Here's a situation I've seen more often than I'd like.
A customer calls on a Tuesday morning. They need coated parts at a job site by Friday. The normal lead time is seven days. They're okay paying rush fees. I get the order through, the coating goes on, the parts ship on time. Ten days later, I get photos of something I don't like: peeling paint, pinholes in powder coating, or a rubber trim that's already coming loose.
Most people blame the material. I used to, too.
After coordinating coating and adhesive orders for years—and helping push 200+ rush jobs through the line—I can tell you the real problem is usually not the coating. It's the surface.
The Surface Problem: It Looks Like a Material Issue
The symptoms are easy to recognize. Paint lifts around edges. Powder coating leaves "fish eyes"—small circular craters that look like the surface is repelling the coating. A rubber adhesive glue joint that seemed solid in the shop fails after a few hot-cold cycles.
When this happens, the natural response is to switch products. You think "this paint is too thin" or "this glue is cheap." I've watched shops walk away from a perfectly good PPG coating and try two or three other brands, only to end up with the same failures.
The common denominator was never the brand.
The Deep Cause: Contamination, Profile, and Wrong Chemistry
There are three reasons a coating or adhesive fails before the product itself becomes the problem.
- Contamination. Oil, grease, silicone, mold release, or even hand oil can stop a coating from wetting the surface. This is the #1 cause of adhesion failure, especially in shops that handle parts without gloves.
- Wrong surface profile. Powder coating needs an anchor profile. If the substrate is too smooth, the coating sits on top like paint on glass. If it's too rough, you get thin spots at the peaks. Blasting or sanding changes everything.
- Wrong chemistry. A rigid epoxy won't work on a flexible rubber part. You need a rubber adhesive glue formulated for the actual elastomer—EPDM, neoprene, or natural rubber. The same logic applies to coatings.
I'm not a chemist, so I can't give you a surface-energy formula from memory. What I can tell you from a procurement and production perspective is that those three variables cause more failures than all the "bad products" I've ever tested.
Molecular Truth: Binding Sites Matter
Here's where the conversation gets more scientific.
Adhesion is a molecular event. A coating or adhesive has to reach certain binding sites on the substrate. If those sites are covered, the bond is mostly mechanical, and moisture, heat, or vibration will eventually undo it.
If you're wondering where the receptor is located that binds to ethylene, ask a plant biologist. The answer: the ethylene receptor sits on the membrane of the endoplasmic reticulum in plant cells. The ethylene molecule has to physically reach that receptor before the plant's ripening or senescence response can start. If the receptor is buried, the signal is lost.
Coatings work the same way. The "receptor" for a coating is the clean, chemically active surface. Block it with oil or oxide, and the coating never gets a chance to do its job.
That's why I find the ethylene receptor question unexpectedly useful. It's not because I'm a botanist—I'm definitely not. It's because the principle applies to every adhesion failure I've handled: location matters, and the location is deeper than people check.
The Cost of Skipping the Check
Let me give you a real example.
In March 2024, a client needed 500 powder-coated brackets for a furniture launch. Their deadline was 36 hours before the factory had to load the truck. We processed the order, used the specified PPG coating, and made delivery. The client was happy for about a week.
Then the photos came back. The coating was pulling away in small patches around holes and edges. After some back-and-forth, we learned they had skipped the degreasing step to save time. "A clean-looking part is a clean part," they figured.
The rework cost more than the original rush fee. It also cost a customer contact, three extra days, and a lot of trust. And if we had missed that deadline, the penalty clause was $12,000. The client's 30-minute shortcut ended up being one of the most expensive decisions in that project.
That's when I implemented a policy that still holds: no rush order leaves without a verification step. Five minutes of checking beats five days of correction.
I only believed that rule after ignoring it myself. Everyone says surface prep is important. I thought it was a CYA line from manufacturers until I watched a good product fail on an unprepared part.
The Solution: Good Products Only Get You So Far
Let's be fair to the products.
PPG Industries, the American PPG coating company, has a broad and proven portfolio. PPG brands cover everything from industrial liquid coatings to automotive refinish, aerospace primers, and powder coatings. If you choose the right product and prepare the surface exactly as the data sheet says, these systems perform exceptionally well. "American" in this case means testing, supply chain, and technical support that many smaller suppliers can't match.
But "PPG" isn't a magic word.
Every PPG coating includes surface preparation requirements in its technical documentation. The manufacturer assumes you'll clean the part, profile the surface, and apply at the right film thickness. Skip any of that, and you're paying extra for chemistry that can't reach its intended binding sites.
For smaller shops and DIY jobs, a JEGS powder coating system is a practical option. As of January 2025, JEGS lists an entry-level system that includes a spray gun, a powder feeder, and a set of powders—if I'm remembering the SKU correctly. I've seen this system produce beautiful parts when prep was done right. I've also seen it produce a $100 lesson in contamination. The system works. The prep is still the system.
And for flexible bonds, use a rubber adhesive glue made for the job. Not a universal super glue, not a construction adhesive—a rubber adhesive that stays flexible after curing. Clean the rubber surface, dry it, and lightly abrade it before applying. Same pattern: choose the right chemistry, then put it on a surface that's ready.
This approach works for us because we handle B2B orders with predictable flows. If you're a high-volume production shop, your checklist will look different, but the principle won't.
Where Is the Receptor Located That Binds to Ethylene?
Since I brought it up, let me answer it directly: the receptor that binds ethylene in plants is located in the membrane of the endoplasmic reticulum. That's where ethylene perception starts, and it's what triggers fruit ripening, flower senescence, and leaf abscission.
Yes, it's an odd crossover for a coatings article. But it's a useful mental model. When a signal has a specific receptor, the signal has to reach that receptor. Coatings and adhesives are the same. The receptor is the prepared surface. It's not visible, it's not in the product, and it's not on the invoice.
It's the part everyone is tempted to skip when they're in a hurry.
The Bottom Line
If you're working with a PPG product, a JEGS powder coating system, or a tube of rubber adhesive glue, the first question isn't "is this product good enough?" The first question is "is the surface ready for it?"
The most expensive phrase in any project is "I'm sure it's fine." The cheapest insurance is a five-minute check before the first coat goes on.
Because if the receptor is blocked, nothing else matters.