polishing polyurethane to a satin finish

[Eric Schmitt]

I need some advice on polishing out a polyurethane finish to a semi-gloss/satin finish. I'm not going for a high gloss mirrored finish, I want more of a low gloss satin finish but not sure how to go about it. I usually do oil finishes, this will be my first go with poly. For my oil finishes to achieve a satin finish I just level sand with high grit sand paper or 0000 steel wool then lightly buff with some sheen conditioner. I google searched and came across a similar method that was basically 1) Level sand with 600 grit wet sandpaper, 2) Load up a pad of 0000 steel wool with paste wax and hand rub, 3) Remove wax residue with clean cloth or shop towels. Will one of these two methods work out fine or should I be going about this in another way?

[Michael Lewis]

You start by buying satin finish. Finishes are formulated to provide various degrees of flat / gloss. Actually, gloss finish is easier to make look good because you can sand and buff until it looks good. Satin on the other hand is sprayed and that is how the surface texture forms. Your surface preparation must be perfect, and you must spray an even coat for the final coat, and let it dry. You can't fix flaws in satin finish or the area becomes a bit more glossy from being touched and rubbed.

[Brad Heinzen]

Yeah, if you try to achieve a matte finish through manipulating a scratch pattern, it'll get shiny wherever you inadvertantly polish it up through handling. If you use a finish with some sort of flatting agent in it, the sheen will likely stay more consistent over time. I've always found anything flatter than a medium rubbed effect to be tough to do. As Michael says above, what you get off the gun is pretty much what you get. With some medium rubbed effect finishes, you may be able to get away with a little bit of buffing with fine steel wool, but that's about it.

[Eric Schmitt]

Thanks for the help. Re-reading my question, I think polishing was the wrong word for me to use. What I was trying to ask was how to level the finish without leaving all kind of scratch marks in it and not buff it to a shine. I sprayed up some test pieces and have been playing with that to see what works best and I think I got things figured out. What I find is working best is:
1) using a semi-gloss rattlecan poly
2) spray my coats to build up the finish
3) sand level with 320 grit paper (carefully as to not sand through the finish)
4) spray one more coat & let dry
5) using no more than the pressure of the weight of your hand lightly rub with 0000 steel wool going with the grain to knock off any overspray
6) lastly a quick and light rubdown with birchwood casey sheen conditioner

This method seems to give me the the finish I'm going for... no gloss, no shine, no scratches, just a clear level protective finish that highlights the grain of the wood. Again thanks for the advice, I'll post some pics of the guitar when it's all finished up.

[Joel Nowland]

Eric

many years ago, while doing antique restoration, we used a product called Wool-Wax or Wool-Lube. It's not wax. It comes in a thick liquid or gel.

It's designed as a rubbing lubricant for 0000 steel wool to clean and produce a satin luster on old furniture rather than refinishing. We also very often rubbed out entire pieces of furniture which we built or refinished.

Spray with a satin lacquer, sand flat to 800 grit and then rub in long straight strokes with the 0000 steel wool coated with the wool-wax.

Looks and feels silky smooth.

Joel

[David King]

Here: http://www.mohawk-finishing.com/catalog ... ictNbr=243
It's water soluble and leaves no residue.

[Beate Ritzert]

Quite recently i have been using Micromesh in order to sand to something non glossy (wet sanding!) - in this case it was on ageing pieces of celluloid. A satin finish can be achieved by stopping the sanding process at a grit between, say 4000-7200, dependent on the degree of satin gloss You want to achieve.

Some weeks ago i finished a guitar where i was actually using glossy polyurethane acrylic laquer and went up through all steps up to 12000 in order to achieve full gloss. During the steps above grit 4000 something like a satin finish had developed in this example as well.

At least for my limited skill it is easier to achieve an even satin gloss with Micromesh than with steel wool.

[Barry Daniels]

Be aware that steel wool does not do a good job of leveling the finish like sandpaper does. You will end up with very minor undulations in the surface which will be visible when the light is reflected at certain angles. Not a deal killer, but something to be aware of.