How to paint with linseed oil paint

Maintenance and aging, exteriors

What can you expect from a linseed oil paint on exterior surfaces? Depending on how much the painted surface is exposed to sunlight, the linseed oil paint gradually fades. This can be seen first on the south sides of a house, which receive more hours of sunlight. The reason that the paint becomes matte is that the linseed oil is broken down by the sun’s ultraviolet radiation. Thus, the pigments do not change or fade; the lack of the fatty linseed oil is the cause. When the color surface loses its luster, the color also becomes a bit lighter. This is more visible in dark colors than in light ones.

If you apply linseed oil on the matte surface, the original color will return. The fact that linseed oil paint becomes dull outdoors is natural and does not require direct action. Eventually the color begins to “chalk off”, or leave a slight color residue when touched. You can draw with your finger on the surface and the pigment will come off on your fingertip. The paint surface is still intact, and the linseed oil that has penetrated the substrate protects it from the inside.

Plastic-based paints retain color longer than linseed oil paint. Plastic paint is not degraded by UV radiation; instead, it ages just like a plastic bag – and eventually decomposes into microplastic. If you expect a linseed oil paint to look and age the same way as a plastic-based paint, then you should not choose linseed oil paint.

The chalking can be positive in the sense that the paint “washes itself” as dirt and contaminants erode from the surface. For some outdoor objects, such as garden furniture, chalking off is not desirable; therefore, they require more frequent maintenance.

Linseed oil-painted surfaces that have not been maintained for a long time eventually begin to crack and the surface acquires a snakeskin-like pattern. Linseed oil paint will not peel in large flakes from the substrate, and should this happen, the cause should be sought in the substrate. The substrate may contain too much moisture, or in some cases is too oily.

Inspection and maintenance of linseed oil-painted surfaces

Annually inspect your house, windows, etc. for any noticeable changes in the painted surfaces. Pay special attention to surfaces exposed to excessive sunlight.

Washing linseed oil-painted surfaces

Before you begin maintenance and repainting, consider that washing the exterior is often enough to make it look fresh again. When washing a linseed oil-painted surface, remember to choose gentle, pH-neutral products that will not damage the painted surface. Ordinary dishwashing liquid or weak soap solutions work well. If the surface has been infested with algae and mold, use gentle products such as Biokleen Algae & Mold Remover.

Maintenance with boiled linseed oil on smooth, planed surfaces

If necessary, clean the surface with a weak soap solution and rinse thoroughly with water. Brush on a thin layer of boiled linseed oil. Wipe off the excess oil after half an hour, and the paint will have regained its original color and luster.

Maintenance with boiled linseed oil for rough surfaces

If necessary, clean the surface with a weak soap solution and rinse thoroughly with water. Let dry. Mix equal volumes of boiled linseed oil and gum turpentine and apply a single, thin layer. Check that the linseed oil penetrates the substrate, and remove any excess linseed oil with a dry brush.

When is it time to repaint?

Repainting is usually required every 8 to 15 years. It is not certain that you will need to repaint all sides of the house. Paint on north-facing facades usually lasts twice as long as paint on southern facades. See the section “Painting previously painted exterior surfaces”.

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