I’m a bit confused about what, if any, oil finishes can be applied to a surface treated/sealed with shellac (dewaxed from flakes).
My thinking is if Shellac seals the wood then an oil finish applied on top of the Shellac – such as a Danish Oil or a Tried and True varnish which is basically linseed oil – won’t penetrate the wood as intended. Is this correct?
If so is it ok to apply the Danish Oil first and then, once cured, seal it with a dewaxed Shellac? I like the darker tone Danish Oil imparts.
I’m new to Shellac and so I’m giving it a try using a super blonde dewaxed shellac (from flakes) on a set of White Oak drawers.
Any wisdom is much appreciated.
Replies
I have never used or seen a oil over shellac finish, it would not be very different than oil over varnish which does not seem right. I have used shellac as my main finishing ingredient for over 40 years and for a lightly used piece of furniture such as a chest of drawers or a side table, I used shellac, pale or amber regardless if it has wax or not and over coated it with a wax finish and these pieces are still round in my house after 40 years with their original finish.
To answer your questions, yes and yes.
Oil over shellac does not work.
Make sure the danish oil fully cures before you apply the shellac over it.
You can put an oil varnish blend, such as Waterlox or similar over a thin coat of shellac. The only reason for doing this I would think, is to get a quicker build if that is want you want. I had an acquaintance that used this on all his work successfully. Personally I wouldn't bother.
I have used a very light coat of oil under shellac to "pop" the grain/ figure and bring out a bit of color.
You should always make up a finish sample to be sure there will be no problems.
What are you trying to accomplish? Inside the drawers, or just the front?
The "Shellac and Oil Finishes" and "Oil-Varnish over Shellac" related posts shown to right your post are also good reads on this subject. Good luck with your project.
I'm contemplating the finish for the outside of the drawers front, back and sides.
Thank you all for your kind assistance. It's much appreciated.
Mike Pekovich has several very good videos and articles and there is a video workshop on finishing on this site that covers Shellac but the search here is so bad that finding any of it is mostly luck. If you can't find anything here or want to learn more, go to the Lee Valley Tool website and search Shellac. When the page comes up with all the products, at the top of the page you'll see buttons for products, articles and videos. The video is all about shellac and pretty good. Tom McLaughlin has some good videos on YouTube on his Epic Woodworking channel. I use Shellac on the inside of all my drawers.
It's really handy stuff but does have a little bit of a learning curve. Good luck, be safe and have fun,
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Thank you Rusty Tools. I will definitely check them out.
Cheers
I just finished making a box for a friend. Mahogany and maple. I applied spray shellac thinking that it would work like a sanding sealer. I then sprayed Varathane oil polyurethane over top, and it never dried! I sanded it down to bare wood, sprayed again, and it still wouldn't dry after 36 hours. I ended up sanding it again, and spraying it with water based poly. Not very happy with how that leveled out, but I was in a rush and my friends weren't concerned.
From the responses here, I'll have to look more into finding a better finish to use as a sanding sealer.
If you think about finishes in a couple of contexts, it may help. There are penetrating finishes that soak into the wood pores and hardens below the wood surface. There are also surface coatings that lie on the surface of the wood in the form of a thin durable coat. Shellac can be used as a finish in its own right or as a sealer. So, it is a surface coating. Oils on the other hand (like tung and citrus oils) penetrate the timber. Synthetics like poly finishes are usually surface coatings, but not always compatible with shellac because it bubbles and lifts. Another type of finish possible to consider are the wax finishes like hard wax oils and bees wax finishes. When you stand in front of the finishing shelves in your local wood shop, it is easy to get confused. I think about how durable I want the finish to be on the project I am working or, clarity or color and natural or synthetic. There is usually an answer in there through that maze.
I guess the question is what you are trying to achieve with either of the combinations you mention above. You can apply T&T over shellac, the mfg even "recommends" it (they recommend using their product with everything). You can also use shellac over or under Danish oil. If the former, the oil needs to be fully cured before applying the shellac; if the latter, the oil won't penetrate very far as you said.
If you're using oil to pop the wood's figure, may I suggest 100% pure Tung oil. It too, needs to fully cure--at least a week--before you seal with shellac. I prefer it as I know exactly what I'm getting. No driers, thinners, or proprietary noxious blends, it smells good and is even food safe. If you want to darken the wood, use TransTint dyes before the oil, or you can add it to the shellac but your color will sit on top.
Sorry for the length, hope it helps.
Thank you for your helpful comments and experiences with Shellac.
As was mentioned above, a common problem people have when applying one type of finish over another (oil over shellac or vice versa) is applying the second finish too soon. Manufactures add driers and other things to allow us to handle or recoat projects earlier. They may feel dry but are weeks from being cured. Shellac and lacquer are evaporative finishes and don't cure by chemical reaction like oils. Unlike oils, they can be dissolved by adding their solvents again (lacquer thinner or alcohol). If you apply a heavy coat, the top may feel dry but may take a long time for all the solvent to evaporate. Too many heavy of a coat will take months if ever to completely dry.
I'm not a big fan of rattle cans. I always wipe on a couple of thin coats of shellac, give it some time to flash off, lightly sand and wipe a final coat if I'm only using shellac. If I'm putting another finish over it, I'll give it a day or two to dry well before I finish it.
Sometimes, old shellac or oils doesn't seem to harden very well. I usually don't by any more than I need for the project I'm working on and if I don't use it in a year or so I'll send it to the local recycling center. When I did construction work I would keep the left over finishes incase someone needed a touchup on something we did. I made a laundry table for my wife and grabbed a bucket of paint that had been used on a job a few years earlier to finish it. It dried in a normal amount of time but never really got hard.
Use fresh material, thin coats and give it time to dry between coats. Out door weather can effect the drying time of indoor projects too.
Good luck, have fun and be safe.
Interesting responses. Oil based finishes over a sealer (shellac or other) is nothing new; it works fine. The behavior is similar to the second coat of an oil based product without a sealer.
There may be no 'burn in' depending on the products used (alcohol based shellac and oil based varnish for example) so surface prep between coats of different materials is important as always. I agree that pure oil finishes like BLO or real tung oil are not a good choice over a sealer. Oil blends are fine. I have pieces with this protocol that are decades old and still going strong.
That being said, you are correct that the penetration of the oil based product will be restricted. That is often the reason for using a sealer. Other good uses of a sealer are blotch reduction, compatibility issues, and color (absorption) matching for irregular or end grain finishing.
I frequently put on a few coats of shellac to seal up the surface, give it a very light sand, then proceed with Arm R Seal. The few coats of shellac are much faster and less prone to drips, runs, etc. because in effect it reduces the number of coats of Arm R Seal needed to get the finish I want. Instead of 3 coats of Arm R Seal (with a day or two in between, and all the inevitable stuff falling into the finish because it stays wet for so long) on raw wood - it is now 2 quick coats of shellac (de-waxed), a a very light sand, then 1 coat of Arm R Seal. I am done in 2 days.
Otherwise - if I plan on sticking with shellac only, I apply a few additional coatings (until I get the sheen, grain filling desired, ...), with very light sanding in between each additional layer.
I use Sealcoat - the Zinsser brand of dewaxed shellac- mixed 1 to 1 with alcohol pretty much like the previous poster (dberk). Except I have followed up the shellac with Waterlox, Osmo Polyx or Minwax quick dry polyurethane at various times. The shellac application makes it so that only a really thin coat of the final finish product is required. And the thin coat seems to dry / cure within hours so much so that I can often apply a second coat of the finish on the same day.
At the moment my favorite follow up to a few coats of shellac is the Osmo Polyx satin. It is amazing how a tiny little amount of the Osmo covers a large surface area once shellac has already been applied.
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