Thread: Bol. Rosewood & urethane

I coated a set of Bloodwood and a set of Bolivian Rosewood scales with Minwax Helmsman spar urethane (spray) a couple days ago. They were outside in the cold most of the time, but I brought them inside a few hours after applying each of the 3 coats. The Bloodwood scales are now completely dry, but the Rosewood is still tacky, and has much more of a sheen to it than the Bloodwood does. Is this because of the oils in the Rosewood, that the urethane doesn't like? Would I need to use epoxy instead?

Thanks!

Rosewoods, in general, have oil issues. You can still use polyurethane, but your curing time and adhesion will be poor at best unless you do something about the oil.

Would it do better with epoxy, and should I sand off the urethane before putting the epoxy on?

Originally Posted by MaillerPhong

Would it do better with epoxy, and should I sand off the urethane before putting the epoxy on?

Yes to sanding the poly off.

As to the epoxy, it should work, but there will be two potential problems.

1. The oils may migrate into the epoxy. The oils are generally dark in color and may cause undesireable hazing in the finish. They may also interfere with the surface finish a little. Rippling and fish eyes may occur.

2. The adhesion may be poor. This is normally not a big deal in wood working, but scales move, flex and take abuse.

It is best to soak or wipe the scales with acetone, then let dry before finishing. This will help keep the oil at bay until the finish sets.

Anything in the rosewood family, Cocobolo, Kingwood, any number of region rosewoods will stay tacky forever. I have tried about every finish out there. As a rule I use one of 3 finishes on those, a Danish oil, Epoxy resin or CA. Those are the only things that will dry/harden correctly. I give everything a wipe with acetone before I lay on the finish. It takes off the dust and surface oils so the finish penetrates and bonds better. I have done several sets in Epoxy, never had a feathering or adhesion problem not to say it might not develop in another 10 years.

i love the rosewood and cocobolo. beautiful wood, great grain, and super cool to work with. but yes finishing it SUCKS!!. i had some that the natural oil blocked just about everything i put on it.

use acetone, and either CA or epoxy. the acetone will buy you a little time.

good luck.

vgod

I tried sanding off the urethane, but it just turned into gunk. I used an Xacto knife to scrape most of it off (managed to slice into the wood in a couple places) then an acetone wipe to get the rest off. Re-sanded down to 1500 and wiped with mineral spirits. Applied a sanding sealer, and now they look ready to be sanded again and have the urethane put on.

Well the urethane is tacky again. I suspect I either didn't use enough mineral spirits to get rid of the oils, or I didn't let it dry enough between the mineral spirits and sanding sealer. Guess I'll have to scrape it off and try again tomorrow