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I searched the messages, but I still have some questions on varnish
or water-based polyurethane (Crystal-Lac) over shellac.
I am in the process of finishing a coffee table. I applied one coat of
Watco danish finish, and now I’m in the process of coating that with 3
coats of Behlen orange shellac. Since it’s a coffee table, I thought I’d
coat the shellac with varnish, alklyd or water based. In reading past
responses, it seems I might have a problem with adhesion to the
shellac. I don’t know if it’s dewaxed or not.
What has been your experience with varnish over shellac? Should I
stay away from a water based poly? I think I need some protection,
because drinks will be put on the table…
Thank you
Replies
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You may have yourself in a real bind here. You are correct that varnish will have decreased or no adhesion to shellac unless it was dewaxed. If the product you used does not specifically say "dewaxed" is isn't. In addition, applying a waterbourne product over shellac is not a good idea either. A general rule is not to mix types of finishes on the same surface.
What I would do, it remove the shellac from the top surface and then finish it with oilbased varnish or poly.
*Thanks, Howard, I was afraid of your response. I guess I must have read about dewaxed shellac as being OK for a varnish top coat.I'm not looking forward to stripping down the top...Wonder if I can topcoat with dewaxed shellac, then have a go at varnish?
*hi verne. don't use water base as indicated above. make a sample piece with the process you used thus far. let shellac dry 24 hrs. sand with 320 grit paper, then try one of two options- varnish as planned or try lacquer. let dry 24 hrs. test for adhesion by scoring an X with a sharp utility knife in the top layers, apply packing tape and pull up. I think you will be fine with the varnish personally as long as you have prepped the project well-allowed the stain to dry and sanded between coats of finish. good luck
*Verne, I have heard of problems with water based poly peeling when it is applied over shellac. Before I knew about this I finished a cabinet I made with a few coats of shellac (Bull's Eye white)and topcoated with WB polyurethane (Minwax). Its been about a year and I have seen no ill effects. I might add that this is a bathroom vanity. I can't say that the finish will never peel but it has held up so far in less than ideal conditions. I used the shellac only to give the oak a some color, and the poly as the protective finish. Good luck with whatever you decide to do with your table.Bob
*I don't know about overcoating with dewaxed shellac. Shellac is the type of finish that "melts" the underlying shellac finish. Therefore, the wax in the underlying coats may come to the surface.Here is another suggestion, go to Jeff Jewett's website at: http://www.homesteadfinishingprod.com/ Go to the forums and post your question.
*Howard, great suggestion. I posted a question and Mr. Jewitt kindly answered. He said that he has experienced no problems with alklyd based varnish or laquer over shellac that has wax, so long as the shellace surface is scuffed up with 240 grit sandpaper, for a mechanical bond.There will be problems with water base or poly, however. Just to be safe, I ordered some wax-free orange shellac.Thanks for the feedback.
*I think you are creating more work than is necessary. Shellac should be regarded as the final finish for a project (other than for a good waxing with a high-carnauba content blended paste wax). If poly is more appropriate for the project due to durability concerns, then simply use poly to start with.The project that you have described sounds very nice. Wax it with Liberon Professional paste wax for three coats, put some nice coasters on the table and you're done.
*Yeah, I thought about a shellac and wax finish. But my wife brought up the "cringe" factor. We have 3 children, and we entertain friends with small children. Probably every table that's able to hold a glass in our house has had a spill. I don't want to cringe anytime someone puts a drink down, so I think I need the varnish top coat.I love the look of orange shellac over cherry! If you get a chance to build a cherry project I highly recommend it.Thanks for the thoughts...
*Hi guys Id like to do a rub-thru finish with a red undercoat and a black topcoat. The piece Im doing had been stained and varnished. I stripped the varnish wiped it down with thinner and scuff sanded. Should I put down a primer first? Then what is the best way to achieve the rub-thru effect Thanks Kevin
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