design for drainage: if components contact fluids, design so fluids drain quickly and completely. Don’t let fluids pool or get trapped in crevices near high-stress regions. Rapid drainage limits exposure time, reduces damage per cycle.

•     Seal critical regions: if possible, isolate high-stress regions from fluid contact. Gaskets, O-rings, barriers, conformal coatings—physical separation can be highly effective.

•     Choose materials wisely: not just chemical resistance (immersion resistance) but also stress relaxation behavior. Materials that relax quickly may better resist cyclic EMFC. Impact-modified polymers often have better relaxation than rigid grades.

•     Minimize residual stress: processing-induced stress adds to service stress. High residual stress leaves less margin. Optimize processing—slow cooling, lower packing pressure, proper gate design. Consider annealing to relieve stress.

•     Rethink assembly: snap-fits and press-fits create sustained stress. Can you redesign to eliminate sustained stress? Threaded fasteners, adhesives, alternative geometries?

Service and Maintenance Matters

Sometimes the solution isn’t in design or materials—it’s in how the part is used and maintained.

Cleaning protocols: if failures correlate with cleaning, review protocols critically. Can you use a different cleaner (one that doesn’t reduce surface energy)? Reduce cleaning frequency? Rinse with a benign fluid after cleaning to displace the aggressive agent? Avoid wiping high-stress regions?

Training: service personnel may not understand EMFC risks. Simply educating them—“don’t wipe this area with that solvent”—can prevent failures. Make it part of maintenance training.

Inspection: for critical components, implement inspection for stress whitening or surface crazing. These are early warnings. If you see whitening, investigate before cracks develop.

Part Seven: The Deeper Physics—What Else Is Happening

We’ve focused on surface energy, but there are other effects worth mentioning. EMFC is complex, and surface energy reduction, while the primary mechanism, isn’t the only thing going on.

Effects on Craze Fibrils

Crazes contain polymer fibrils—incredibly fine threads, five to thirty nanometers in diameter, stretched several times their original length, bridging across voids. When fluid replaces air in a craze, it affects the fibrils directly.

Reduced fibril formation energy: creating new fibrils requires generating new fibril surface area. Lower surface energy makes this easier, requiring less stress to form new fibrils during craze widening.

Fibril instability: fibrils are thin cylinders under enormous tensile stress. They’re stable against breakup partly because surface energy resists the increased surface area that would result from fibril breakup. Reduced surface energy reduces this stabilization, making fibrils more prone to necking instabilities and breakup.

Chemical attack: in aggressive fluids—especially those that can cause chain scission—fibrils are particularly vulnerable. They’re highly stressed (stressed bonds break easier), have high surface area (more fluid contact), and contain oriented chains (less entanglement, easier to pull apart). Fluid can attack fibrils directly, causing premature fibril failure.

When enough fibrils fail, the craze transforms into a crack—true empty space. That’s when rapid fracture follows. Surface energy reduction accelerates this craze-to-crack transition through all these pathways.

Molecular Mobility Effects

Fluids that plasticize polymers increase molecular mobility. Higher mobility has multiple effects.

Easier craze formation: mobile chains can rearrange more easily, reducing the stress required to initiate crazes and draw chains into fibrils. Easier shear yielding: more mobility facilitates shear yielding, potentially suppressing crazing in favor of ductile deformation—this is protective, since shear yielding distributes damage and prevents crack localization. Faster stress relaxation: the big protective effect—mobile chains relax stress faster, reducing crack driving force.

The net effect depends on whether damage mechanisms (easier crazing) or protective mechanisms (faster relaxation, possible shear yielding) dominate. This varies with stress level, temperature, exposure time, and material properties.

The Concentration Evolution Effect

When fluid penetrates a crack, its local composition may change over time.

Surfactant adsorption: if the fluid contains surfactants, they may preferentially adsorb to polymer surfaces, depleting the bulk fluid concentration. As concentration drops, surface energy reduction effectiveness may decrease. Selective evaporation: for multi-component fluids (like detergent solutions or solvent mixtures), different components evaporate at different rates. The composition shifts, potentially becoming more or less aggressive. Dilution: water absorption from humidity can dilute organic solvents in cracks, reducing effectiveness. Contamination: polymer degradation products, leached additives, or environmental contaminants can accumulate, changing fluid chemistry.

These effects can reduce EMFC aggressiveness over time in a single continuous exposure—the fluid becomes “spent.” But cyclic exposure with fresh fluid replenishes active components, maintaining high aggressiveness.

Your analogy to crevice corrosion is perfect here. In crevice corrosion, oxygen depletes, pH shifts, and the process becomes self-limiting until fresh electrolyte flushes the crevice. In EMFC, similar self-limiting effects occur, but are defeated by repeated fresh fluid application.

Part Eight: Some Final Thoughts on Thermodynamics and Failure

Let me wrap up with some broader philosophical points about what energy-mediated fluid cracking teaches us.

Thermodynamics Ultimately Governs

Fracture—crack growth, crack formation—is fundamentally a thermodynamic process. It happens when it’s energetically favorable, when the energy released exceeds the energy required.

Griffith understood this a century ago. His energy balance approach transformed fracture mechanics from empirical stress calculations to fundamental thermodynamics.

Energy-mediated fluid cracking is a beautiful illustration of this thermodynamic control. Fluids don’t mechanically weaken polymers. They don’t add stress. They don’t physically push cracks apart. They simply change the accounting—reduce the energy cost per unit crack extension. And that changes everything.

A crack that was thermodynamically stable in air becomes thermodynamically unstable in fluid. Energy balance tips toward crack growth. Failure becomes favorable. And thermodynamics is patient but inexorable—if failure is favorable, it will eventually happen.

Scale Connections Matter

Understanding EMFC requires connecting multiple scales. Molecular: interactions between fluid molecules and polymer chains determine adhesion, work of adhesion, interfacial energy. Nanoscale: craze fibrils are nanometer-scale structures; their formation, stability, and breakdown involve nanoscale processes. Microscale: crazes are microscale features; fluid penetration, void formation, crack tip advance all occur at micrometer scales. Macroscale: component failure is macroscopic—a crack grows to millimeter or centimeter scale, causing structural failure.

You can’t understand the macroscopic failure without understanding what’s happening at every scale below. The molecular interactions determine surface energy. Surface energy governs crack growth at microscale. Microscale crack growth accumulates to macroscopic failure. This is systems thinking. This is holistic engineering. Every scale matters. Every mechanism connects. Understanding one scale in isolation is insufficient—you need to see the whole chain of causation.

Materials Communicate

I always say materials tell their stories. EMFC is a perfect example.

Stress whitening from crazing is the material showing you internal damage. Distributed whitening says “I’m being attacked uniformly.” Localized whitening says “stress is concentrated here.” Progressive whitening over time says “damage is accumulating.” Surface crazing says “stress, check; aggressive fluid, check; EMFC is happening.” Through-cracks say “I reached critical size; energy balance tipped past stability.”

These aren’t just failure modes to document and dismiss. They’re evidence. They’re communication from the material about what happened, what conditions existed, what mechanisms operated. Read the evidence carefully. See what the material is showing you. Let it teach you what went wrong and what to do differently.

The Value of Field Observations

Textbook knowledge is essential—the theory, the frameworks, the fundamental mechanisms. But field observations reveal complexities theory alone might miss.

The wet storage paradox. The swab test versus immersion difference. The cyclic exposure aggressiveness. These came from careful field work, troubleshooting real failures, paying attention to what actually happens rather than what should happen according to simple models.

Don’t discount field observations because they seem to contradict theory. Instead, use them to refine understanding. Ask “why does this happen?” Use theory to explain observations, and use observations to guide theory development. That back-and-forth between theory and practice, between fundamental understanding and real-world complexity—that’s where deep knowledge comes from.

Conclusion: The Story Surface Energy Tells

We’ve covered a lot of ground. From Griffith’s energy balance to surface thermodynamics, from capillary action to stress relaxation, from swab tests to wet storage paradoxes.

Let me distill it to the essentials.

•     Energy-mediated fluid cracking happens because fluids reduce surface energy. Reduced surface energy means reduced crack resistance. Cracks that were stable become unstable. Cracks that were growing slowly grow rapidly.

•     Which fluids are aggressive depends on molecular interactions. Fluids molecularly similar to the polymer reduce surface energy dramatically. “Like dissolves like” explains specificity. Surfactants are particularly effective because they’re optimized to reduce surface tension and wet surfaces.

•     Surface energy reduction demands more crack surface area. When surface energy drops, the existing crack isn’t in energy balance anymore. It must grow—both deeper and longer—to restore equilibrium. Your insight about depth and length is exactly right—it follows directly from thermodynamic balance.

•     Cyclic exposure can be more damaging than continuous exposure. Continuous exposure allows protective mechanisms (stress relaxation, equilibration) to engage. Cyclic exposure with fresh fluid prevents equilibration, causing cumulative damage with each cycle. The wet storage paradox illustrates this beautifully.

•     Localized application can be more aggressive than immersion. Swab tests deliver concentrated fluid to high-stress locations without time for protective mechanisms. Immersion creates uniform exposure with time for global stress relaxation. Different outcomes from the same fluid.

•     Time scales determine outcomes. Fast processes (surface energy reduction, initial crack growth) compete with slower processes (stress relaxation, equilibration). Exposure duration, temperature, and cycling determine which processes dominate and thus whether damage is catastrophic or manageable.

•     Testing must match service conditions. Standard immersion tests may not predict cyclic exposure behavior. Localized application tests may reveal vulnerabilities immersion misses. Test as parts will actually be used.

•     Design has multiple strategies. Reduce stress. Prevent fluid contact. Choose materials with good stress relaxation. Minimize residual stress. Design for drainage. Seal critical regions. Rethink assembly to eliminate sustained stress.

•     Materials tell stories. Stress whitening, crazing patterns, crack locations—all are evidence of conditions and mechanisms. Read the evidence carefully. Let the material teach you what happened.

That’s the surface energy story. That’s how fluids kill polymers. That’s energy-mediated fluid cracking understood through thermodynamics and kinetics, enriched by field observations and practical wisdom.

Understanding EMFC deeply—not just “fluids cause cracks” but why and how and under what conditions—enables intelligent material selection, effective design, meaningful testing, and successful troubleshooting when things go wrong.

Which they will, sometimes. Materials fail. Components crack. Parts break. That’s engineering reality. But with understanding, failures become learning opportunities. Evidence becomes insight. And insight enables prevention.

That’s the journey from failure to wisdom. That’s the path from broken parts to better designs. That’s engineering—understanding deeply, designing thoughtfully, learning continuously.

Thanks for joining me on this deep dive into surface energy, thermodynamics, and the surprising complexity of how fluids affect crack growth. I hope you see energy-mediated fluid cracking differently now—not as mysterious material weakness, but as predictable consequence of energy balances, explainable through physics, preventable through understanding.

Now go look at your components, think about their stress states, consider their fluid exposures, and design with this knowledge. Make things that last. Make things that resist failure even in hostile environments. Make things that work.

That’s the goal. That’s the craft. That’s engineering done right.

And when failures happen—because they will—read what the material is telling you, understand the mechanisms, fix the root cause, and build better next time. That’s the cycle of improvement. That’s how we learn. That’s how engineering progresses.

Listen to the materials. Understand the thermodynamics. Design with wisdom. That’s the holistic way.

Thank you for listening.

This has been Joe McFadden.

Combating engineering mind blindness.

Engineer. Lifelong Learner. Holistic Analyst.

www.McFaddenCAE.com  ·  mcfadden@snet.net

Have a thoughtful and wonderful day.