Not Aero specific, but I did have to do this on my Aero.

Does anyone on this forum paint their own cars? I'm trying to figure out how to blend in a spot repair. I've read books on this, and I've gotten everything down, except for the last step of blending in the top coat with the old paint. It seems that what's actually happening is quite different from all the written descriptions in the books; the oversprays just mess up the surrounding areas.

What's the best trick to minimize oversprays? I've tried different gun angles, pulling the gun away and lightening the trigger at the edges, and different reductions and air pressures. There are so many different variables, and I seem to keep missing the right combination. I keep ending up with rough transitions. This is polyurethane clear with a gravity fed HVLP gun.

Any advice would be appreciated

 

best to paint whole panel or to a break line with masking protection...
you won't find many professional shops messing with spot spray blending
difficult enough getting a color shade match let alone getting smooth bonding on blend overspray

the new poly clear coat is probably chemically reacting with the old clear coat or top coat of paint

 

Well, it's not always possible to do the whole panel. In this case, the spot is at the rear pillar near the roof, and there are no convenient break lines. The "whole panel" would be the roof, the front pillars, and the rear quarter panels. Essentially the whole car, minus the doors, front fenders, and hood.

I guess I'll have to go back out and practice.

I think the previous surface has a catalyzed polyurethane clear coat, so the new paint should not be reacting with it. However, I found that if you don't use enough activator in the new paint, recoating will cause it to craze.

 

contact your local junior college auto body shop class department....you could set in on their sessions covering spot repairs and painting

 

I've been trying my hand at painting and have come up against the same issue as you are having. I posted a query in the 'Paint/Bodywork" section about this and received some advice about using a reverse masking technique to better blend the spot repair. You can do a search on that forum under "Blending Spot Repair" and it should come up. After reading their answers, I was still uncertain how a reverse mask works and have not tried it as yet.

The best method I've found so far for small spot repairs is to just throw some masking paper on at the major demarcation points, (door/fender/hood seams) shoot the repair area and feather the paint out onto the surrounding solid paint. Let it all dry well then go back with a buffer and rubbing compound to cut down the feathered, overspray, working also across the newly repaired spot. I do this several times with different compound grits until I am satisfied with the blended result. Finish with a polishing compound and a clear coat if it is a two part paint.

I've tried using my old tried and true pressure feed gun, a new HVLP gun, a small spot gun for spot repairs. I know this is heresay, but lately, I've gone back to using a rattle can approach for small ding and nick repairs. The local paint store can put up a one part, custom-mix acrylic enamel in a 16oz aerosol can. The color match is superior to anything commerically available such as Dupli-Color, etc. It lays down well, covers with just a few passes and leaves less overspray than the guns. Plus, the cost is way less than having to buy a quart of regular paint. A 16oz can is only $25.00 vs a quart of the same paint for around $85.00. The downside is the prolonged drying time required. It takes around two weeks to fully dry before you can use compound on it.

 

I am still working with the clearcoat. I set my gun to the lightest fluid delivery rate that didn't spray powder, which required very slow strokes to get adequate coverage, but leaves very light layers, so the edges really were feathery. Unfortunately, this new clearcoat looks so deep compared to the old stuff, that even if I managed to buff out the overspray, it won't really match. So I ended up coating the whole roof and front pillars, and followed the rear pillars to a horizontal crease in the body.

The good news is, the surfaces looked like glass right after I finished spraying. The bad news is, after giving it a few hours to cure, I came back to find that lots of dust particles, and a couple of insects, have fallen into the coating before it flashed over. And I discovered some sagging on some of the vertical surfaces. (@#$%^&!!!)

So it looks like I will have to do some sanding after the stuff thoroughly dries. Too bad I couldn't have left the as-dried surface; the parts that aren't contaminated still look like glass.

 

you need a pressurized air filtered spray room
it's part of the reason why professional commercial paint jobs cost $1000 +

 

He Hee, misery loves company. Been down that road too. All part of learning and better appreciating the artistry of the guys that do this for a living.

For one of my first projects I painted a horse trailer outdoors . It was looking terrific - glassy smooth, high gloss finish. Then, along came a swarm of gnats.......... wouldn't just die... oh no, they had to swim around awhile before finally becoming permanently bonded to the trailer.

 

Xlt4wd90:

Have you tried mixing in a see through color (My mind went blank and I can't remember what its called) like your van with the clear coat? Or mix some of the clear coating you're using in with the paint you're using then spray it?

JaY

 

im all for the rattle can on very small areas if it is rough but you have enough pain on it you can always wet sand and buff as for needing the special paint room you dont ned it my buddy has ran his body shop for 20 plus years with out one he turns out better paint jobs than the dealers do around here as a matter of a fact hes got a porche in that a dealer just painted the hood and sides from the moldings down on it looks like hell from 10 feet it is fine but up close it is awful dirt in the pain it feels rough when you run your hand over it there break line is very obvious the guy took it from the dealer to his shop and said to do it right wich he will with no special paint room

 

In fact, one of the spots I'll have to go over is also from a moth that died slowly. It fluttered around a 4" square area, leaving parts of its body along its squiggly trail, embedded in the coating. From now on, I'm going to do large areas early in the mornings, when most insects are either dormant or dead already.

Jay, I did not ever try to mix the clear with the color coat. The color being a metallic paint, its appearance would be quite different from what was intended.

I've done spot repairs with paint from spray cans. And yes, they are usually mixed perfectly for convenient application, if you hold the position just right and compensate for different temperatures. But one problem I've encountered is that they don't really cure to as durable a finish as the two-part systems. So one time I accidentally oversprayed some Gumout on a part that I had finished with color from a can and then topped with clear from a can, and the paint got eaten away, right down to the catalyzed primer. The primer was fine, but I had to redo all the paint above it.