Background information

Below you can find background information about linseed oil paint including what you should think about when using it, how it should be handled and the meaning of certain specialist terminology.  

The list is presented in alphabetical order.

ADHESION Linseed oil has fantastic adhesion properties and in general adheres to all surfaces. In our experience the paint adheres well when used on other types of paint.   

APPLICATION Linseed oil paint should always be applied thinly. The paint does not spread out itself but must be distributed evenly using a paintbrush. The paint can also be applied thinly on even surfaces (e.g. sheet material, metal, smooth plaster) using a roller.

BLOTCHES occur when the linseed oil absorbs into the underlying surface and the colour of the paint appears darker in shade. When absorption is uneven, it can result in a blotchy bright/dull, light/dark surface. In order to achieve an even result, the underlying surface must absorb evenly. Surfaces which absorb unevenly must first be prepared so that they absorb evenly before the final coat is applied. Excessive dew formation can also cause blotchy results, therefore avoid painting during damp autumn evenings.

CLEANING of hands and paintbrushes is best done using soap. Solvents can also be used.

ECONOMY To understand that linseed oil paint is a cheap alternative, it should be compared with other types of paint per square metre rather than per square litre.

FIRE RISK Rags soaked in linseed oil can spontaneously combust. Soak the rag in water after use and dispose of it in a container with a lid.

FURROW FORMING on the paint surface is an indication that the paint has been applied too thickly. Furrows often occur in profiles where too much paint can easily collect.

GLOSS After three coats the paint has a high gloss finish which will gradually become more matt until after approx. 3-4 months when it will have acquired its final semi gloss finish (gloss scale 30-40). Often when painting indoors, the high gloss finish is noticed immediately after applying the final coat but already after a week it will have acquired a more matt finish.

MOULD/ALGAE ATTACK on the paint surface is unusual but may occur outdoors. Most often it appears as small black dots (of earth character). This is located on the surface and, other than aesthetical reasons, will not effect the paint’s function. Should the attack be intensive and troublesome, wash it away and apply a new coat of paint. The attack could be due to dampness, heat, an already effected substrate or an excessive application of linseed oil on the surface. Zinc oxide is used in all our linseed oil paints.

OXIDATION/DRYING takes place when linseed oil comes into contact with oxygen in the air. Light and heat accelerate the process. Drying takes place fastest outdoors during the summer months. Normally, linseed oil paint dries between 1-3 days. Provide good ventilation=oxygen ventilation when painting indoors. In an unheated dark cellar, the paint dries very slowly. The cold delays the oxidation process but if there is sufficient oxygen and light, the paint will dry well. The underlying surface must be dry with a moisture content below 15%.

PIGMENTS used consist both of naturally formed, so-called earth pigments and man-made, so-called synthetic pigments. The requirement is that they should not be sensitive to light and air.  All earth pigments fulfil this requirement but e.g. the synthetic pigment ultramarine is sensitive to oxygen in the air and can whiten somewhat outdoors.

SHELLAC is a spirit soluble secretion obtained from an Asiatic insect. In painting terminology (often referred to as knotting varnish), it is used to insulate knots and resin flakes on wood indoors prior to painting. If shellac is not used, the resin can penetrate through the painted surface and result in discolouration in the form of brown stains. Shellac is applied quite plentifully 1-2 times and can be painted over after half an hour. Should the resin continue to penetrate after painting, then apply shellac on the painted surface afterwards.

SOLVENTS/DILUTION With some exceptions (see the colour samples), the paints contain no solvents. In cases where dilution using solvents is indicated, we refer to Balsam turpentine (oleo-resin balsam), which consists of 100% vegetable turpentine, distilled from conifer resin. Turpentine has the ability of transporting oxygen which improves the drying process. The use of mineral solvents such as white spirit and aliphatic hydrocarbon spirit has also shown good results. When painting indoors, it is important to observe the safety directions concerning the respective solvents. In certain cases, solvents can be totally excluded (see the technical directions).

STORAGE of linseed oil paints can take place indefinitely providing no oxygen comes into contact with the paint. When storing paint in a damaged container, cover the surface of the paint with a plastic bag and replace the lid securely so that no air can enter. The paint is best stored in a cool place and it is able to withstand frost. During long storage periods the colour pigments can sink to the bottom. Therefore, make sure the paint is stirred well before reuse. 

SUBSTRATE which may consist of various types of wood, plaster, gypsum or metal must be dry with a moisture content below 15% and have a neutral pH value. Painting directly on paper or textiles is not recommended as the oxidation process of linseed oil can result in the material becoming brittle. Insolate the underlying surface first using an adhesive substance or emulsion paint. Silicon based and waxed surfaces cannot be painted.

WORKING TEMPERATURE The paint contains no water and can withstand frost. Application of the first coat can be carried out during minus temperatures providing the surface is dry and the paint is kept at room temperature. The optimal temperature for painting is 15 – 25º C. Avoid painting in direct sunlight during hot summer days.

YELLOWING Linseed oil yellows in the dark and fades in the light. This means no yellowing takes place outdoors, an insignificant yellowing will take place indoors in rooms with daylight and an intense yellowing in rooms without daylight. This yellowing process is reversible i.e. a surface that has yellowed in the dark and which is then exposed to the light will revert to its original shade and the yellowing will disappear