Home brewed oil finishes
One of the first finishes I ever put on a project, now over 40 years ago was a boiled linseed oil finish. It was simple and cheap and there was no way to mess it up really. It was not long though before I read somewhere that you could make an even better oil finish if you mixed it with equal parts of turpentine and spar varnish. Once I started using it I was hooked. Now over 40 years later I am still using this finish (although with some modifications) and I still think it is one of the best finishes out there. So after finishing my last project this way I thought I would write an article detailing how best to use this finish.
The finish I used on the table at the left is a modified form of the finish I used 40 years ago. Instead of equal parts Spar varnish, Turpentine, and Boiled linseed oil. I now often use a finish I call 221. In other words 2 parts Spar, 2 parts Turpentine, and 1 part Boiled linseed oil. This modification is very nice because it is very thin and penetrates very well. In addition it has proportionately more varnish in it than the even parts mixture. It seems to dry just a bit faster as well. Although, if you are in a big hurry this is really not the finish for you. You can probably put on 1 coat a day under the right conditions. And you will need a minimum of three coats. Four or five is actually a much better number. The table at the left has four coats on it for example.
Now one of the supposed downfalls of oil finishes is that they do not provide as much protection as a thicker film coating of some kind like varnish, or lacquer, or even epoxy if you really want tough. But this is the second table I have made like this. The first one is used as an everyday table for dining or playing games. Glasses of water and coffee and various dishes are set on it as you would any table and this finish is holding up very well. It is after all a spar varnish which is a very tough varnish. I have a countertop covered with spar varnish that has been holding up to extreme use for many years and is still essentially unbent.
But setting aside the practical considerations for a second the real reason I use this finish is the way it looks and feels when you are done. It is wonderful. I want people’s first impression to be, “Oh, what pretty wood” not “Oh what a shiny finish”. And this finish gives me exactly that effect. Plus I can apply this in my shop with no special precautions, no obsessing about dust or insects, I just put it on, turn off the lights, and check it out in the morning.
Applying the finish
If there is a “trick” to applying this finish it is in the surface preparation. While this is a very forgiving finish the final result will vary widely depending on the quality of the initial surface. For the table above my goal was to use no sandpaper. While I did not quite meet that goal I came really close. The main thing I used sandpaper for was to take the razor sharp edges off the legs and rails that my planes left behind. The rest was finished just as it came off the plane.
But you do want as perfect a surface as you can manage. You either want to use very sharp edge tools to get a burnished type surface or sand down to at least 400 grit, 600 really would be better. Then the fun can begin.
The first and the last coat are the most important coats. Leave plenty of time to apply the first coat. I use a cheap chip brush and soak the whole piece down and I keep it wet for as long as I can stand it, or until is starts to drag on my brush. This is important because for this to be a tough finish it needs to penetrate as deeply as possible. When you feel that you have let it soak long enough. Wipe it down with a paper towel. Don’t worry about getting every last bit of surface oil off, not yet at least. Once you have wiped the excess off let is stand for 30 minutes or even an hour or two. Then with a clean paper towel or a cloth wipe it down hard and get all the excess off. Now let it dry for AT LEAST 24 hours. 48 hours is usually better. I usually do this at night and then I check on it again in the morning and if there are any sticky spots I rub those down with a clean cloth before they fully dry. This is an important step and I do this 8 – 12 hour rub-down between every coat. That may seem like a lot of work but actually it is not. I tend to finish at night and rub down in the morning before I do anything else. The beauty of this finish is that I can let a coat of finish dry while I work in the shop. The dust will not hurt it at this point.
After the first coat is dry and ideally pretty hard (this may take longer than 24 hours) it is time to feel the finish. If it is smooth great you can move on, if not don’t sweat it. Take some very fine sandpaper and rub it down. Then give it another coat just like the first, only you do not have to let it soak as long. The thing I like to do on subsequent coats is to apply the finish with 0000 steel wool, and rub it in briskly. This to my taste gives the best finish whether I am using 221 or even if I am using just plain old Boiled Linseed Oil. Rub it in with the steel wool hard and wipe off the excess with a paper towel, wait a while, then rub it down dry. Wait overnight and buff it out in the morning.
Do this as often as required, but do not let the finish build up on the surface. You will know if you do because it will show as an obvious and really pretty awful glossy film. If you find that you have some patches like that don’t panic, this is why I love this finish it is fixable. You either rub it down hard with a cloth until the horrible gloss disappears or, if that does not get it, go back to 0000 steel wool dipped in finish and rub it out, then make sure you get all the excess wiped off this time.
The Final Coat
The final coat goes on like all the rest. The difference is not how it goes on but how and when you rub it down. For the last coat the morning after rub down is very important. I say the morning after because with the brand of varnish I am using that is about the right amount of time. What you want is to let the finish dry but do not let it get hard. Dry but not hard is usually about 8 – 12 hours later for the stuff I am using. Your time may vary, once you know how a particular brand behaves you will probably want to stay with that brand to avoid future surprises.
When you do the final rub down your cloth should start to drag just a little bit as you rub it down. Ideally it will drag enough to generate heat but not so much that it is a miserable job. This drag is important do not flip your towel let it build up heat. Put as much pressure on it as you can and let it generate some real heat, this will set the finish and bring it to a nice warm shine that shines, but is not glossy. Once you are satisfied with the shean and the surface you are done. Let it stand in a warm room for at least two full days before using it in anyway. It takes a long time for spar varnish to really get hard even in it’s unmixed state. Mixed like this it actually takes a fair bit longer. As I said earlier if you are in a big hurry this is not your finish, but if you have the time I think you will find that this finish will really reward your effort. And you can apply it while working on other things in your shop. Try that with a regular film finish sometime, you will see why I love this finish.