Friday, July 12, 2019

Painting Mistake and Wrapping Up the Body | Roundtail Restoration

Holy cow! I just looked and it's been almost a month since my last blog update. Whoops! I did have some vacation in there, so there was that, but I'll try to get caught up here somewhat.

First, the new compressor works fine, but I don't know how to clean a paint gun! To the video:


I was able to get back over to the garage within a day of the compressor failing so that I could spray the epoxy that I had mixed up when the compressor failed. The pot life on the epoxy primer is north of 72 hours (temperature dependent) and I was at about 36 hours since mixing, so well within the window.

Given that, I gave it a quick stir, set everything up and laid the paint down. This is what I ended up with:

Looks like my Raptor Liner!

That wasn't good. I recognized it after laying down the first coat and decided to lay down a second coat. The texture wasn't too bad and I figured I could block it out. But why, oh why, did this happen? Turns out my lack of experience, and tendency to plow through, led me to miss obvious signs of a problem.

First, I had to crank open the paint supply valve on the gun much more than I normally do based on my pre-paint testing. I normally do about 1 1/4 turns open on the supply for my first epoxy coat. I needed over 2 turns this time. That was my first indictaion.

Second, the spray pattern itself was kidney-bean shaped. This shape is indicative of either a clogged fluid tip or air cap. I knew something was up, but wasn't sure what. But, again, I plowed through, resulting in two wet coats of textured epoxy. While the look was cool, it wasn't what I wanted, of course!

The spray pattern.

After I put down those two coats, knowing I had a problem but not why (yet), I called it a night before I did any further damage.

I returned to the garage, having figured it all out after asking around on the SPI forum and got to blocking. Fortunately, though it took a lot of elbow grease, I was able to block all of the texture out.


The dark areas are where I haven't blocked down to, yet.

The passenger's rear wing, post-blocking.

I guess one good thing about this, in hindsight, is that I got another good blocking session out of it. I started with 220-grit because I didn't want to burn through if I could help it. While this took more time to get the texture out, it did provide another chance to get everything flat again. Got to always look for the positive in learning something!

With that mistake taken care off, it was onward and upward, with build primer next. I did about 3 full coats of build primer, waiting 5-minutes in between coats to let it flash.

Build primer done!

That was all I had time for that visit and I returned the next to start blocking. I remember to use some guide coat this time and started blocking it at 220-grit. It went fine with some burn-through areas to bare metal, but I expected that. 

Passenger's side, post-blocking.

After that, I broke out my 3M random orbital sander and sanded it all with 320-grit. This was very nice and a hell of a lot easier than blocking by hand. From my research and a bit of common sense, once you start getting above the 200's for sandpaper grit, you'd really have to stay in one area for a while before you start to make a sizeable dent in the paint.

I'll hand block out to 220-grit, but above that, even with not much experience, I consider myself safe to use an random orbital sander from that point out. One other nice thing about random orbital stuff is that, unlike direct-drive sanders (a gross example be an angle grinder), the random orbitals will stop spinning if you apply too much pressure. That makes it a bit forgiving.

Don't get me wrong, you can still mess up your paint and cause some waves, but it's a bit harder to do with a random orbital. The same goes for polishers, but I won't need to worry about that until after clear coat!

Speaking of clear coat, I tried to simulate it by spraying down the driver's side rear wing to get a look at how bad it was, waviness-wise. I was pleasantly surprised. Not too bad. But, I was ready to be done with that stuff, so that's all for now. Cheers!

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