Dulling Down a Lacquer Finish in the Field
Here's an unusual touch-up problem: sanding to dull a finish down to its original dull sheen, rather than buffing to heighten the sheen. December 8, 2006
Question
I have an installation in which I need to rub some spots on a pre-cat lacquer back to their original luster (dull). These spots have been burnished due to wear. They are on 2' x 4' panels, and the wear spots are typical quarter size or smaller. The spots haven't broken through the topcoat layer.
I tried this technique at another installation on a conversion varnish (dull also) with so-so results. After I fixed the spot with 1500 silicon carbide w/d paper used wet, I rubbed the now overly dull spot with compound, then used progressively duller grits of Micro-Mesh paper (used on their super-cool supplied dense foam rubber block, dry), starting at 12000 grit and working my way down to the approximate sheen. The only reason this technique worked is because the substrate was sanded perfectly flat beforehand. If it wasn't smooth, I would have just knocked the sheen down on the high spots. Can anyone suggest a considerably more fail-safe, luster-reducing rubbing technique?
Forum Responses
(Finishing Forum)
From contributor G:
Is there going to be more rubbing on the same place, causing a repeat of the problem? If not, a shot of Mohawk non-halo dull from a spray bomb should fix it.
From the original questioner:
Sounds promising, but do you think it truly is non-haloing? I forgot to mention that there is lots of direct sunlight on these panels, so it's got to be as close to the original sprayed finish as possible.
From contributor D:
Sounds like Abralon might work well in this situation. It's a Mirka product and is available in a range of grits, from 360, I believe, to 4000 grit. To get a dull finish, I would suggest 1000 grit pads only. On a 5" DA sander, wet the pad thoroughly and surface lightly. Sanding in a circular, not linear, pattern, make 4-5 passes on panel with one pad. Wipe off with paper towel and check results. This has worked well for me in similar situations. Do test panels first to decide final grit to sheen desired.
From contributor M:
Abralon is a good product, but the Micromesh that he's using is a much nicer product. It's used more by hobbyists, especially pen makers (like me when I'm not spraying cabinets). It lasts about 4 times longer than an Abralon pad and comes in grades that are far, far finer than Abralon (not that he needs fine grain here).
You will have a fun time trying to dull pre-cat with an abrasive. The Micromesh would have been my nuclear bomb. The only other thing I might have tried is spraying on a mist of acetone (on some test boards, in the shop) followed by a small amount of paste wax. I use acetone misting to rough any carved or intricate cabinet parts between coats of CV. It dulls it nicely. I haven't tried it on larger panels.
Your last option is to just spray on another coat of dull precat. Scuff it up and shoot it.
From contributor C:
I have recently done a similar repair and I got to a fine satin by hand sanding with a folded Abralon pad at 4000 grit. So I'd guess that you need about a 2000 to 1500 grit to match your sheen. 12,000 is going to get you too shiny. Sand in a crosshatch pattern (up and down, then left and right, then x patterns). Use very light pressure. If you get it extremely close but just not quite perfect, then go ahead and do the whole surface in this way. You'll be good with a slight border to break the comparative edge.
From contributor M:
The aerosols come in many sheens, and they do an excellent job. They are compatible, and they are fast. Be sure that you dewax before you spray.
From the original questioner:
Thanks for the suggestions! Just to clarify: I started with 12000 grit, and worked progressively down to something like 6000 or 4000 (can't remember exactly). Also, I don't know if it matters, but these panels are pigmented, not clear over stain. It sounds like the best way is to spray the area with a touchup aerosol (I'm not going to lug a compressor and gun to their condo!). I've heard Konig has nice products, and think I'll give that a try. (I know Mohawk is big, but I just can't resist the imports!)
From contributor C:
You used your grits backward, then. The 12,000 grit is extremely fine, for penultimate polishing to pretty high gloss levels. There is no reason to use the 12,000 grit at all if you will follow it with coarser grits (the 6,000, 4,000 etc.). The higher the grit number, the finer the cut... Lower grit numbers represent coarser and faster cutting papers.
From the original questioner:
The reason I was going progressively backwards from 12k down was because I was using the logic of regular sanding where you sand with progressively finer paper (150, 220, 320, etc.) Obviously I was creating too much work for myself! Thanks for pointing that out.
I did get a chance to use Konig's regular spray lacquer (not their repair lacquer) on some crown, and it sprays beautifully.
