Long-Oil Varnish is The Oil Finish you Wish Oil Was

When I started making varnish, I made a recipe that was supposedly for violins. I think it’s as bad or worse than plain rosin and linseed varnish. Oil varnishes are for the most part some part resin, some part oil and then a solvent both to stop the varnish from bricking itself quickly, and to make it usable or brushable, or sprayable.

But after that, I tried a few things to make rosin and linseed varnishes quickly and attempt to get some hardness. My kind of favorite varnish so far is 1 to 1 types, or one resin and one oil, and I usually store them with one part turpentine. They’re too thick to use at that if they have one of the harder resins, but store well. Drier comes in later.

Even if rosin varnish can be made a little harder by adding lime, which dissolves in the varnish, it turns out that it’s still not very good, and it can’t tolerate water. Varnish with good adhesion doesn’t seem to lay out like lacquer and you have to degloss the surface to apply more. if not, it literally pools in some areas and “pulls itself toward itself” leaving bare areas. It’s really bizarre. it’s easier to do this sanding neatly if you can use a little bit of water – this deglossing. At least it is to me because it’s easy to wipe off anything that stays around. Varnish finds anything unusual on a surface and then builds around it, so little missed dots of trash are a problem.

Except rosin and linseed won’t really tolerate varnish and the surface gets squishy.

Steve V. pointed me to a book by Ralph Huff, which is as far as natural resin based varnishes go, pretty modern. Pre-WWII, but not by much. Huff predictably says rosin and linseed isn’t worth giving recipes for after describing it. As time goes on, I agree, and older texts were hit or miss. There are things you can do with rosin to improve it, but they are not something anyone reading this will ever do and unless you’re imitating violinmakers or trying to on a $25k violin, I personally wouldn’t bother with them either. There are other resins that are as good as modifying rosin to a darker longer form would be, and they are usable after a couple of hours of running (cooking out impurities at a very high temperature).

But Huff in the book then quickly goes on to describe the usefulness of tung oil. Most people reading this know tung as the very expensive polymerized oil that comes in a solvent. It’s probably $50 or more per pint after the solvent evaporates – that is for a pint of actual oil. Why that stuff is so popular is a bit of a mystery to me, other than it’s easy to use, i guess, and it dries a little faster than raw tung. But raw tung from a bulk supplier like Jedwards is high quality and literally about $34 a gallon with no solvent. So if you’re going to make basic varnishes, there’s a lot of substance to it. And getting away from what I see in the finish industry as taking stuff that doesn’t cost that much and putting it in little cans and making it cost a lot.

Raw tung will dry reasonably hard and it can also be heated or thinned to penetrate. if you want it to dry faster, and it will dry nearly clear compared to the cloudy polymerized stuff, 1 percent klean strip japan dryer will do the trick. I’ve learned to wash it with hot ethanol, too, and get rid of kind of the stinky nutty smell that’s in it.

But it is an in the wood finsih, a very good one, but that looks a little dull, and if you dare allow a little bit of the fairly hard but rubbery finish to dry on top of wood, good luck getting something that looks suitable.

Transforming the Linseed oil Varnish

By the way, before I start – I made some odies like stuff with wax in the actual oil with drying agents. I think putting wax in a finish is stupid – just my opinion. Wax is a short molecule and maybe there’s some magic that makes it still feel waxy and bond in a finish, but I think if that were actually the case, the hardwax oils would be fully waterproof. And they’re not. tung oil with a little wax in it works like shit – it spots with water if you allow the water to lay on it and then you have an ugly look. It feels just grand when you apply it because of that, and I know people like the dull look but I don’t. So that option to use tung another way is out in my book.

Tung itself will form a hard layer in wood, and so will linseed oil, but tung is more waterproof than linseed. it’s still missing the ability to go in the wood and make a nice finish on the surface.

Enter the 1 to 1 linseed rosin varnish that I have, really waiting until I just give up and burn it.

As I was at the beach reading, I noticed Huff provided a recipe that’s roughly 1 part limed rosin varnish, 1 part linseed oil and 2 or a little more parts tung oil. He also mentions an industry trick back then to cover up the use of mineral spirits, which are much cheaper than turpentine – and that is to use a very strong solvent that’s in the class of limonene as a fraction of the solvent and the rest mineral oil, so it seemed like two things to try. Oh, and the comment that clued me in was Huff saying that this recipe made a durable varnish for outdoor use, or something along those lines. All Tung is even better, but part linseed oil would definitely be easier for a new cooker because of how reactive Tung is.

I got back from the beach, busted out my junk rosin and linseed varnish, cooked the solvent of (which wasn’t trivial) and then added tung slightly greater than two times the original linseed. The result is a finish that has some characteristics of varnish, but isn’t nearly as sticky as a very good varnish is, it levels out easier, and it has great clarity.

This is that long oil varnish on satinwood, which is an interesting wood. The depth isn’t quite what a 1 to 1 high end varnish looks like, but most people reading have never actually seen that in person. This inexpensive and fair to say, not the hardest varnish in the world, but very tough when it dries, has better color and clarity than any polyurethane I’ve ever seen, and it lays out nicely. Pouring water on the surface and letting it evaporate leaves no evidence.

You can wipe it, brush it, and I’m sure if you wanted to thin it a little more, spray it.

I added 1% japan dryer by solids volume, which allows brushing a healthy dose once a day, or easily wiping two coats a day. If you’re uber something or other about driers, since a good choice for varnishes has cobalt (which helps prevent skinning, or put differently, helps to have the layer dry evenly and avoid cracks and crows feet), then you can apply thin layers and find the sun and you’ll have a touchable surface in a couple of hours.

This isn’t a hard varnish to cook, though it’s not really wise to make the rosin/linseed varnish first and then cook off the solvent – cooking the solvent out to get enough out for the Tung and prior varnish to crosslink isn’t as trivial as just cooking off some of the solvent. As you get less solvent, the temperature needed to cook more off goes up and you soon get kind of pinched into a place where the varnish could turn into a ruined pot full of gel. Fortunately, I didn’t get there.

I’ve already made similar but limed rosin and all tung varnishes 1 to 1 and not long oil, and they are almost shockingly good as a furniture finish. But a little bit more difficult to apply.

There’s a short clip showing the liveliness of the surface. when the rubber hits the road on the cost of this, it’s not more than any decent consumer clear finish. of course, you do have to cook it, but if it ends up being around $50 a gallon to cook, I can’t think of anything for $50 a gallon that comes close.

In the video, notice the kind of sheen the wood has. it looks a little bit three dimensional in person and remains a full colored look from across a room in raking light rather than looking like a dull surface. I sure hope this look comes back in style at some point. Not that it’ll affect what I make or the finishes I use.

Every little extra new thing with varnish or spirit types (french polish) just narrows the already narrow chance I’ll buy any finish in the future that’s commercially made. Now this provides a pretty easy to use option that will wipe like an oil, and if thinned, it will penetrate like one, but also show good clarity on a surface if it’s built. I have nothing wood outside at this point other than tung oiled garden wood with green pigment in it. Pigment in the finish is a whole other ball of wax, but the point of mentioning that is unfortunately, I have no real object outside to test how this stuff holds up in the sun. The sun kills anything that it can get to over time. Pigment is one way to limit how far in it goes.

I know for sure that helsman urethane that I’ve used in the past on south facing railings isn’t really suitable. It’s a just passable consumer finish, and it’s cheap if you compare it to a real varnish like epifanes. But I wouldn’t be surprised if this would outlast it in the sun. helmsman always got brittle and cracked at joints pretty quickly for me. That was the undoing of my wooden rails – sound wood showing, and rotted joints hidden inside.