yet another finishing / sanding dilemma...

[smegolas]

Ive clear coated over metallic green, and 400 grit wet sanded to get rid of the orange peel. Ive got it mainly smooth, but there are still quite a few orange peel “pockets” – the shiny little holes. The problem is Im starting to get some green on the sandpaper in parts – so Im sanding through but still have orange peel, which I don’t really understand. Im scared to sand anymore.

So what do I do now? Re spray with clear and hope it “self levels” somewhat? If so, how many coats? And do I need to polish the sanding scratches out first? If I put, say 20 coats on, will that reduce the risk of sanding through before I can sand out all the orange peel?

Incidentally, what is considered a “coat”? Is it just one pass, or is it 3 or 4 passes?

[RodeoTex]

Yes, putting more cleat coats on is about all you can do.

[Mojotron]

Originally Posted by smegolas

Ive clear coated over metallic green, and 400 grit wet sanded to get rid of the orange peel. Ive got it mainly smooth, but there are still quite a few orange peel “pockets” – the shiny little holes. The problem is Im starting to get some green on the sandpaper in parts – so Im sanding through but still have orange peel, which I don’t really understand. Im scared to sand anymore.

So what do I do now? Re spray with clear and hope it “self levels” somewhat? If so, how many coats? And do I need to polish the sanding scratches out first? If I put, say 20 coats on, will that reduce the risk of sanding through before I can sand out all the orange peel?

Incidentally, what is considered a “coat”? Is it just one pass, or is it 3 or 4 passes?

I consider "one coat" as one "spraying session" - generally that would be 3 passes with lacquer or 2 passes with thicker stuff like poly or shellac. For the sake of being clear - a "pass" is, starting the spray away from the piece being painted, a uniform distribution of spray moving from .75' to 1' per second.

I think the rule of thumb for lacquer is 3 passes per coat, 3 coats per day, 3 days between coats.

If you get into the color coats at all, you want to add clear, and add clear across the whole surface so that the finish is uniform in thickness on the whole piece.

[smegolas]

ok do i have to buff and polish out all of the sanding scratches now before re-clearcoating? otherwise, i will have sanding scratches under the new clearcoat will i not?

and - should i do a whole wack of coats, to be safe?

also - is spraying in cold weather a problem?

[dcxs]

I would agree withRodeo Tex that more coats are needed and with mojotron that 3 complete passes in one session could be considered a coat and that 3 coats would be the minimum I would lay down before trying to sand. Spraying lacquer in cold weather is a problem because you generally have to use more thinner, more coats and, well it just goes on so much smoother in warm weather. You seldom have to worry about orange peel. The real issue though is relative humidity and something called the dew point which you can calculate or look up for you local. I think it is the temperature at which water condenses at sea level. A rule of thumb is that you should have an ambient temperature that is 25 degrees above the dew point to avoid fish eye cloudiness (or water condensing in your finish). Other than that, you can spray in cold weather but your battling orange peel and must spray more coats and a lot more sanding.
Hope that helps.

[Mojotron]

Originally Posted by smegolas

ok do i have to buff and polish out all of the sanding scratches now before re-clearcoating? otherwise, i will have sanding scratches under the new clearcoat will i not?

and - should i do a whole wack of coats, to be safe?

also - is spraying in cold weather a problem?

The cool thing about lacquer is that it melts into the coat below quite a bit - so a lot of the sanding marks will get smoothed out. With really consistent spraying the amount of sanding is not that much.

Before doing anymore sanding, I would put on 3 more coats if possible; the last thing you want to do is to sand into - or worse, through - the color coat. A lot of my stuff can end up with 10 - 15 coats of clear.

I've gotten the cloudiness before and it will clear up over time, but you I don't think you can really buff it all out if it's still venting gasses/H2O.

All of this said, I've painted a few guitars, but there are others that are likely much better at addressing finish issues over on the finishing forum.

[Jack Wells]

You didn't say whether you're spraying with a gun or with aerosol cans. If you Google "orange peel paint causes', you'll get several causes and solutions although they apply mainly to spraying with a gun.

If you're spraying with a can, your problem is probably caused by not spraying wet coats. However, you can't spray wet coats in the beginning. You need to first build up a layer of several light coats. Then you can move in closer and spray wet coats that will level out before they stiffen up.

[smegolas]

im spraying with aerosol. so even though ive already sprayed clear you figure i should start spraying light coats and then really load it up with the later coats?