Primer Oil

Drying oils that make wood resistant to water, rot and increases its bending strength.

Available in 5 litre and 1 litre containers. Retailers

PRIMER OIL is extracted from linseed oil using our unique refining process. It consists of 100% unsaturated (i.e., drying) linseed-oil fatty acids made non-biodegradable by pre-polymerisation, giving the oil the desired viscosity and drying time. PRIMER OIL dries into the polymer linoxyn (which permanently attaches to wood and resists microbes, insects, fats, petroleum products, salts and household acids, e.g. lemon, wine and vinegar). At 20°C / 60°F and with good ventilation, PRIMER OIL dries in 24 hours or less. Read more on this here: TECHNOLOGY.

PRIMER OIL makes wood rot-resistant by making it waterproof - fungi cannot grow in/on dry wood, and no organism can extract nourishment from the oil.

Field tests and rotting chamber tests show that PRIMER OIL protects in-soil wood against rot for a minimum of 24 years.

The dimensional stability and the increased bending strength (doubled in our experiments) is a result of the wood merging into a natural composite with linoxyn.

Sunlight will fade the surface to a shade of grey. The colour is easily revived by rubbing a small amount of PRIMER OIL on the surface.

PRIMER OIL-treated wood can be glued, polished with LINSEED VARNISH OIL or painted. For optimal results, paint with Selder & Co’s linseed oil paints.

Download the Product Data Sheet (.PDF format) here: PRIMER OIL

Video: Skoghults Snickeri joinery applying hot refined linseed oil

Video: Carpenter Martin Lydén deep-impregnating wood in a deep-frier


Wood can be protected using PRIMER OIL in multiple ways. The simpler ways give basic surface protection, whereas more complex methods give deeper oil penetration. Using an autoclave, even the heartwood of whitewood of thick dimensions can be impregnated.

Note that birch and beech becomes mottled when oiled and thus a good oiled surface is difficult to achieve. This is because these woods absorb lots of oil, and the colour of the wood varies, particularly on different grains of lamellas.

Treatment with oil at room temperature

Liberally apply PRIMER OIL to dry wood with a brush. Spread oil from saturated areas to areas that still absorb. The oil penetrates a few tenths of a millimetre (roughly 1-5/250 of 1”) in healthy wood. This seals porous-surface pores and is used before painting with Selder & Co's linseed-oil paints. Note that cracked and damaged wood (particularly pressure-impregnated wood) deep-absorbs oil at room temperature. More on this below.

Impregnation with a brush

Use a deep fryer to heat PRIMER OIL to 130°C / 266°F. Apply and spread as above using a natural-bristle brush - synthetic brushes melt at these temperatures. Use our thicker LINSEED VARNISH OIL for pressure-impregnated wood. The impregnation method achieves 1-1.5 mm penetration (roughly 1-2/250 of 1”). By heating the surface with a heat gun or IR heater while working, you can achieve penetration of 2-3 mm (roughly 2-3/250 of 1”).

When treating wood at 130°C / 266°F with PRIMER OIL, moisture in the wood evaporates, bordered pits open outwards due to the vapour pressure in the cells, and the warm, low-viscosity PRIMER OIL penetrates. You can see small steam bubbles on the surface when you apply warm PRIMER OIL.

You can safely work with 130°C / 266°F PRIMER OIL - it will neither burn nor fume. It’s poorly heat-conducting, so you can dip your fingertips in it or wipe your brush against your hand with no risk of burns. Its boiling point is 300°C / 572°F, and it will start to exude a white, sharply smelling steam from its surface at 180°C / 356°F. At 130°C / 266°F, it will only produce a faint smell of linseed oil.

Excess oil left on the surface will leave a sticky skin. To avoid this, remove excess oil after 20-30 minutes (oil applied at room temperature after 1-2 hours). To remove a sticky skin, use a card scraper and then polish with oil.

Deep impregnate end wood: Heat PRIMER OIL to 130°C in a fryer. Place the workpieces in the warm oil and leave them there until the bubbling of escaping steam has stopped. Turn off the heat and let them stand in the oil for another 15 minutes. Lift them up and let them cool. Oil that remains on the surface forms a sticky skin. To avoid this, after 20-30 minutes, carefully remove any oil that may have remained on the surface. If you want to remove such skin, gently scrape it off with a sickle and polish with oil. Video of the carpenter Martin Lydén deep-impregnates end wood in a pot at the building site.

Give time to oxidize: the oil dries by oxidation and the time needed to dry depends on two factors: the supply of oxygen and the temperature. The oil can be dry to the touch in a few hours’ time on a windy, hot summer day, whereas it can take up to a week in a cool, poorly ventilated garage.

Wash brushes, tools and containers used with a strong soft soap, e.g. STRONG SOFT SOAP.

Gluing or painting

You can glue and paint wood impregnated with PRIMER OIL, preferably with Selder & Co's linseed oil paints, which attach permanently and can be easily maintained by applying a small amount of LINSEED OIL VARNISH when the colour starts to fade after one or more decades (depending on the amount of UV exposure).


Cloths and other porous materials moistened with linseed oil must be soaked in water without delay. Oil-treated surfaces do not ignite on their own. The danger concerns only fibrous materials.


No respiratory protection necessary. Provide good ventilation. The oil is a poor heat conductor and does not cause burns if spilled, but be aware that metal objects that have been in warm oil burns.


Sunlight will fade the surface to a greyish colour. Restore the original colour by rubbing in a small amount of PRIMER OIL. Warning: do NOT clean the surface with alkaline detergents (like STRONG SOFT SOAP), as the oil reacts with alkali, causing the outer layer to dissolve. If this occurs, rub in a small amount of PRIMER OIL to restore it - or you could paint that surface.


When you immerse, i.e., “deep-fry”, wood in PRIMER OIL at 130°C / 266°F and continuously provide enough heat, the moisture in the wood obviously boils out much more efficiently than when just applying warm PRIMER OIL with a brush.

When the temperature is lowered to 90°C / 194°F, a vacuum occurs in the wood and oil is sucked deep into it. The process parameters depend on the amount and type of of wood, moisture content and dimensions of the wood, so feel free to contact us via for recommendations on your deep-impregnation project!