Replies

1. 
   EdWeber | Feb 28, 2022 09:36am | #1

   Shellac is a sealer, a barrier, a top-coat.
   Why would you use it under oil finishes that are designed to penetrate into the wood, you're defeating the purpose.

2. 
   stantheman | Feb 28, 2022 09:38am | #2

   Is the only reason for using shellac before oil to reduce blotching? Is Osmo prone to blotching? Ive not used it yet so am curious.

3. 
   bilyo | Feb 28, 2022 10:56am | #3

   I'm with EdWeber, shellac under oil defeats the purpose of both. It's a waste of money and time.

4. 
   elmaduro | Feb 28, 2022 11:12am | #4

   Back of the can implies it should be applied on raw wood..

5. 
   _mj_ | Feb 28, 2022 12:53pm | #5

   Never heard of shellac under oil. Oil is an "in the wood" finish, shellac is an "on the wood" finish. I don't see the point of a wipe-on oil over shellac unless it is a wipe-on oil-based poly.

6. 
   mikaol | Feb 28, 2022 02:45pm | #6

   I've been working only with oil finishes for 10 years now. Make a decent living at it, too. So, trust me or don't when I tell you I agree with the others. Besides, the oil won't cure over shellac.
   Mikaol

7. 
   gerrylou | Feb 28, 2022 05:29pm | #7

   Hey Paulsshop and Stantheman,

   For my money straight oil is the best. Nothing matches the look and feel.

   To Stantheman's question, the specific reason I used shellac under Osmo is because a Luthier friend suggested it for a couple of acoustic guitars I built. I don't like spray lacquer and was looking for an alternative.

   Shellac and fine dust from offcuts are part of the pore fill process, which is especially critical on the neck, followed by several very thin top coats of Osmo high solids oil. I had the time so I doubled the recommended cure times between coats. After testing on offcuts, I went for it and I couldn't be happier with the results. I got the super smooth pore filled surface with the look and feel of oil.

   The neck gets a lot of use and I have not had any issues with the oil finish over shellac so far.

   Cheers

1. 
   cl810 | May 26, 2023 10:50am | #15

   How does the appearance change after applying Osmo over the shellac? By chance, do you have any before and after pics?

8. 
   [email protected] | Feb 28, 2022 05:33pm | #8

   I should have been more precise.I used the very thin shellac to raise the grain slightly then sanded with 320.The raised grains with shellac were stiffer than that with water,the shellac dried quickly and allowed almost immediate sanding.I always applied the oil with a white pad and most often rubbed it down with a clean cloth

9. 
   EdWeber | Feb 28, 2022 07:47pm | #9

   Putting an oil/wax finish ouer a sealer (shellac) makes absolutely no sense.
   Oil needs bare wood to penetrate into, if you seal the pores with shellac it can't.
   Applying shellac then sanding it back is just an additional step that's not necessary. If you want the Osmo or oil/wax finish, just use that and follow the instructions.
   Osmo High solids is designed to be applied to bare wood. It may stick to shellac but again, what's the point?

10. 
    jharveyb | Feb 28, 2022 09:53pm | #10

    I think we are missing something here. Many oil finishes are really wiping varnishes (my favorite, Waterlox original, is one such.) Yes, they are thin enough to penetrate raw wood, but they can also be used as a varnish over a sealer like shellac. As long as the two finishes are compatible (and shellac is compatible with almost everything), you can put one over the other. This would give you the mellow glow of a varnish top coat, without the darkening of the wood of a straight oil/varnish finish, which is really not traditional/suitable for a guitar. And better protection than just shellac (in case the guitar is played in a rowdy bar!)

    I recently refurbished a walnut low chest of drawers that my mother refinished about 60 years ago. The top was a crude replacement for the original, so I made a new top. The varnish on the chest was looking a bit past its prime, so I sanded it lightly and added several coats of Waterlox, EVEN THO THE CAN SAID TO APPLY OVER BARE WOOD. I knew my mother had used a traditional varnish; this would not have worked over polyurethane. Since the two finishes were compatible, there was no problem, and the finish perked up nicely. By the way, I used an amber dye on the top before the Waterlox to make it look a bit more aged, like the chest. Walnut is the rare wood that lightens as it ages, rather than darkening,

    
1. 
   gerrylou | Mar 01, 2022 08:44am | #11

   I agree. Also, no two oils are created alike, some shellacs are better quality than others, you can mix your own or get it from a can, and then there is the specific characteristics of the wood being finished.

   The trick for me was to find the right combination of all of these elements to achieve the look and feel I wanted.

   Gonna have to find a sample can of your go to finish and try some out on some offcuts because that chest looks awesome.

   Cheers

   
1. 
   jharveyb | Mar 01, 2022 09:36am | #12

   I've been using the Waterlox Original for many years. There was an article in a recent (last few years) FWW about how to achieve a beautiful mirror finish with it. I have a slightly different routine, and don't try to rub to mirror. My refinished dining table has enough glare when the sun is on it...
   Let me know if you want more info on using it. By the way, their tech support is really good; helpful. You can purchase it from Woodcraft or on-line. I get mine from a wholesale hardware company in Nashville that I have an account with.

11. 
    EdWeber | Mar 01, 2022 10:14am | #13

    wiping oil finishes are nothing more than some type of varnish (poly) a small amount of oil (usually linseed) and a solvent like mineral spirits.
    If you use them over bare wood, the oil will penetrate and then the varnish cures. This is why they usually tell you to flood the piece because once the varnish cures, no more oil can penetrate. You only get one "first" coat.
    If you use them over a top coat, the varnish will stick. but the oil does little to nothing
    They're considered "foolproof", because whatever you use them on, you get some type of result.
    What they don't tell you is that what doesn't penetrate or otherwise adhere to the finish is on your rag. There is a lot of waste with these finishes.
    Good luck

12. 
    MattPL | May 25, 2023 05:06pm | #14

    I often use Cherry in my projects and I want it to look as natural as possible (as opposed to a darkly stained wood). The problem is Cherry blotches, a lot. I have tried many ways to control the blotching. The best method I have found is to use a thin, very clear sealer.

    The best I have found is to use a 1 pound cut of clear shellac and flood the wood, and wiping off the excess ASAP. The idea is that the more porous areas absorb more of the shellac and, therefore, resulting in a wood surface with fairly uniform ability to absorb the finish. I will sometimes apply two coats, not sanding in between. (Because shellac dries so quickly, the second coat can be applied within minutes of the first.)

    After applying the shellac, I lightly sand it with 220 and then 400 grit. This sanding does a few things: it creates a uniform look on the surface, it removes the sheen of the shellac and it exposes the wood on the surface to the finish I will eventually apply, such as Osmo or Maloof.

    Because the shellac limits the amount of the finish that absorbs into the wood, you end up with a finished project that is a little lighter in color than it would otherwise be. (Which I prefer because the grain stands out more.)

13. 
    sjeff70 | May 26, 2023 08:54pm | #16

    I suppose if you’re hand planing to a ready for finish surface you could lightly scrape the shellac before going to the osmo.