poly over thinned shelac?

[mark kosse]

Guys, I want to slightly color some pine. 2:1 denatured alchohol and shelac gives me the color I'm after. I know your not supposed to finish over shelac but I'm wondering if it is thinned that much if it would work. You basicly can't "feel" the finish when put on.

Anyone tried it?

Thanks, Mark

[Dave Gaul]

I know your not supposed to finish over shelac but I'm wondering if it is thinned that much if it would work.

Mark, not sure what you mean, but shellac is used as a barrier coat quite often. I've not tried your schedule, but there are plenty of shellac experts around that will chime in eventually. Most are going to tell you to shy away from poly. Laquers & Varnishes (non-poly) are better choices from what I've learned here on SMC.

It is also very common to use shellac as a top-coat, and even add a few coats of wax/polish on top of the shellac. Properly applied shellac leaves a wonderful finish IYAM.

[Prashun Patel]

In general you're not supposed to finish poly or waterborne finishes over WAXED shellac. Over DEWAXED shellac, almost anything goes; it makes an excellent primer/barrier/sealer.

What is the product you used? If it was Zinsser Bullseye, then it's waxed.

You have a couple options:

1) Take your chances. Some people have reported that they've used poly over bullseye many times with no problem. Yr instinct that thinning reduces the incompatibility risk is right.
2) Finish with an oil based alkyd or phenolic varnish instead of the polyurethane.
3) Spray a thin coat of dewaxed shellac (Zinsser Sealcoat is the easiest) over the current surface. Shellac melts into a single layer, so some wax might still migrate to the top, but my NON-EXPERT opinion is that the risk is low.

[Dave Gaul]

I forgot about the Waxed/Dewaxed part!!

[Darius Ferlas]

I had similar questions a few months ago so I called Zinsser. Their tech support told me that Sealcoat will ensure adhesion if a coat below it is pretty much any finish and it will accept pretty much any finish on its surface. That definitely includes Zinsser Bullseye, the one with wax.

They do not recommend poly over Bullseye.

[Chris Padilla]

Zinsser Bullseye SealCoat is a dewaxed clear shellac. I often use it as a final coat.

Zinnser Bullseye Shellac is a waxed shellac available in clear and amber (maybe one other). It can also be used as a topcoat and with certain finishes that don't care if it has wax in it (lacquer is one, I believe).

[mark kosse]

Yes, It is Bulleye. And I should have mentioned amber shelac. The dewaxed would work but the color isn't there, is it? I know I could also overcoat with the dewaxed and then varnish or poly, but it's more steps than I want to take. Thanks

[Jim Finn]

I put Poly over Bullseye
shellac, very often ,with no problems.

[Scott Holmes]

Mark,

You didn't tell us your project... only that it's pine. Amber shellac imparts an antique look on pine.

What are you wanting to finish with this schedule?

Shellac is a great finish and it has stood the test of time. If amber shellac gives you the color you want; that may be all you need.

The amber in the can is a 3 pound cut so mixing it 2 to 1 with DNA yeilds a 1-1/2 pound cut.

FYI: Shellac is not to be built up to a thick film like lacquer or varnish. It will alligator. The perfect shellac finish is the thinnest possible film that is flawless. Shellac is a very hard finish.

Poly is for floors.

[Steve Schoene]

To be picky, equal parts of 3lb. cut shellac and DNA makes shellac of 1.3 pound cut, not 1.5 lb. cut.

But, it is possible to have an amber shellac without wax. You can buy dewaxed orange shellac in flakes and mix your own. ("Amber" shellac is made using common orange shellac flakes--in fact, it used to be that Zinsser marketed this as Orange shellac, and what they market now as Clear used to be termed White, both terms in accord with the traditional trade names. But, presumably folks were confused and Zinsser changed their names.

SealCoat is a blonde shellac, which is a more refined form of orange shellac, with more of the natural shellac dye filtered out. Clear shellac has been chemically bleached, and has inferior properties, especially as far as moisture resistance. SealCoat isn't Clear with the wax removed.

[mark kosse]

Thanks for the replies guys!

Scott, The project is framing out some windows, doors and a cased opening in a farmhouse with lots of pine furniture. Since the windows get cleaned with a ammonia mixture I feel I have to overcoat the shelac with something. The windows are new and the highest efficiency I could find so I don't think I'll have any problems there.

[Steve Schoene]

Yes, you would want to overcoat the shellac, but I wouldn't use poly since the single part poly varnishes are particularly prone to UV degredation. You will have eliminated lots of UV because of the double pane, and low-e coatings, but I'd still go with a non-poly varnish such as one of the Waterlox phenolic/tung varnishes. It will adhere just fine to shellac that still has it's wax, though, since it is a relatively dark varnish might give you a fair amount of the ambering that you are looking for.

[Prashun Patel]

" I know I could also overcoat with the dewaxed and then varnish or poly, but it's more steps than I want to take."

+1 on using a different kind of varnish.

I love Waterlox, but it's expensive and imparts a darker color, which you may or may not want since you've already gotten a color u like from the shellac.

Cabot's alkyd varnish is pretty decent, not as dark, and is readily found at LWS.

Here's another suggestion that will likely get me flamed:

use a spar varnish. Beware it's not a spar urethane. The spar varnish (again Cabots - formerly McCloskey's) is fine. On a softer wood like pine - especially on a window frame, I believe it's a good choice. It's a little softer than straight varnish, so it'll give a little with dings instead of cracking. Some spars also have UV inhibitors.

On narrow pieces that you don't want to rub out to a high gloss, spar varnish is a fine choice.

[Howard Acheson]

Yes, It is Bulleye. And I should have mentioned amber shelac. The dewaxed would work but the color isn't there, is it? I know I could also overcoat with the dewaxed and then varnish or poly, but it's more steps than I want to take. Thanks

You can use a non-poly oil based varnish over standard, wax containing shellac. Works just fine.

[Jerry Olexa]

The key point here is whether your shellac is DeWaxed or contains wax..Then proceed as mentioned above...My personal choice would be to not use Poly as the topcoat in either case. Just my opinion.