Just made a piano bench to accompany a 120 year piano. Piano is mahogany and dark. My bench is turned white oak with a seat of Ash plywood framed in white oak around the edges.
I have tested the white oak with a red mohogany stain and then another dose of provincial…seems ok,..not perfect but ok. If I use shellac will it darken it more. Amber or clear? Can I then top coat it with poly or laquer. ?
thanks
Replies
Use poly over shellac only if it has been dewaxed -- either by you or the manufacturer (Zinnsser SEAL COAT).
cutawooda,
As nikkiwood said, you can use shellac under poly (POLY? Yeeechh!) so long as the shellac is de-waxed.
As for which shellac: shellac comes in about five or so "colors." Depending on how much the raw shellac has been refined, the color runs from a dark, almost chocolate brown, to almost water-clear with just a touch of strawberry. It's easy to use different shellac colors to modify the color left by your stains or dyes. All are available de-waxed.
The degree of refinement makes no difference to the quality; only the color varies. The least refined shellac makes a gorgeous finish.
As you probably already know, don't buy shellac ready-mixed at the hardware or paint store. Mixed shellac has a shelf life of no more than six months (though I've heard anecdotal evidence that the paler colors last longer). I've not yet seen a date on a can of ready mixed, so there's no telling what you're buying. Shellac flakes will still be usable long after the next ice age.
Alan
Alan all of the Zinser shellac i buy thats precut has a date label on the bottom of the can. No date codes, just a plain date the one i bought a few weeks ago ha 07/24/2004 on the bottom.
WmP,
I'm glad to learn that. At last some honest dealing by putting a date on the can.
The advice still holds though. Mixing your own you can mix any cut you want, mix no more than you need, and can choose more colors--unless they now have more than blonde and orange redi-mixed.
BTW, was that the date of manufacture or the expiration date?
Alan
Date of Manufacter Its up to you to figure out when its bad. FWIW you usually have to look in the back because the store puts the old stuff out front. The local builders supply has a can thats probably four years old, i get a chuckle out of that every time im in the paint isle.
WmP,
Excellent. That's definitely a large step in the right direction. But as you pointed out, there still lies a trap for the less than educated: viz, with the ancient can, without an expiration date they make the customer responsible for knowing when it's too old.
Alan
Edited 9/14/2004 5:26 pm ET by Alan
Zinser Bullseye, light shellac states directly not to use it under poly. Also, it is opaque after it is stirred. Dewaxed shellac is clear.
Has anyone ever used this shellac under a thinned out poly? I have my doubts this will work.
Frank
The Bullseye does contain wax, and should therefore not be used under poly, which I think you know.
No, I haven't tried it myself, but it might be interesting to see exactly what would happen if you took 3 scraps and used poly over: 1) fully stirred Bullseye, 2) Bullseye that you dewaxed yourself, and 3) the Zinsser Seal Coat.
Polyurethane varnish has a low rate of adhesion. Therefore, it should not be used on top of a shellac that has not been dewaxed.
That said, it is relatively difficult to dewax Zinsser's shellac. They use a process when making their shellac that adds to the shelf life. The wax settles out of their shellac very, very slowly and sometimes, not at all.
Best to purchase the Zinsser Sealcoat. Sealcoat is a 2# cut of blond shellac that is completely dewaxed. Sealcoat and the Zinsser spray can shellacs are their only dewaxed products.Howie.........
How are you applying the finish; brush or spray? If you want to add a little color and depth to the finish there are a couple options depending on your application technique.
Paul
Furniture Finish Wizard
OK OK OK...I will forego the poly over wax. My main criteria was to achieve an older look to the new piano bench. If it is this much of a problem maybe I should either go striaght poly or straight shellac. Was was their most likely finish 120 years ago...shellac?
I couldn't find the sealer so I just decanted some shellac. I think it will work fine.
Frank
120 years ago the finish was most likely boiled linseed oil or tung oil, possibly a mixture. The piece may have been rubbed with a mix of linseed oil and brick dust -- that's one of the things that gives old mahogany pieces the lovely reddish colour -- although that was more commonly used earlier than that.
Shellac may have been used as an undercoat. Some cabinetmakers used shellac as a primary finish.
You might consider Tried & True polymerized linseed oil finish.
http://www.triedandtruewoodfinish.com/
Good luck.Leon Jester
Roanoke VA
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