Rattle Can Problems

[KVH]

I really did a great job filling, sanding and preparing my car door for paint and clear coat. I read every youtube and article I could find. I talked to my local auto shop and paint shop. This wasn't my first attempt. I'd done an "OK" job before. But this is the worst product I've created in recent memory. Maybe too much paint. But I just can't explain it. I was so careful. I put the clear coat on, thin, then heavy and slow. Granted, it seemed to take too many paint coats to cover the primer, and too many clear coat passes to "look" even, but, otherwise, I really felt I followed the book. The result is a mess. Rough, thick, bumpy and irregular. Any kid messing around with his dad's tools and paint could do a better job.

I took my finished product down to my favorite paint and body shop. My buddy laughed and said that if I wanted to keep playing around with inconsistent results I could use rattle cans, and try color sanding and buffing my clear coat, but that if I wanted to graduate to a level where these kinds of errors are avoided, I need to get a paint gun and learn the correct application methods using good equipment, a compressor, and maybe even a makeshift booth of sorts.

I've seen some great work with rattle cans. I even created one or two that "pass." But this latest experience leaves me baffled. A few too many paint coats? Maybe poor lighting threw me off on the number of coats needed. Maybe a bit too warm (82 degrees). I'm left with impression that there are too many factors to throw a person off using rattle cans; they're more temperamental, less forgiving. I don't know.

What I do know is that I could benefit from hearing the experiences of others, and that's the reason for my post. Any thoughts or advice would be much appreciated. KVH

 

[Bayless]

Probably not what you want to hear but I agree with your "body shop buddy."

 

[KVH]

Should I have sanded after the basecoat and before the clearcoat? Why would I have done that, when the Spray Max instructions state no such procedure? Should I try to bring down the roughness and and smooth out the clearcoat with 800 or 1000 grit as it now exists, or would I just be wasting my time?

 

[JHaydon]

Very limited experience here, but I have participated in a couple of "proper" paint jobs (mostly standing by watching and making sure the air hose didn't hit the fresh paint) and I've rattled more than my share of spray cans over the years.

I think the biggest drawback to rattle cans -- and the main reason that experienced painters don't like them -- is that they don't allow the user to control the process. With a paint gun, you control the thickness of the paint, the air pressure, the nozzle setting; squeezing the trigger a different amount has a certain effect, etc. With a can, it's all pre-mixed with a fixed nozzle and a preset pressure, and just about all you can do is either press the nozzle or not.

Sort of like automatic vs manual transmissions. Either one can get you around a corner, but one requires a certain set of skills to do it right and the other requires a certain creativity to work around the built-in compromises. In the end, you may not get the same results (just like you'll never turn the same lap times on a road course with an auto trans), but it can be much more satisfying when you get an above-average finish the hard way. I have seen some very experienced painters use rattle cans with some amazing results (sorry, I don't really know the tricks).

If the color coat is rough, sanding the clearcoat probably won't make it look great. In fact, I think that if the base is really uneven or lumpy or orange peeled, you may sand all the way through the clear without seeing the results you want. I'm picturing those weathered barn-wood tables that have a 6mm layer of clear epoxy on them -- smooth surface, but you can clearly see the roughness underneath it.

My prediction is that if you sand all the way back down to the color coat (implying that you not only remove all the clear but also flatten out the color coat) and then re-spray the clear you'll be much happier with the results. And then you can take it back to show it off to your body-shop buddy. Yes, it will have taken an insane amount of work but it will be 100% YOUR result.

FWIW, I used brush-on touch-up paint to fill in a chip in the front fender of my Bentley (pure black, no metalflake or pearl). I leveled the edges of the chip with sandpaper, slowly built up the area with paint (I think I used like 12 coats), then wet-sanded with medium, fine, super-fine, and then ultra-fine paper. I didn't even have to use polish, the 30k-grit paper left a mirror finish. I couldn't even show you the repair now because I can't find it.

It can be done!

 

[KVH]

Didn’t the sanding dull out the edges around your scratch. Or are you saying your sanding stayed at the clear coat level? And remained shiny after the 3k grit? BTW my scratches were too deep to “fill” with paint.

 

[JHaydon]

This was actually on an older finish without clear coat, but the process is similar. The chip was all the way down to the primer. And BTW, it was 30,000 grit, not 3000. CRAZY-fine, it felt as smooth as printer paper. I probably would have taken off more paint rubbing with my bare hand.

I got the guts to tackle it after watching a demo on the YouTube channel "ChrisFix". He fixed a deep scratch (down to the primer in some spots) using 2-stage brush-on paint on a clearcoat finish. His technique was to start by sanding down the edges of the scratch to make a smooth transition to the surrounding paint, actually turning the thin scratch into a wide low spot. (Change the cliffs into gradually-sloping beaches.) Then fill in and build up the low area with many many thin coats of paint, then wet-sand it to even out the surface, then clearcoat, then wet-sand until smooth, then polish to make it shiny again. Then wax, wax, wax.

I think his demo job must have taken him a week or maybe a couple of full weekends. My repair was done 3 weeks after I started, just because of long pauses where I was doing actual work. I think I spent a full day layering paint, waiting 10 minutes between coats. Then I had to spend a second day doing it again because I sanded through in a couple of spots.

My big takeaway from that demo, and from other demos of unconventional paint jobs, is that wet-sanding can fix almost anything!