Wet Sanding Metallic Lacquer?

[Tom L.]

Well, the paint is finally down. We ended up with twelve coats of PPG lacquer. The last several coats were very thin, so it flowed out nicely and, mostly, dried with a wet look. I'm contemplating whether to block it out before buffing. Although nearly all of the paint is smooth and wet looking enough that I could buff it without any sanding, there are a few spots that look a bit dry.

I've read in the archives some warnings about wet sanding metallic paint. The car is Laguna Gray, a metallic color. Any thoughts on whether I can safely wet sand?

[Gene M.]

Re: Wet Sanding Metallic Lacquer?

Tom,
If you want the paint flat and straight then wet sand it. If that is not your preference than just rub it out.

If it were mine I would wet sand then rub. But you can't get carried away or the pencil will deduct points on the score sheet.

[Pat M.]

Re: Wet Sanding Metallic Lacquer?

I can tell you that the previous owner of my 70 wet sanded the Marlboro Maroon metallic and he "burned through" the top layer in several spots, resulting in "holes" where the layer in the hole did not match the surrounding area.

It also removed all the orange peel, which is bad for judging purposes.

To avoid this when I repainted the car my painter only buffed it - and it came out nice, correct, and with no burn throughs.

[Chuck S.]

Re: Wet Sanding Metallic Lacquer?

...I'm contemplating whether to block it out before buffing...

The time to have "blocked it" was BEFORE the finish coats were applied.

The objective of block sanding is to level the highs and lows to eliminate imperfections...it's done after multiple coats of heavy primer surfacer and before the final finish coats.

You can wet sand the finish using a "soft" block (heavy durometer sponge) and very fine paper (1000-2000 grit), but this only to remove orange peel before buffing. The purpose of the soft block is only to prevent grooving the finish with finger pressure on the sandpaper. You can't remove enough material from finish coats to really do much smoothing without damage.

Buffing without sanding will provide the most original appearance. You went with acrylic lacquer to make it original, albeit a few more coats than the General...why compromise your objective further at this point?

[Alan S.]

Re: Wet Sanding Metallic Lacquer?

Hi Tom,
The fellow who sprayed the lacquer on my 71 doesn't wet sand the final coat on metallic colors for the reason Pat mentioned. Sanding through to the previous coat seems almost inevitable if the coats are very thin as you describe.
I didn't sand or rub my 71 MM red for many months and then found it took very little rubbing to bring up as high a shine as I wanted because the lacquer continues to dry and harden as time goes by. Do you have time to wait before you do anything?
Regards,
Alan

PS: I'm curious, how much un-thinned lacquer did you use to make up the twelve coats? I have many less coats on my car and used about 7 quarts.

[Bill M.]

Re: Wet Sanding Metallic Lacquer?

Well, the paint is finally down. We ended up with twelve coats of PPG lacquer. The last several coats were very thin, so it flowed out nicely and, mostly, dried with a wet look. I'm contemplating whether to block it out before buffing. Although nearly all of the paint is smooth and wet looking enough that I could buff it without any sanding, there are a few spots that look a bit dry.

I've read in the archives some warnings about wet sanding metallic paint. The car is Laguna Gray, a metallic color. Any thoughts on whether I can safely wet sand?

You shouldn't have to sand the "dry" spots. Just buff it. (You sand the paint to eliminate orange peel.)

If you sand metallic, you may get mottling. I sanded my Milano Maroon very carefully and got just a hint of mottling in a couple spots.

Good luck.

[Tom L.]

Re: Wet Sanding Metallic Lacquer?

Thanks guys. I'm glad I asked.

Alan, I used precisely 7 quarts. I learned from shooting seven or eight test panels to get the color right that the metallic flake looked blotchy if it was sprayed at the suggested mixture of 1:1.5 and at what I would consider a normal rate of coverage. We ended up going 1:2 and spraying very thin coats. By coat three we had the same amount of coverage that I would have expected to see by coat one. It was a slow process, but it worked. The color and metallic flake is completely consistent throughout and has some depth to it. If we didn't have that metallic flake issue, we could have put the same amount of paint down in far fewer coats.

[Alan S.]

Re: Wet Sanding Metallic Lacquer?

Hi Tom,
That's interesting that you used a similar amount of paint.
The fellow who sprayed my car was adamant that the number of coats wasn't an issue, the thickness of the total layer of paint is what's so imortant with lacquer. I believe this is a good case for 'more' not being better.
I hope I get to see your car!
Regards,
Alan

[Tom L.]

Re: Wet Sanding Metallic Lacquer?

Once it's finished, I'm sure I'll see you at a Mason-Dixon meet somewhere with it. I had hoped that would be this summer, but that seems to be a bit optimistic now. The car is still needs all of its wiring, a complete interior, and exterior assembly. I'll be happy if I can drive it around the block once before I put it away for this upcoming winter. The upside is that I have plenty of time to let it sit before rubbing it out.

[Alan S.]

Re: Wet Sanding Metallic Lacquer?

Hi Tom,
I'm patient.... and I'll bet it will be worth the wait to see your work!
Regards,
Alan

[Jim R.]

Re: Wet Sanding Metallic Lacquer?

Since you used lacquer i'm assuming you are getting your car judged, so to get you the most points you should only do as the factory did, buff from the center body line up.