Raw vs Boiled Linseed Oil. A Clear Explanation

Linseed oil is a popular oil for finishing wood among woodworkers. But if you will search to buy this wood finishing oil, you will be given the choice between raw vs boiled linseed oil vs polymerized linseed oil. You have to understand that although it is all linseed oil, there is an important difference.

Raw linseed oil is food safe, but the major drawback is the long drying time. Boiled linseed oil dries faster, but contains toxic substances, making it not food safe. Polymerized linseed oil is raw oil that is heated, which changes the viscosity and drying time, and is still food safe.

In this article, I’ll take a closer look at the essential differences between raw vs boiled linseed oil vs polymerized linseed oil so that you know exactly what you need for your project in just a few moments. Read all the details carefully, and don’t just use any linseed oil, because, the wrong choice can have serious consequences.

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What Is Linseed Oil?

Linseed oil is extracted by pressing dried flax seeds. Flax oil is another name for it. The oil is extracted using solvents or under pressure after the flax seed has matured and dried.

People use this oil for medicine and cooking in addition to protecting wood products. As a result, when looking for non-toxic oils for treating wood that comes into contact with food, this oil is a good choice. Linseed oil is also mentioned in my articles How To Make Wood Waterproof Naturally (4 Simple Options) and What Is The Best Food Safe Wood Finish (All In One Guide)

The reason linseed oil is popular used to protect wood products is that it is a drying oil. This means that the oil penetrate into the wood and polymerizes into a solid form after application.

Raw Vs Boiled Linseed Oil

Linseed oil comes in several forms. The best known are raw linseed oil and boiled linseed oil. Later in this article, I will come back to a third form that you should definitely see. But first I’ll start by showing you the differences between raw vs boiled linseed oil.

What Is Raw Linseed Oil?

I’ll start with raw linseed oil because it’s the purest form of linseed oil on this list. This is the type of oil obtained directly after pressing the linseed. This type of linseed oil is the kind used as medicine and for cooking, which I talked about earlier at the beginning of the article.

Is Raw Linseed Oil Food Safe

Yes, raw linseed oil is perfectly food safe. Better yet, it’s even healthy to consume flaxseed oil from time to time. For that reason, linseed oil is also often used in food supplements.

So you can safely treat your cutting boards or other wooden kitchen utensils with linseed oil without having to worry about chronic toxicity as with some other wood finishers.

What Is Raw Linseed Oil Used for

Raw linseed oil is a great finish for wood products. It even has a waterproof effect. To work properly, linseed oil is best applied in thin layers and allowed enough time to harden. But be aware that this curing does take some time. It may take 2-10 weeks to completely dry, depending on the environment and the thickness of the layers you applied.

What Is Boiled Linseed Oil

The difference between raw vs boiled linseed oil is that with boiled linseed oil, petroleum-based desiccants or heavy metals have been added.

Some of the petroleum-based compounds added to linseed oil serve to shorten the long drying time of crude linseed oil. The most well-known products that are added are naphtha, mineral spirits, and di propylene glycol monomethyl. Cobalt and manganese are the most common metals found in boiled linseed oil.

Is Boiled Linseed Oil Actually Boiled?

Although the name would suggest that this type of linseed oil is boiled, the answer to this question is: No, it is not boiled at all. It’s just a name given to it because chemicals are added to it to shorten the time it takes for the oil to dry.

Is Boiled Linseed Oil Food Safe

Because of the drying compounds added to boiled linseed oil, it is not food-safe at all. Boiled linseed oil often contains a chemical known to cause cancer and birth defects or other reproductive harm.

What Is Boiled Linseed Oil Used for

Boiled linseed oil is often used on wooden furniture where food safety is not an issue, but the speed of drying takes precedence.
With this type of oil, you can easily apply two or three layers within the same day. This is of course dependent on the weather.

Avoid using it on wooden products that come into contact with food. Because of the added chemicals, you can trigger chronic diseases and cancer.

a Third Option: Polymerized Linseed Oil

In addition to raw and cooked linseed oil, there is also polymerized linseed oil. In this section, I’ll go over the differences between raw vs boiled linseed oil vs polymerized linseed oil more in detail.

What Is Polymerized Linseed Oil

Polymerized linseed oil is created by slowly heating raw linseed oil in the absence of oxygen to around 300 °C (572 °F) over a few days. A polymerization reaction occurs during this process, increasing the viscosity of the oil and shortening the drying time.

So boiled linseed oil is not boiled, while polymerized linseed oil do is boiled. I hope you don’t go cross-eyed, LOL.
Another name for polymerized linseed oil is danish oil.

Is Polymerized Linseed Oil Food Safe

Because no chemical products are added to polymerized linseed oil, this type of oil is 100% food safe. Heating changes the viscosity and shortens the drying time, but the composition of the oil does not change, and it is just as safe to use as raw linseed oil.

What Is Polymerized Linseed Oil Used For

Polymerized linseed oil is becoming more popular as an alternative to raw linseed oil. It has the same food-safe properties as regular paper, but dries much faster. So, if you want to treat a wooden item in a food-safe manner but don’t have the time to wait for the linseed oil to harden sufficiently, this is the oil to use.