Wood is an extraordinary building material that can last hundreds of years, especially old-growth wood, when given a little care. Just like any material, when exposed to the elements, it can slowly degrade. But, you can bring old wood back to life by using boiled linseed oil and prepare it for a few more decades of service life.
Don’t let grey, weathered wood convince you to replace it when all it needs is a little TLC. Other than rot or physical damage, boiled linseed oil is a great treatment for old dried out wood. It also makes a fantastic pre-treatment before painting to extend the life of your paint job.
What Is Boiled Linseed Oil?
No, it’s not actually linseed oil that has been boiled. Linseed oil, also known as flaxseed oil, is a colorless to yellowish oil obtained from the dried, ripened seeds of the flax plant. The oil is obtained by pressing the seeds to withdraw the oil. Linseed oil is a very slow drying oil, and so to make it more readily useable, some guys in lab coats mixed a combination of raw linseed oil, stand oil (linseed oil that has been heated to near 300 °C for a few days in the complete absence of air), and metallic dryers to create a product that behaves much the same way, but dries before the cows come home.
How To Revive Old Wood
UV rays break down the fibers in wood, and after enough exposure, wood begins to turn grey from the sun’s effects. Paint and other coatings won’t adhere well to this grey wood, so it’s important to treat the wood before trying to paint again. Follow these few simple steps to revive that old wood and get it ready for some fresh paint or varnish.
1. Sand Lightly
Using something like 120-grit sandpaper make sure there isn’t any dirt or loose wood fibers lingering. Sanding also helps open up the pores of the wood to prepare it for the oil. Wipe off the dust, and you’re ready for oil.
2. Apply Oil
Mix up a 50/50 solution of boiled linseed oil and turpentine. Liberally apply the mixture to the wood using a cotton rag. You can brush it on if you’d like as well, but I prefer a rag. Make sure you apply a good amount to the surface, not just a light coat. The oil will penetrate the wood and soak in quickly. If the surface is still shiny after a couple minutes, wipe off the excess and set your rag out to dry.
Read this post about how to safely deal with rags soaked in boiled linseed oil because if not handled properly, they can spontaneously combust!
Let the oil dry for at least 24 hrs, but 48 hrs is even better. Don’t put a second coat on because with extra coats, the oil can build up on the surface and create adhesion problems with your paint. One coat is more than sufficient.
3. Prime & Paint
Using a good oil-based primer, cover the bare wood after the oil is cured. Using an oil-based primer rather than a latex primer helps create a bond between the boiled linseed oil and oil primer, which gives your paint job an extraordinary bond. Latex primers are water based and don’t work as well with this system. You can finish with a latex finish paint on top of the oil-based primer, but stay away from a latex primer in this situation.
Boiled Linseed Oil as a Finish
Not just a pre-treatment, boiled linseed oil works great as a wood finish itself. It won’t give you a super hard and durable finish like polyurethane or varnish, but with enough coats, boiled linseed oil will eventually build up a beautiful and protective finish. I’ve used it for years, as well as my own custom blends to finish furniture and table tops with great results.
Boiled linseed oil gives a very “close to the wood” finish where you can really feel the wood instead of layers of plastic poly on top. The trick is to add multiple coats over the course of a week or so. Usually giving it about 24 hrs between coats, you’ll build up between 3 and 6 coats of oil depending on how thirsty the wood is.
Boiled linseed oil really brings out the deep rich color of the wood and accentuates the grain. Even less attractive woods look pretty decent after being oiled. Finish the project with a coat of wax for even more protection and you’ll have professional looking results.
Here’s some projects I’ve finished with Boiled linseed oil below.