Laquer - Rubbing Out

[David Justice]

So, I made a chessboard for a friend and wanted to rub out a nice satin finish. I put 10 coats of spray Laquer and left it for 3 weeks. Today I used 320 paper with some soapy water to sand down the high spots, then used 800 wet sandpaper with an ROS to get to a satin sheen. Now that it has been cleaned off and dried, there are spots that look quite different from the rest (tried to take a picture, attached here). These spots are very dull and almost look like wood when it gets wet.

Is it possible that I sanded through 10 coats of laquer? If so, how can I fix this? Can I add more laquer and start over.


Thanks for any help!


IMG_7217.jpg

[Patrick Chase]

It's a little hard to tell from a picture, but that certainly looks like you've cut through. If so then I would strip to bare wood and start over.

If the finish were thinner to begin with then you might be able to put more coats on top of the cut-through and achieve reasonable uniformity, but I don't see how you can do that with a finish that presently varies between 10 coats and nothing.

Did you happen to check the wet film thickness that you were laying down? If so what was it? Also do you know what your lacquer's solid content was after any thinning?

[Doug Hepler]

David,

To answer your question directly, yes. It is possible that you sanded through 10 coats of sprayed lacquer. You mention high spots. By the time you get to leveling the finish, there should be no high spots. To get the finish that I assume you want, you needed to level the bare wood using the same procedure that you would use later to level and rub out the finish. In my case, that would be a cork or wooden block, working through the grits to completely flatten the top, stopping at about 220 on bare wood. Leveling and rubbing out are (IMO) hand operations. Hard to say what the ROS did. Sandpaper lubricated with water (soapy or not) is a bit more aggressive than you may think, and sprayed lacquer may be thinner than you think.

Apparently, you did not apply dye or stain. You should be able to flatten the wood and then re-apply finish coats without any of the "history" showing on the finished board. After your next to last coat, scuff sand with 800 grit (or so). Then apply the last coat and rub to a satin finish with pumice or 0000 steel wool.

I have sanded through finishes more than once. I have never rubbed through a finish with steel wool.

Doug

[David Justice]

It was spray can laquer, I should have said that to begin with, so I really don't know the thinness. I don't usually do this, I'm a furniture guy. Thanks for the help. I will sand back to wood and try again to just put on a topcoat and rub with steel wool.

Thanks!!

[Patrick Chase]

Leveling and rubbing out are (IMO) hand operations. Hard to say what the ROS did.

I meant to say basically the same thing but forgot. Typical dry film thicknesses are on the order of a few thousandths of an inch, so there really isn't much margin there for variation in sanding. Like Doug I level and rub out by hand, keeping careful track of how much I've worked each area. Also and as Doug says, the wood needs to be flat to begin with, or at least close enough that your sanding block will "follow" any variations.

Doug's process of leveling, then applying a final coat, then rubbing is generally good advice, and mandatory with reactive finishes like varnishes that show witness lines when you sand through the boundary between one coat and another. With nitrocellulose (solvent-based) lacquer and shellac you can get away with leveling and then rubbing out all in one go, with no coats in between.

[Wayne Lomman]

Spray can lacquer can be anything. It may be lacquer in name only. Go on with coating and see if it blends in. You will know in a coat or two. If it doesn't, start over. Sand the job flat as often as possible at each coat so that you are not trying to do so much in one go.

As already said, levelling and rubbing out are hand jobs. Machine sanding is best left for high build primers.

If you want a low gloss finish, apply a low gloss product. Dulling off a gloss product is a mugs game. Lower gloss coatings are also easier to sand as the flatting agents assist with sanding. If you are worried about bits dropping in your finish, lean it against something and spray a 60 degree surface. It will cure better as well. Getting out steel wool and 800 paper is not required to achieve what you want. Cheers

[Doug Hepler]

David,

You wrote, "just put on a topcoat." I was suggesting that you re-apply multiple coats. Maybe you could rub through one coat of spray lacquer even with steel wool.

Patrick -- good point. I was actually describing my (Flexner's) schedule for brush-on varnish. But as you said it's generally good for shellac and lacquer also.

Wayne -- what is a mug in Australia? In my parlance it is a tough and somewhat brutish man. I think you meant an unskilled person? as in rubbing out a gloss finish is a fool's game? I am asking to learn a better way. I have avoided "satin" varnishes for years. I apply clear gloss and then rub out with steel wool, pumice and/or rottenstone. Not only does it look great but it has a sensual touch that makes my clients quiver with pleasure. But I'm a hobbyist and my clock ticks at a different rate than a pro's.

All the best

Doug

[Patrick Chase]

Wayne -- what is a mug in Australia? In my parlance it is a tough and somewhat brutish man. I think you meant an unskilled person? as in rubbing out a gloss finish is a fool's game? I am asking to learn a better way. I have avoided "satin" varnishes for years. I apply clear gloss and then rub out with steel wool, pumice and/or rottenstone. Not only does it look great but it has a sensual touch that makes my clients quiver with pleasure. But I'm a hobbyist and my clock ticks at a different rate than a pro's.

His argument is that rubbing a gloss finish with coarse abrasives to achieve a satin look as the OP did is a fool's game. One obvious problem that hasn't been mentioned is that over time the roughness that you impart by abrasion will wear down, and the surface will become glossy. I would imagine that the squares corresponding to standard opening moves would "re-glossify" first on the chessboard, for example.

I don't think that anybody would debate that if you want the best possible gloss finish then rubbing out is the way to go. I know people (not me) who can get reasonably close by flow-coating a sprayed finish onto a leveled surface, but even so a rubbed finish looks and feels better.

[Wayne Lomman]

A mug in Australia is not necessarily a fool. It more relates to the feeling you get when you find all the good jobs are taken and you are left doing the thankless, tedious work probably because you turned up late. It can be an insult but not in this case. It's one of those Australian vernacular words that have range of meanings.

Rubbing back gloss to satin is a perfectly acceptable technique. It's just not an easy way. If your elbow and wrist can take the work, that's ok. Mine can't since about 30 years ago so I have adapted all my techniques to minimise strain on those joints. I hand sand as needed at every stage of polishing.

Getting a good gloss off the gun is quite achievable if you use good products and manipulate them correctly. For me, this means paying $30-70 per litre. Satin finishes are more in the $15 per litre range but again a good quality product that lays down as it should. Cheers

[Rob Luter]

May I suggest a different approach? After you sand everything back to bare wood, apply a couple coats of BLO or Danish Oil to get some finish in the wood as opposed to just on the wood. This will result in a velvety satin finish you may just want to stick with. It's easily renewable as well. If it's not your cup of tea, you can always apply a clear topcoat over it.

Here's an example on maple. Watco natural Danish Oil.