107 – Oil-Based Finish Basics
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Oil-based finishes are typically the first type of finish we confront as woodworkers, be it straight oil or a can polyurethane. Although they are all derived from oil, these finishes can vary widely in terms of application method, durability, and maintenance. The key to understanding these finishes is to understand their ingredients. With that foundation in your tool belt, you can start looking at ingredients lists instead of brand names and labels, and you’ll know exactly what to expect from the finish. Since this is a live session, we have a bunch of viewer questions in the video as well.
Topics include:
- What is oil?
- What is varnish?
- What is the relationship between varnish and polyurethane?
- The relative durability of oils, varnishes, and oil/varnish blends.
- How to see past marketing jargon.
- Why I like Arm-R-Seal.
Products discussed in the video:
Occasional Table- Project of the Week
This week’s project comes from Jason (aka cfiiman in the chatroom). He writes:
It is made out of solid black walnut and a curly maple decorative border…I went with dovetails on the rails and for my first time I think they turned out ok, the table is finished with tung oil…I am in the middle of a “matching” table, sort of, but I am going with finger joints instead of dovetails b/c I really think they look good and mortise & tenon rack in the bottom. Thanks guys!
It’s a very unique piece that includes some unconventional features. I for one would like to know more the joinery used for the brace at the bottom. Nice work Jason!
Home Brew Finish Mix- Question of the Week
This week’s question comes from Brian. He writes:
I recently watched a woodworking show on TV. The cabinet maker used a mixture of linseed oil, tung oil, and polyurethane for the finish. He stated that he bought it off of the shelf. I can’t seem to find anything like it on the internet. Do you know of any product like this, or do I have to mix it myself? If I have to mix it, what is the ratio?
And here was my reply:
“Hey Brian. If you mix it yourself, the standard mix is approximately 1/3 each. But that’s a mix that has some redundancy built in. You would probably be better off (unless you strictly want an oil finish) with a mix that contained 1/3 (linseed oil OR tung oil), 1/3 polyurethane or other varnish, and 1/3 mineral spirits. This will give you a very durable wipe-on finish with the added benefit of varnish. There are numerous oil/varnish blends that will be similar to the above mixture. Waterlox, General Finishes Seal-a-Cell, and Watco Danish Oil, just to name a few common ones.”
Natural Looking Bartop Finish? – Viewer Question
This week’s question comes from Doug. He writes:
“I am building a bar top from 8/4 Walnut for my son’s new home, and he wants to have a very natural finish on it – no film finish allowed. My first thought was to use BLO, but some research has led me to think that Pure Tung Oil might provide better protection. Is Pure Tung Oil a better option than BLO for an open grained wood like Walnut?”
And here was my reply:
Hello Doug Sounds like one beautiful bartop!! When it comes to protection, BLO and pure tung oil are pretty similar. One thing they have in common is that neither one offers a great deal of protection. If you had to choose, I would say to go for the BLO, since the pure tung oil will take longer to cure. BLO does have a tendency to “yellow” a wood over time, but that is a non-issue with walnut.
Now obviously your son is the boss here. But indulge me while I make a small suggestion. I can totally understand why he doesn’t want a film finish. I can’t stand the way they layer those thick finishes on bar tops. They should have just used something made of plastic, instead of wood. But there is a compromise between the plastic look, and the natural (unprotected) look. Just to clarify, BLO will certainly be better than nothing at all. But for a bartop, your son might regret this decision after the first few spills.
So my suggestion would be to try to achieve the best of both worlds. Give the bar top a very natural-looking finish, while imparting a great deal more protection than an oil alone. There are a few products on the market today that contain oil and varnish together, like Watco Danish Oil. Because there is so much oil in the mix, you would have to put on about 5 or 6 coats before you really start to get an appreciable film. But applying 2-3 coats will give you a really nice and natural look, while protecting the surface with a little varnish at the same time. And if you go with matte or satin formulas, I think your son will be even happier with the results. The great part about it is, you can look at the surface after each coat and determine whether or not you want to add another. Dilute the mix with mineral spirits if you want even more control. And also keep in mind you can simply make your own oil/varnish blend by mixing 1/3 mineral spirits, 1/3 BLO, and 1/3 polyurethane.
Either way, make sure you sand lightly between coats to keep the finish nice and smooth. After the final coat, either sand with 1200 grit paper or buff with 0000 steel wool. The wood will not only look natural, but will easily repel the occasional spill.
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