I am trying to finish an ebony veneer table top. I read up on finishing oily woods and decided to wipe the surface generously with acetone then immediately seal with three coats of de-waxed shellac (1lb cut) before applying a thin coat of wipe on poly. Despite all this the poly is still slightly tacky in spots after 3 days. Any suggestions?
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Replies
FWIW,
The acetone probably did it's job as did the shellac. I would look to the poly and your drying conditions. Summer humidity?
Ebony, as compared to some others like Teak, is not all that oily to start with.
Boiler
Thanks for the response. Have several other items all finished with poly at the same time and all dry to the touch in 12 hours. Definatly something about the ebony. Have seen the same thing with rosewood, but the shellac seems to do the job in sealing in the oils.
Whats wrong with doing it in shellac? The finest violins and antiques are finished in shellac because it gives a beautiful deep finish without looking plastic.
It's insanely easy to apply. etc..
This is going to sound paradoxical, but you might try putting the table in a humid location. Polyurethane polymerizes in conjunction with water in the air - some humidity is required to speed the reaction.
I had a similar problem with poly and African Blackwood. Despite a shellac barrier coat, just wouldn't set up. Stick with shellac, and maybe try lacquer if you want a different topcoat.
On the other hand, the ebony plugs in my table seem to be ok, I used the watco wipe on poly (after shellac) which is VERY thin. That might be the answer. Wipe off as much as possible when applying and use EXTREMELY thin coats (can't stress that enough).
Good luck.
Chris
a hobbyist's journey
Where is Steve S when you need him? I would go with what Frenchy said which is what I do now with Ebony veneer, use shellac. I did a large kitchen with this stuff, I tested poly on a piece of scrap and had the same results you mentioned.
For the kitchen I used catalyzed lacquer. On smaller projects I prefer the shellac.
Tom.
I've been lurking, trying to find something that really made sense. The shellac ought to have sealed any oils from the ebony. I do assume that the acetone was fully evaporated before shellac was applied. Given the speed that acetone evaporates you'd really have to be fast to miss on that point. It ought to have worked. I'd generally use roughly 2 lb. cut but that shouldn't have made a difference here. Frankly I was hoping the o.p. would come back and report it had finally dried satisfactorily.
But, if it still is at all questionable, stripping off the varnish would have to be done. I'd try using mineral sprits or turnpentine first just to see if it's cure was so retarded that stripper wasn't needed.
Going forward, I'd still use dewaxed shellac, making sure it was freshly mixed, or if Zinsser, WELL within the use by dates. Since there were problems even though the acetone wash was used, I think I'd avoid it. It is a somewhat controversial issue, with some experts saying it just stimulates faster reemergence of the oils.
This is definately a case where a test on scrap would have been quite desirable. Frankly, I'd go with shellac as the entire finish if at all possible. Just think what French polished ebony could look like, though shellac polished by rubbing out will still give a very lovely look.
If the use absolutely mandated a more protective finish, I'd avoid polyurethane due to it's greater sensitivity to suffering ill effects from substrate problems. Also, I'd want the clearest finish I could find, and one which would rub out the most evenly since ebony will reveal haze or defects more quickly than a light colored wood. I'd choose a phenolic resin tung oil based varnish for maximum toughness with good rubbing properties. Behlen Rockhard would be excellent.
A large ebony veneer kitchen must have given the lighting designer a challenge. Could have been spectacular.
Heres a few shots.
Very impressive.
I AM NOT a finisher.
I canot afford Ebony,, But I had some given to me.. Worry about the other wood! Ebony just likes some buffing...
Ebony just likes some buffing...
There are a lot of nice woods like that. Pink ivory, bloodwood, lignum, and on and on. They can be polished to wonderful shines even without finish.
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