Selder Grundolja Purified Linseed Primer Oil Woodworking Finish

Selder Grundolja is a pure, natural linseed oil made in Sweden. 

Linseed oil has always been a traditional workshop staple. However, the oil you can buy from the big-box hardware store is either full of toxic chemicals, or it takes weeks to dry, and goes yellow over time.

Selder Grundolja is different. It is a pure, natural linseed oil from which the non-drying constituents have been removed by a unique refining method.

‘Grundolja’ means ‘primer oil’. It is specially formulated to preserve and protect timber, making wood rot-resistant by making it water-repellent – rot fungi cannot grow in dry wood. Furthermore, no organism can extract nutrients from the oil itself.

Field tests and tests in rotting chambers show that Selder Grundolja protects wood in soil against rotting for at least 24 years. 

Grundolja is easy to use. At 20°C and with good ventilation, Selder Grundolja dries within a day.

Click here to download the product user manual.

Why Use Purified Linseed Oil? 

Linseed oil is a drying oil. It contains short molecules that link together when exposed to oxygen, forming long molecules. This polymerisation reaction turns the oil from a liquid to a solid – very handy for wood finishing!

However, non-purified linseed oil contains a lot of other organic substances besides the oil itself: for example, proteins, waxes, and antioxidants. These are all essential for the seed to germinate, but they cause problems when we try to use non-purified linseed oil as a finish. They slow down the drying of the oil, cause it to yellow over time, and provide a food source for harmful fungi and bacteria. 

‘Boiled linseed oil’ is a slight improvement, but it uses toxic metallic dryers to catalyse the drying reaction, like cobalt and manganese. These additives do force the oil to polymerise, but do not stop it from yellowing or degrading over time, since the proteins, waxes, and antioxidants are still present in the finish.

Selder’s unique process removes the problematic organic substances from the oil without adding anything extra, leaving a pure oil that dries fast, is non-yellowing, and incredibly durable. 

Who is Selder?

Selder & Company is a family business based in Sweden with over 40 years of experience in linseed oil. In the early 1980s, Mikkel Selder was working on restoring traditional wooden houses. His dissatisfaction with commercial linseed oils led him to start researching and developing a unique purification process to produce an oil without toxic additives that delivers a superior result on all timbers.