The Answer Isn’t Clear

October 7th, 2016

Paint Delamination is Now as Certain as Death and Taxes

You won’t believe this. I’m picking one of my old hobbies up again.

That’s so out of character for me.

A very long time ago, I decided to put new side covers on my Moto Guzzi. The model I bought came with terrible, cheap side covers that crack and fall off. The problem is so bad, some guy on the Internet makes money selling covers he makes from thick fiberglass. I bought two.

Problem: the covers weren’t painted. So I found a source of base coat/clear coat products, and I bought paint. Then I procrastinated for practically ever. Then I went back to the project, bought the correct primer, and primed and sanded the covers. I didn’t quite finish. I sanded through the primer in a couple of places on one cover.

That’s where I stopped. Since then, the project has been in the gravity well of the black hole where my hobbies vanish.

I was intimidated by the prep work. I hate painting to begin with, because it’s very hard to do correctly. I hated priming and sanding the covers, because it was a big, tedious job. I thought I would have to repeat it with the paint and clear coat.

Sadly, I was laboring under a delusion.

My motorcycle painting knowledge came from a set of DVD’s made by a motorcycle painter named Fritz. The DVD’s are really good, but they weren’t completely applicable to my project. I didn’t know that.

Fritz didn’t use clear coat. He sprayed his stuff with primer, sanded it, sprayed it with some color or other, sanded it, applied graphics, sprayed it with another color, sanded it…he did a lot of sanding. I figured I would have to do that with my base coat and clear coat, and that would be a lot of work. Also, I would be pretty likely to have to do a lot of it over, because I would surely sand through something.

I was thinking about it today. I realized the DVD’s didn’t depict the kind of work I was going to do. I decided to check something out. I Googled to see if it was necessary to sand the base coat in a base coat/clear coat application. Guess what? It’s not.

Car makers like base coat/clear coat (“BC/CC” or “2-stage”) paint, because it’s cheap and requires little skill compared to real paint. The primer has to be done well, and the clear coat has to be done well. The base coat is just slopped on. You don’t have to sand it, because (apparently) the clear coat covers the crappiness of the base coat surface. And supposedly, clear coat is thick, so you stand a pretty good chance of sanding and buffing it to perfection without blowing through it.

Personally, I do not like clear coat. It always, always goes bad sooner or later, even if you wax it, unless you never park in the sun. When it goes bad and peels, it can’t be fixed. You have to sand it off and replace it, and that means redoing the base coat as well. You can’t dissolve it, so it’s impossible to paint more clear coat over it, expecting the new clear coat to bond with the old. It will just sit on top, so in order to fix a small peeled area, you may have to repaint an entire hood or door.

That’s just stupid.

Old-style paint is different. If you screw up an area, you can sand it back and paint over it. If you have to completely redo it, you don’t have to fool with a clear coat. You just scuff it up and paint again. That’s my understanding, anyway.

Remember how long the paint lasted on your 1970 Buick? Remember how it didn’t peel after twenty-five years? Remember how it came back to life when you buffed it? Modern paint doesn’t work like that. It is 100% doomed to failure unless you park indoors. When it fails, you have to replace two finishes, not one, and you have to do entire panels, which generally means the whole car.

Many people think wax prevents clear coat peeling. That appears to be incorrect. People think clear coat peels because chemicals get to the clear coat. In reality, clear coat peels because it expands and contracts at a different rate from paint. Every time your car heats up, the clear coat and paint expand to different degrees. That puts tension between them; they pull sideways on each other. That loosens the clear coat. Then it comes off.

Wax won’t prevent that. Maybe it will block UV radiation, but it won’t turn clear coat into a material that expands and contracts with paint. Clear coat is plastic, like a billiard ball. Nothing dissolves in it. You can’t add a conditioner that makes it more elastic. It is what it is what it is, forever.

You can go to a junkyard in South Florida or Arizona right now and find a 1960 car with the paint intact, and you can wash, buff, and wax it back to a nice appearance. Try that with a 1990 car. I don’t think you will have much luck.

The two areas where two-stage paint seems to excel are shine and ease of repairing shallow scratches.

I may be totally wrong about this, but I don’t think I am. It’s very hard to get information. Car painters love 2-stage paint, because it’s easy to apply, and probably because they know it will fail and bring them more business. Manufacturers praise it because they sell it. Detailers and wax manufacturers love it because it gives them something fragile for their products to protect. On top of that, most people who talk about the subject are ignorant blowhards who repeat everything they hear without checking. If some uneducated doofus on a car website says wax protects clear coat, 95% of ignorant blowhards will repeat it and get angry if you disagree.

By the way, care to guess one of the big hidden reasons we use 2-stage paint now? If you guessed “EPA,” get yourself a cigar. Somehow or other, 2-stage paint is greener. It’s no surprise if it’s also inferior. How often do green alternatives work as well as the technology they replace? About as often as Mexicans buy Trump shirts.

Tonight I mixed a tiny amount of primer and touched up the bare areas on the side cover with a Q-Tip. That will make a lot of car nuts groan, because they think you can only apply car paint with a sprayer. That’s not true. It’s fast with a sprayer, but you can brush it if it makes you happy. I’ve already used a brush on the covers, and it worked perfectly. It sure beat mixing up a wasteful, expensive amount of primer to spray and then starting the compressor and air dryer and rigging up the spray gun. Ten minutes of effort as contrasted with two hours.

I’ll sand the cover down, and then maybe tomorrow (or not) I’ll hit it with the base coat and clear coat. I may wait until I come up with graphics; I’m not sure. I have to be ready with graphics when I spray the base coat, because you have to apply the clear coat within 24 hours of spraying the base. I want to have a plan before I go to work.

I look forward to getting these side covers off of my end table. They have been in my way long enough.

If what I’ve written is wrong, let me know, but please don’t be an ignorant blowhard. Don’t say, “Everybody knows…”, or, “I only use 2-stage paint, and here is what I think based on my limited experience.” Let’s have some science and engineering instead of mindless regurgitation.

3 Responses to “The Answer Isn’t Clear”

  1. Stephen McAteer Says:

    My accident-prone brother dented and scraped my newish car a week or so ago. He exposed a tiny bit of bare metal in the process. I got some acrylic spray paint from eBay to cover it over and at least stop it rusting but I think I’ll try your q-tip idea as my experience with aerosols hasn’t been great in the past.

  2. Steve H. Says:

    Taking advice from me on car painting is risky at best.

    You might want to try a paint brush from an art supply store.

  3. Stephen McAteer Says:

    Actually I have a little can of touch-up that has a tiny brush in it. Might try that instead, although the scraped area is quite big.