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The Process of Alkali Refining Linseed Oil

12 thoughts on “The Process of Alkali Refining Linseed Oil”

  1. I never knew the process was so complex and had so many steps,

    What’s involved to produce Cold Pressed Linseed oil?


    • Hello Mark,
      We learn a lot from researching these articles too, including how complicated industrial processes can be! Another interesting point that wasn’t mentioned in the article, is that the artist materials industry uses only a small fraction of the oils produced for food, the coatings industry or for other industrial uses.

      Regarding cold pressed oil, it also goes through a number of steps without the use of chemicals or heat. The seeds and oil must be kept below around 100 degrees F in order to be classified as cold pressed. The seed is pressed without steam which produces less oil with less impurities. Because pressure creates heat, the presses can be cooled. The oil is captured under a blanket of nitrogen to keep the oil fresh and so it does not oxidize. The oil can be washed with water and/or clay, filtered and centrifuged. They might also winterize the oil, which cools it to the point when the waxes in the oil solidify and drop out.

  2. I agree that you have broken down a very complex process so a non chemist can understand. It really made me understand the difference between this product and cold pressed oil and the advantages in preparing paint and using as an additive. Thank you. I am sharing this with my students. Bravo

    • Hello Kristine,
      Thank you for your comment and for sharing this article with your students! We are glad you found it helpful!
      Best Wishes,

  3. Linseed oil has been recommended to stabilize plywood woodblocks for Japanese style carving and printing. One source mentions “activated linseed oil.” Is that simply boiled linseed oil? Further can you comment on drying times? One source says it takes several days and another says about a single day. Thanks very much.

  4. Hello Jawed,
    Unfortunately, we do not have specific information about different presses and the pressure or temperature they produce. There are standard requirements for keeping the seed under a certain temperature (~100F) in order to label the oil product “cold pressed”, but for heat and steam pressing, the heat and pressure used to extract the oil seem to be determined by the type of press and the desired end use for the extracted oil. Perhaps you can contact a seed press manufacturer an inquire about the specs of their machines.
    We wish you the best in your research.

    • Hello Sir,
      We are not sure if these terms can be used interchangeably. It appears break-free oil has been cleaned to some extent, perhaps with an acidic solution only. This is to remove the “break” or gums, also called mucilage, from the oil. Removing these impurities allows the oil to be heated without “breaking” or becoming cloudy and clotted. Oils that are heated in this way are typically used for varnishes. Alkali refined linseed oil has likely been through a more vigorous cleaning process than break-free oil.
      We hope this helps.
      Greg Watson

  5. Hi we are a paint manufacturing company & for testing of incoming pigments & extenders we need acid refined linseed oil with an acid value of 5-7 mg KOH/gm of sample. This test is as per ISO 787 specification. Can you please suggest?

    • Hello John,
      There are a number of larger linseed oil manufacturers who provide oils with varying acid values. We do not disclose our manufacturer, but quick internet search should turn up several results.
      Take care,


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