The linseed oil that we use is only extracted by cold pressing. This method of pressing the oil from linseed without prior heating gives a small exchange but in return a cleaner and clearer product.
The newly pressed linseed oil is called cold-pressed raw linseed oil and stored for at least half a year prior to being used. During storage, the impurities fall to the bottom and the clear pure oil is drawn off and ready for use. As its surface tension is lower than water, the raw oil has an unequalled property to penetrate into the substrate. No prior heating of the oil is necessary for this penetration process to take place. This property makes it suitable for use for primer paint applications outdoors. We also use this oil in the manufacture of our artist’s oil paints. Raw linseed oil dries relatively slowly. Very early on it was discovered that heating the oil improved its drying properties. This process is generally referred to as “boiling” and the product is retailed under the name coldpressed boiled linseed oil. In the boiling process we use, the oil is heated to approx. 140° C and both oxygen and metal salts are added to make the product more reactive.
The oil is slightly thicker than the raw product but has the same excellent adhesion and penetration characteristics. This oil is used as a binding agent in our paints. We also refine raw linseed oil by using a very old method that consists of subjecting the oil to natural sunlight and oxygen outdoors for several months. During this process, the oil oxidizes and thickens and is also bleached by the sunlight. The oil is called sun-thickened linseed oil and used an additive to paint in the final coat in order to improve the gloss, covering and drying properties.