Tung Oil Question

[steve-norrell]

I am finishing some walnut and would like to find out if you can apply tung oil over shellac. I would like to apply one or two coats of shellac, followed by one or two coats of tung oil.

Regards, Steve

[Black wallnut]

I think you can but I have to wonder why one would. Unless you are only using the shellac to seal the pores. Tung oil as with most oils works best IMHO as an in the wood finish rather than just a surface finish. It also takes a bit of time to cure. And if put on heavy does not look very good IMHO.

[Uncle Cracker]

Tung oil over stain is fine, but over anything that seals (such as shellac), it doesn't work so well. You want the oil to penetrate the surface.

[natausch]

Shellac is technically a top coat, albeit a weak one when it comes to impacts, water, and time.

Generally varnish is applied over shellac to protect it against, well life.

Nowadays it is often used above a stain to warm the wood, as a pre-stain treatment for difficult woods (maple!) a grain/sanding filler, or as part of a multi-tone finish.

Typically tung oil is used as a stand alone finish, "in the wood" like Black wallnut said. Since it needs to cure there trying to apply it over Shellac will lead to adhesion and curing issues.

The best use of tung oil is to keep the wood looking and feeling like wood.

Couple questions
What is the walnut project?
What is the goal in using shellac?
What is the goal in using tung oil?

[steve-norrell]

Questions answered! My suspicions confirmed.

I had thought of using the shellac to partially seal grain and pores in the walnut, then finish with the tung oil.

The projects are small to medium boxes that will see some handling and the tung oil finish, being easier to refinish if needed, seems to be the best choice. I don't like the appearance of a polyU finish, although a wipe-on, semi-gloss finish isn't too bad.

I will sand down to 220 grit and go with the tung oil.

Thanks for confirming my thoughts. Regards, Steve

[natausch]

As a side note; I've used the General Finishes wipe-on satin varnish over de-waxed shellac to a good amount of success. Then again Walnut is such a great wood on it's own that Tung oil is perfect for finishing.

For future projects I'd strongly advise running test pieces with shellac and/or a wiping varnish I think you'll find that the shellac, cured about a week has enough resistance for casual handling (jewelry box = yes, toy box = no), feels unique and is extremely easy to refinish. It's main faults are no resistance to water or achohol. Adding varnish does take away some of the slick glass texture, but protects the shellac without diminishing the warm look of it too much.

[cabinetman]

Questions answered! My suspicions confirmed.

I had thought of using the shellac to partially seal grain and pores in the walnut, then finish with the tung oil.

The projects are small to medium boxes that will see some handling and the tung oil finish, being easier to refinish if needed, seems to be the best choice. I don't like the appearance of a polyU finish, although a wipe-on, semi-gloss finish isn't too bad.

I will sand down to 220 grit and go with the tung oil.

Thanks for confirming my thoughts. Regards, Steve

Tung oil can be a stand alone finish, as would boiled linseed oil, but not very durable. The BLO will add an amber tone to the wood, while pure Tung oil will not. Using the Tung oil first will bring out the grain and color. It will take longer to cure than BLO. Once cured, can be topcoated with dewaxed shellac which would act as a barrier coat for any film finish you would want to add.

Just a note about Tung oil. If you use it make sure you use 100% pure Tung oil. The finishes sold in the stores that say on the can "Tung Oil Finish" is not pure Tung oil. It's likely to be Soy oil, and have varnish resins and mineral spirits added. The prepared finishes (oil) that have the word "Finish" on the label are all composite media, such as "Danish Oil Finish", "Teak Oil Finish", etc.
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