Oil Finishes
A few facts on tung oil and linseed oil finishing products. May 11, 2006
Question
We are building 71 mahogany doors for a restoration project. Many of the doors have fixed louvers. The job requirements are that an oil finish be applied, followed by wax polishing. The contractor is not concerned about what type of oil, just that we do not use lacquer, polyurethane, or any other "modern" finish. Is there an oil product that we can spray on, then wipe on and off successfully?
Forum Responses
(Finishing Forum)
From contributor G:
There is. You can use pure tung oil - *not* tung oil finish, finish being the keyword. Most people don't know that there is a difference. I didn't for a long time. So far I have only found one good source, Woodcraft. Most products incorporate some sort of varnish or poly in it. I make my own most of the time that way. You can thin the oil, as in its pure state it is pretty thick, with spirits or paint thinner, and you can add just the smallest amount of turpentine for hand application, but not necessary for spraying.
From contributor M:
You want to be sure it says 100% tung oil. It may also say China tung oil, although the tung oil may not come from China - other countries in South America also have tung trees, and produce 100% tung oil.
From contributor T:
Tung oil is also called china wood oil. Boiled linseed oil will do the job for you too, and is usually a little less expensive. Word of caution: after you apply oil to raw wood and wipe it off, you'll find that the pores will bleed oil for several hours. If you don't go back and rewipe it every half hour or so, you'll end up with spots of cured oil on the surface that are a real pain to remove.
From contributor M:
Boiled linseed oil contains a heavy metal drier - it is not pure or food safe. If that's not important to the work, then he can also use a tung oil varnish, which is more durable than just the pure tung oil. These are "wipe on, wipe off," very thin coatings. That will fit the description you are looking for.
From the original questioner:
Thanks for the advice. I'll order some pure tung oil and get to work.
From contributor T:
Tung oil is a good oil finish, but it takes 2 or 3 days to dry between coats and it takes 5 or 6 coats with sanding between coats to get something decent. (After the first couple of coats you'll think you got some real bad advice.)
Linseed oil usually dries in a day and 3 or 4 coats with sanding between coats will give you a smoother (in my opinion nicer) finish. Boiled linseed oil used to contain lead as a dryer. It doesn't anymore. It now contains a salt of cobalt, manganese, or zinc as a dryer. Contrary to popular belief, when these finishes are cured, they are food safe. If I may quote a noted expert: "The issue of metallic dryer safety begins and ends with lead."
From contributor M:
Not to debate you, but can you show or tell me just one company that will back up that comment, that any of the boiled linseed oils with any one of the chemical driers is "food safe after it cures"? There is not one company that ever applied to the government to say its coating is food safe. That also applies to all the other coatings with solvents, catalyst, or other additives. The tung oil varnishes also dry much faster then the pure tung oils, and you are right, they do take a few coatings to look professional. They are a very easy coating to produce a traditional finish.
From the original questioner:
What about Deft Danish oil? The can says it can be sprayed.
From contributor M:
Yes, that will work.
From contributor T:
Good choice. It will produce very good results without a lot of work. It contains linseed oil and of course those metallic dryers that are bad for you. Interestingly, they suggest Deftoil for finishing butcher blocks. Do you think they would say that if they didn't believe it was safe? Watco (similar product) claims to be nontoxic after 72 hours and even my Zinsser shellac only claims to be nontoxic when dry. But contributor M is right, not even salad bowl finish claims FDA approval anymore.
From contributor M:
I should have mentioned before that extra care must be taken whenever working with oil finishes. The oily clothes that are used are known for spontaneous combustion, so be sure you keep the clothes spread out and never touching one another until they are dried, or soak them in a container of water. Be sure you read the label.
