Shopsmith Forums

I got a garage sale desk today that is in good shape. Just a few spots that need touching up. But I don't know if it's lacquer or poly. I'm used to having to strip the whole thing not touching up. A internet search brings up conflicting ways to tell what it is. Can anyone help?

It's a oak computer desk made of plywood and solid oak strips. It's either a high end out of the box desk or hand made. Seems to be made within the last 10 years from the looks of the hardware.

I don't have finish the whole thing. There's a few spots about size of quarters or dimes that need fine sanding and restaining. Than clear finish to seal it.

Thanks in advance, Tom

Most commercial makers use lacquer if it is a commercially made desk, most likely lacquer.

I got out my finishing bible out, if you wipe a spot with lacquer thinner or acetone and it gets soft/gummy it is lacquer.

I recently bought Bob Flexner's book Understanding Wood Finishing, and it has a section on identifying an old finish. It goes like this, doing these tests in sequence in an inconspicuous spot:

1. If alcohol makes it soft and stickey, it is shellac.
2. Otherwise, if laquer thinner makes it soft and sticky in seconds, it is either lacquer or water base.
2b. To tell the difference, if toluene or xylene makes it gummy, it is water base.
3. If neither alcohol nor lacquer thinner soften it, it is a reactive finish, which includes polyurethane. Which type usually doesn't matter.

That's already more than I actually know, but the book has an entire chapter on repairing finishes. Not to mention debunking a whole slew of finishing myths.

BD,
That is my bible second edition, I learned so much from it!!!!!!!!!!!!!!

Acetone not only softened it, but some of the stain was removed. So it must be lacquer.

I'm thinking of steel wooling the bad spots, spot stain for color matching then light steel wool the whole desk with #0000. Then spraying lacquer top coat over the whole desk.

Any thoughts?

Thanks for all the help, Tom

Acetone will attack many finishes. Try lacquer thinner to be sure. If it is lacquer, you could use steel wool soacked in thinner and blend the finish, and then topcoat with new lacquer. Do this outside or the fumes will be very very bad!