Linseed oil paint glossary
Application
Linseed oil paint is always applied thinly. The paint does not spread out on its own; it must be well distributed with a brush. The paint must be applied in an even layer. If the paint is applied in different thicknesses on the surface, this will be revealed by uneven gloss. The paint can also be applied in thin layers on smooth surfaces [such as sheet metal, metal, or smooth plaster] with a paint roller . In general, linseed oil paint can be applied with many different methods and tools, as long as it is done in thin layers.
Working temperature
The paint contains no water and can withstand frost. Base coats can be applied in minus temperatures, but the surface must be dry and the paint must be kept at room temperature. The best temperature for painting is 15–25 °C (59–77°F).
Fire hazards
Rags soaked with linseed oil can ignite spontaneously. Soak the cloth in water after use and put it in a container with a lid.
Economics
If you calculate the price per square metre instead of price per litre, you will be surprised how inexpensive linseed oil paint is. Linseed oil paint is sufficient for 2 to 3 times the coverage area per litre compared to other paint types.
Gloss
The paint will acquire a high gloss after three coats, but the shine dulls gradually, and after 3 to 4 months, the final finish will be semi-gloss (gloss number 15–30). When painting interiors, you may react to the high gloss number immediately after the final coat, but already after a week you will see that the color will begin to mellow.
Yellowing
Linseed oil turns yellow in the dark and fades in exposure to light. This means that no yellowing occurs outdoors, insignificant yellowing occurs in interiors with daylight, and strong yellowing occurs in rooms without daylight. This yellowing is reversible; a surface that has turned yellow in the dark and then exposed to light fades back, and the yellowing disappears.
Unevenness
Unevenness occurs when the substrate absorbs the linseed oil paint and the color appears darker in some areas. Uneven absorption shows up as a mottled appearance, such as matte, glossy, light, and dark spots on the surface. Especially when painting interiors, where greater demands are placed on an even finish, this mottled appearance in priming and intermediate coats can cause concern. This is most clearly seen in gray shades. Spot-prime highly absorbent areas to create an evenly absorbent surface before the final coat is applied. Observe sufficient drying times and apply the paint evenly. Unevenness can also occur in cases of heavy dew formation. Avoid painting on damp autumn evenings.
Storage
Linseed oil paint can be stored indefinitely, provided that no oxygen comes into contact with the paint. If you want to store opened paint containers, cover the paint surface with a plastic bag and tap the lid firmly in place so that no air can enter. The paint is best stored in a cool place and can withstand frost. During a longer storage period, color pigments may sink to the bottom of the container. Therefore, stir the paint very well with new use.
Solvents/dilution
The paint does not contain solvents except in a few cases [see color samples]. In cases where dilution with solvent is required, we refer to balsam turpentine, which consists of 100 % vegetable terpenes and is a distilled coniferous resin. Turpentine has the ability to transport oxygen, and this improves drying. Users who have diluted the paint with mineral solvents, such as white spirit and aliphatic naphtha, have also achieved good results. When painting indoors, it is important to follow the safety instructions for all solvents. A solvent is a technical aid that facilitates the painting work. Many of our customers use our paint without diluting with solvents, with good results.
Mold & algae infestation
Mold & algae infestation on the paint surface is unusual but can occur outdoors. This often looks like small black dots [mildew]. These are superficial; they do not directly affect the function of the paint and affect only the appearance. If mold/algae is severe and troublesome, wash it off with algae/mold cleaner. Detergent also works. Mold and algae may be a sign that the wood itself has been attacked. Mold attacks from the surrounding environment are difficult to trace. It is known that old, dry grass is one cause. The attacks differ locally and the extent varies from year to year. We do not add fungicide to our paints. Zinc oxide, which we believe has a more long-term effect, is included in all our linseed oil paints.
Oxidation & drying
Oxidation and drying occurs when linseed oil comes in contact with oxygen in the air. Light and heat accelerate the process. Generally, linseed oil paint dries in 1 to 5 days depending on the external conditions. The paint dries best outdoors during the summer. When painting indoors during the winter, we recommend that you add 2 teaspoons of extra desiccant per litre of paint. In a dark, unheated basement, the paint will dry very slowly. Cold delays oxidation.
Pigment
Traditionally, inorganic pigments have always been used for linseed oil paint. Such pigments are, for example, all earth pigments, iron oxides, and other metal compounds. In recent years, environmental legislation has banned cadmium, chromium, and lead in building paints. They used to be common when intense colors were required. Modern research has now developed new, environmentally approved inorganic pigments that Ottosson use.
UV light
The natural pigments that Ottosson use in their paint are far more resistant to UV light damage than the synthetically manufactured pigments that are used in acrylic paints. So Ottosson linseed oil paints are far more resilient than acrylic paints to the harsh UV light which occurs in New Zealand.
Cleaning
The best and gentlest way to remove the paint from your hands and brushes is to use Ottosson linseed oil soap and water, but ordinary soap works aswell. Solvents can also be used. DO NOT use soap on painted surfaces!
Wrinkling
Wrinkles on the paint surface after painting indicate that the paint has been too thickly applied. Wrinkle formation often occurs in areas where excessive amounts of paint easily accumulate. If the paint is cold, it thickens, and the risk increases that the layers will be too thick.
Shellac
Shellac is an alcohol-soluble secretion from an Asian scale insect. In painting contexts [often called knot sealer], it is used to seal knots and resin-rich areas of wood indoors before painting. If shellac is not applied, the resin can penetrate the paint surface and cause discolorations in the form of brown spots. Shellac is applied primarily on pine. Spruce is considered to pose less risk for resin seepage. Shellac is applied in relatively generous amounts 1 to 2 times and can be painted over after half an hour. If resin penetration still occurs after painting, it is possible to shellac afterwards on the painted surface. Shellac can also be used on strongly absorbent spackle to reduce absorption in the substrate.
Surface
The substrate, which can be different wood materials, plaster, or metals, must be dry. It must also have a moisture content below 15 % and a neutral pH value. Painting directly on paper and textiles is not desirable because the oxidation of linseed oil can make the material brittle. Seal the substrate first with whitewash or emulsion paint. Silicone-based and waxed surfaces cannot be painted over.
Adhesion
Linseed oil has fantastic adhesion and adheres to virtually all surfaces. Our experience is that linseed oil paint has very good adhesion on surfaces painted with other types of paint.