Danish Oil on top of Shellac? - Question of the Week

September 21, 2008 by loglad
Filed under: Finishing, Question of the Week 

This week’s question comes from Eric in Canada who asks: “I know you like to use dewaxed shellac and transtint for a bit of colour, and finish it off with General Finishes. GF is extremely hard to find here in Canada. Dewaxed shellac and the transtint is pretty easy to get. I was wondering if I can use Danish oil on top of the shellac?”

And here was my response:
The only problem with Danish oil in this application is the fact that most Danish oil contains a high amount of oil. That oil will have difficulty curing on top of a pre-sealed surface (from the shellac). The General Finishes products are mostly varnish, if not all varnish (Arm-R-Seal). So what you are really looking for is a simple wipe-on varnish to put over top of the shellac. Minwax sells a decent one that is widely available. A few light coats should do the trick.
You might also consider using a different coloring agent. Even though I do occasionally use a dilute shellac/dye solution for coloring, its only for certain situations. In most cases, I do my staining with water-based dyes or gel stains. Neither of these really seals the surface and you should have no problem following up with a Danish oil if you use them. So really, the sky is the limit for your combinations of coloring agents and topcoats. But to directly answer your question, you want to avoid putting oil/varnish blends on top of sealed surfaces.

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Comments

7 Comments on Danish Oil on top of Shellac? - Question of the Week

  1. Conrad Bennett on Mon, 22nd Sep 2008 7:14 am

    2. Hey Marc this is actually a question for Eric who asked you the above question. I am also from Canada and feel Eric’s pain in trying to get certain finishes / tools etc. Eric mentioned that he can get dewaxed shellac and transtint….I live in Ontario Canada and can’t seem to get the “seal coat” shellac. Could you give me Eric’s e-mail so I could in touch with him and find the shellac?

    Thank you

    by the way, get on with the gadget station I can’t wait to see how it turns out!! :)

    Keep up the great vids!!!

    Conrad

  2. Gatorbait on Tue, 23rd Sep 2008 10:43 am

    3. Marc, based on VERY recent experience I agree whole heartedly with your assessment. I did just that. I tried to put Watco Danish Oil on top of my sealed (with shellac) Mahogany. Arg!!!!! It has been a week and the wood is still bleeding. Will it ever dry? What steps do I take to remove the Danish oil and sealer? Is that even possible?

  3. Denny on Tue, 23rd Sep 2008 11:28 am

    4. I have to admit that finishing has always puzzled me. I thought I understood Marc’s explanation and it made sense. But now I’m confused.

    In Tom Lovino description of his Fujiwhara chest, he states “… I sealed the entire piece with 1# cut of Seal Coat, followed by a buffing with #0000 steel wool. Brushed and vacuumed the thing off, then hit it with three coats of Watco natural, sanding between each with 400 grit paper….”

    Didn’t Tom just use Watco Danish oil on top of shellac?

  4. thewoodwhisperer on Tue, 23rd Sep 2008 11:50 am

    5. Gator- Sorry to hear about that man. Here’s what I would do. I would probably wipe the surface down with denatured alcohol. This should cut through any surface oil and hopefully start to dissolve the shellac below. I would rub the surface rather aggressively and remove as much shellac as possible. Let it dry. Within an hour or two, the surface should be very dry to the touch. At this point, sand the surface. You can either sand back to bare wood, or leave the surface partially sealed, depending on how much shellac is still in/on the wood. Now this leads me into Denny’s question.

    Sealing wood is not an all or none event. Wood can be partially sealed. Think of the grain like a filter. The more sealer you add, the more clogged up the filter gets. And eventually, nothing passes through. So sealing the surface as Tom did, with a 1# cut of shellac only partially seals the surface. Furthermore, the subsequent steel wool buffing removes even more of the shellac, leaving you with a glass smooth surface that will still be able to absorb some finish. But there is a fine line here. If Tom used a 2# or 3# cut, he may have had some curing issues. But there are a lot of variables at play here including the cut of shellac, the properties of the wood itself, and how much you sand the initial layer of shellac. It also depends on just how much oil is in your oil/varnish blend. The less oil in the mix, the better your chances are of quick and easy curing.

    Hope that explains it a little better.

  5. Denny on Tue, 23rd Sep 2008 4:06 pm

    6. Marc, thanks for the explanation. I had the idea that sealing with shellac was an all or not event. I didn’t know that you could partially seal the wood. Once again you have demystified the art of finishing wood for me.

  6. Eric Pellerin on Tue, 23rd Sep 2008 6:50 pm

    7. Finding the Bull’s Eye Dewaxed Shellac in Canada, or at least in the Edmonton area was very difficult.
    I bought 2 lbs of raw dewaxed from Hock Finishes http://www.hockfinishes.com/ with no delivery problems. As for the Transtint, I purchased it from Rockler again with no delivery problems.
    After I placed my order I found company in Sasktoon Wood Essence http://www.woodessence.com/ they have a large selection on dewaxed shellac and dyes.

  7. Tom on Tue, 30th Sep 2008 11:42 am

    8. Yeah, I did seal the project with shellac and then topcoat it with Danish Oil. And, it worked… for a couple of reasons…

    1) The shellac is a very thin cut. I took Zinnser’s Seal Coat and cut it half and half with denatured alcohol. So, we’re talking ‘washcoat’ strength - not a real heavy duty film finish.

    2) I did buff off all the stuff that was on the surface (Leaving the stuff in the pores in the process) with some #0000 steel wool. That basically removed most of the shellac right there.

    The result was that any ‘end grain’ that came wavy to the surface was sealed, but the long grain was not. When the oil hit the wood, the absorption is controlled - a very nice thing to have happen on blotch prone woods.

    The key here - as Marc alluded to - is to buff the hell out of the shellac before you attempt to apply the final finish…

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