Our Linseed Oil
From Farm to finish
Starting with a high quality artist grade oil is the most important part of our paint making process, but to get there, we have to make our own. We wouldn’t have it any other way.
At Heron, we approach oil refining as artists. With years of cleaning our own oil for personal use in paintings, or making varnishes, we know the value of a hand-refined oil. Changing the rheology and working properties of linseed oil is an art all on its own. There are many ways to manipulate linseed oil, and we’ve found what works best for us. There’s simply nothing like Heron Linseed Oil.
We begin with cold-pressed brown linseed oil grown on family farms in the U.S. Some may know this raw, unrefined oil as food-grade flax oil, a dietary supplement. To prevent impurities from getting into the oil, the flax seeds are cold-pressed instead of undergoing a chemical extraction technique.
The oil is stored for several months to allow settling and clearing. Next, it is washed many times with several different natural techniques to purify it of the non-drying components like waxes, vitamin E, and phosphorus containing compounds. We want oxidation and polymerization in our oil so the many antioxidants and non-polymerizing compounds are removed. (While these non-drying components are great for human consumption, they are detrimental to a good surface coating.) This refining (degumming) method is done to make an oil that cures faster, stronger, and yellows as little as possible.
We then heat the oil for several days which slightly thickens the oil through pre-polymerization. This heat bodied oil is fantastic for grinding pigments into the oil, coating every particle. It also aids in flow and leveling in the finished film.
The refined oil is then used as the binding agent in our paint. Starting with a clean, fast drying oil allows us to use extremely small amounts of manganese drier in our paints to make them more reactive. These driers help our paint cure in a reasonable time for climates that are prone to more humidity or in cooler weather painting.
Our paints are available without the manganese drier upon request.
WHY WE REFINE
Why not use raw, cold-pressed flax oil and avoid this laborious process? Straight from the press, raw oil is full of mucilage and phospholipids. It may be fine as an edible oil, but it's incredibly slow to dry, can yellow significantly, go rancid and is more prone to mold attacks. Roughly 8% of raw oil is free fatty acids and these lead to a weaker dry film matrix. In order to make the dry times reasonable, large quantities of metallic driers are needed for raw oil applications. Oils that contain more driers can impart brittleness to the film and wrinkling of the surface. Large amounts of biocides or solvents (chemicals that are against our mission at Heron) would be needed to make this type of oil adequate for exterior work.
We refuse to use commercially available alkali refined oil or RBD oils (refined, bleached, deodorized), as well. Those oils are stripped of components we actually want, including the fatty acids that cause oxidation in order to increase their shelf life. Because of this, RBD oils are slow drying, lifeless and grind into pigments terribly. These alkali refined oils create a paint that’s slick and thin under the brush, but it won’t cling and “bite” the surface (something we really want if we’re applying thin coats). The finish from these sub-par oils has less sheen, weatherability, and elasticity. They’re no good.
We could buy refined linseed oil with some (not all) of the properties we’re looking for, but it would be from large corporations. We wouldn’t know the farms and families growing the flax or if it's grown in the U.S. Using U.S. grown flax from small farms is important to us.
These extra steps are time consuming and expensive, but we feel they create the type of oil binder best suited for our handmade paint. We’re able to create an easily brushable, adhesive, fast drying, flexible and weatherable finish.