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What Is Boiled Linseed Oil?

Boiled linseed oil is a treated form of flaxseed oil, renowned for its quick-drying properties. It's a favorite among woodworkers for protecting and sealing wood, enhancing grain appearance with a warm, glossy finish. Its versatility extends to metal preservation and paint binder uses. Intrigued by its myriad applications? Discover how boiled linseed oil can revolutionize your DIY projects.
Alex Newth
Alex Newth

Boiled linseed oil is linseed oil — which, like flax oil, comes from flax seeds, though it is treated differently and is not edible — that has been boiled until it polymerizes and oxidizes, causing it to dry quicker. When boiled linseed oil is named on an ingredients list, it may just be linseed oil, but it more often has additives including petro-chemicals and metal-based dryers to accelerate the drying process to a satisfactory level. Boiled linseed oil is sometimes heat-treated linseed oil, which dries slowly and is very thick, making it difficult to work with. The two main uses of linseed oil are as paint binders and wood finishes. While it is cheaper than similar oil products, it takes longer to dry and may not last as long.

Without any additives, boiled linseed oil is just that: linseed oil that has been boiled. This causes the linseed oil molecules to polymerize — or become a long and repeating chain — and oxidize, introducing oxygen into the oil. This makes the oil thicker, meaning it can be used for more applications, and makes it dry quicker. Regular linseed oil takes many hours to dry, making boiling is a necessity for many projects.

Linseed oil and flax seeds.
Linseed oil and flax seeds.

Most linseed oil listed in products is either loaded with additives or heat-treated rather than boiled. Additives are more common, because this makes the linseed oil more useful. By adding petro-chemicals and metal-based dryer catalysts, linseed oil will dry even quicker. This means linseed oil will dry almost as fast as other commercial finishes.

Heat-treated linseed oil is not very useful as a finish. When linseed oil is heat-treated, and not boiled, it goes through the same polymerization process, but it does not oxidize. This means the oil becomes thicker than boiled oil but will take much longer to dry.

Boiled linseed oil is often used as a paint binder for oil paints.
Boiled linseed oil is often used as a paint binder for oil paints.

Boiled linseed oil is found most often as either a paint binder or a wood finish. As a paint binder, linseed oil binds the pigment to the paint, especially in oil media. When used as a wood finish, linseed oil is able to coat and protect wood from weathering and other damage.

While this type of linseed oil is useful, it is considered lower in quality than commercial binders and finishes. The largest reason is because the drying time is much longer than other finishes, making it useless in commercial projects that require finishes to dry quickly. Linseed oil also is passed over is because it does not offer the same protection as other commercial products; it is, however, about half as expensive.

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Discussion Comments


@bluedolphin-- Have you looked online? I have a hard time finding good and affordable boiled linseed oil locally as well. There is an art store that sells little bottles of the stuff at ridiculously high prices. It's called refined linseed oil. The guy who works there told me that there is no difference between refined and boiled linseed oil, except that the latter is much cheaper! So I'm getting mine online instead.


@SteamLouis-- Raw linseed oil really takes much longer to dry than boiled linseed oil. It takes weeks for raw linseed oil to dry, at least in my experience.

The major difference between raw and boiled linseed oil is the chemicals. Boiled linseed oil has them and raw does not. As far as I know, manufacturers don't really boil linseed oil anymore. They use chemicals instead. I have looked for a boiled linseed oil without the chemicals but did not find it.

Which one you should prefer really depends on what you're using it for. I would no use boiled linseed oil for a dining table for example. But for furniture that does one does not come into contact with often, boiled linseed oil will be just fine.


If boiled linseed oil takes much longer to dry than commercial binders, does it really matter if I use boiled linseed oil rather than raw? Or should I forego both and just buy a commercial binder?

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    • Linseed oil and flax seeds.
      By: WimL
      Linseed oil and flax seeds.
    • Boiled linseed oil is often used as a paint binder for oil paints.
      By: dred2010
      Boiled linseed oil is often used as a paint binder for oil paints.
    • Boiled linseed oil is often used as a wood finish.
      By: David Antczak
      Boiled linseed oil is often used as a wood finish.