History and development
25 years ago almost all knowledge concerning linseed oil had disappeared. During that time reports began coming in saying that the houses we had been building were now in poor condition. The wooden facings beneath the plastic paintwork were rotting. The paint was cracking and flaking. The repercussions from the 60s and 70s were now being felt.
At the same time:
The Central Office of National Antiquities in 1984 published a collection of ingredients for a number of linseed oil paints. Swedish farmers were looking for areas in which to diversify and linseed oil once again came back into fashion. Environmental debates supported the development of recyclable binding agents and linseed oil fulfilled this demand.
Background and development
Between the years 1981-86 I attended art college in Malmö. Amongst other subjects we received instruction on how to make paint for applying on canvas. The teaching was quite general but I immediately became fascinated and acquired a feeling for the subject, which later proved crucial for my future career. Knowledge about linseed oil and colour pigments was still alive amongst the artist fraternity but had almost disappeared amongst professional house painters. At the time I was unaware of this fact until 1988 when I received an inquiry from a builder as to whether I would be able to make linseed oil house paint.
I had no ambition to manufacture linseed oil paint on a large scale but as a professional artist it would certainly be a boost to my otherwise poor economy.
In 1989, I founded a private company concentrating on art, teaching and the production and sale of paint. I had quite a number of exhibitions of my own work as well as further inquiries about linseed oil paint both from artists and builders. I sent away for foreign literature on the subject and also visited older painters with traditions and knowledge on the subject who proved willing to share what they knew and which otherwise was unobtainable in books. No other education was available other than through word of mouth, experimentation and evaluation.
Although many still believed that there would be no future in linseed oil paint, I was lucky enough to acquire the necessary machinery for its production. It had been standing idle at various paint factories or left in storage, so I was able to purchase it at a reasonable price.
During the 1990ies, interest in linseed oil paint began to increase and it became necessary to employ a staff in order to meet the demands. In 1996 the premises in Genarp were further extended and in 2001 a piece of land was purchased in the industrial estate and the linseed oil paint factory was built. At the same time the company was renamed Ottosson Färgmakeri AB. As we are very seasonally dependant, the number of employees varies. In the summer 6 people were working for the company. This year we will produce approx. 80 tons of linseed oil paint.
We have more than 50 distributors operating in Sweden, Norway and Germany.
The raw products
To manufacture a product of such high quality demands good raw products. The linseed oil which we use is cold pressed oil. This means that the linseed is pressed without it first being heated up. The oil obtained is so-called “virgin oil” which is the best as the amount of saturated fatty acids and other sludge material pollutants are less. The oil from the linseed we use is cultivated in southern Sweden. The area around the Baltic Sea has an excellent climate for the cultivation of flax from which linseed oil is produced. It can only be grown in temperate climates with Canada being the world’s largest producer.
The linseed oil which leaves the press is called raw linseed oil. We use this raw linseed oil for diluting the primer paints which require an extra impregnation effect. It is also used as one of the main ingredients in the manufacture of our artist oil paints.
In order to improve the drying capacity of linseed oil, the raw cold pressed oil is heated up together with a certain percentage of metal salts, e.g. cobalt, manganese to improve the oxidisation process.
During the heating process air (oxygen) is added. Unlike water linseed oil does not boil at 100°C but will increase its temperature successively until it self ignites at 350°C. Therefore it is extremely important to control the temperature during the “boiling” process. The linseed oil we use has been heated up to 150°C. This is retailed under the name Swedish cold pressed boiled linseed oil.
Boiled linseed oil has a somewhat higher viscosity than raw linseed oil but has extremely good absorption and adhesion qualities on the substrate when compared to modern binding agents such as acrylic and alkyd.
The colour pigments
In order to achieve good results, the selection of colour pigments is of greater importance than the choice of linseed oil.
The selection of colour pigments has never before been as great as it is today. Many “new” pigments have as yet never been tested together with linseed oil. This presents a great challenge in choosing the right type and quality.
90% of the colour pigments we use are non-organic. They consist of different metal compounds and are of a particular grain size. This applies, for example, to the naturally occurring earth pigments zinc white, titanium white, the iron oxide pigment etc. These pigments have the best light non-sensitivity and a great deal of knowledge has been gained in how these pigments function.
Following the developments made in organic chemistry during the 1990’ies, valuable contributions were made towards introducing new pigments with good properties. For example, in order to increase our colour range we now use monstral green, monstral blue and quinacridone magenta.
When choosing a pigment it is important to determine whether or not the pigment has been “tainted” i.e. no cheaper filling pigments have been added. In order to illustrate this point I can explain that when I first started this enterprise I purchased pigment “green umber nr.30”. This particular pigment was included in the 1984 colour samples supplied by the Central Office of National Antiquities and was therefore approved for use.
When producing the paint using this pigment a large problem was encountered when it came to storing it in pots. The pigment sunk to the bottom resulting in it forming into a hard dry clump. On examination it was discovered that the pigment was actually a mixture of green umber and large quantities of a cheaper heavy spar material used as a filling agent, i.e. a white pigment which when mixed with linseed oil becomes colourless and transparent and subordinate to the main colour pigment. A natural umber is a soft light pigment which does not sink to the bottom when stored. Today we use natural green umber nr. 786 from Italian earth instead.
What are the consequences of tainting pigments other than those of storage?
The answer is they effect the aging process of the paint. When the surface of the linseed oil is broken down by the sun, the deep gloss associated with linseed oil is lost and the pigments return to their original state (dry pigments). Filling pigment is white when not mixed with linseed oil and as a consequence the aging paint becomes much lighter and chalky in the absence of linseed oil.
In addition, the filling material also effects the elasticity of the paint resulting in it not having the same capacity to cover.
Production
How is linseed oil paint produced? This depends on the pigment being used and the intended use of the paint. Linseed oil paint is the type of paint which allows the greatest variations without it being defective.
The necessary know-how lies in the control and balance between the linseed oil, pigment and solvent used within the process.
Each colour pigment has an individual oil number associated with it in order to control the amount of linseed oil used in relation to the pigment. Some pigments require a large amount of linseed oil in relation to their weight, others require less in order to achieve a paint paste of equal viscosity. This paint paste can also have the peculiarity of changing viscosity itself when stored over a long period of time, becoming either thicker or thinner as a result. The characteristics of linseed oil can also vary from season to season and this too can have an effect on the linseed oil/pigment balance.
These variations mean that there must always be a degree of suspicion directed towards the paint materials and that it is not always possible to expect everything to turn out exactly the same each time. This is something that both stimulates and keeps you on your toes.
In the production of our base paints, i.e. when we produce paint from a single toned colour pigment and linseed oil, we choose the working method best suited to the characteristics of the pigment concerned. We utilize the machinery which mechanically produces the paint mixture with the best properties.
Many earth pigments such as yellow ochre are quite coarse and the grain size requires certain modification in order for it to function within the linseed oil paint. That is why a rolling mill is used to distribute the pigment. This “paint grinding” process transforms the pigment/linseed oil from a thick course substance to a smooth and even product.
As the mixture is still too thick to be used as paint, more linseed oil is added in order to give it the desired consistency. The drying agent (siccative) is also added to help the paint become dust-free after approx. 1-2 days.
These base paints are coloured and contain only the respective colour pigments and linseed oil. (In modern types of paint, white bases are used to a greater and lesser extent, to which a toner is added in order to achieve the required shade).
When special tones of paint are required, the mixing is conducted freely using hands and eyes only. A special order might involve an old flag colour or some other original shade which we attempt to copy using only our acquired skill and knowledge.
Apart from the linseed oil we produce for house painting purposes, we also produce linseed oil paint for artistic painting. The paints are intended for use for traditional artistic oil painting, decorative painting, graining and marbling, as well as for tinting our house painting range. The paints are produced using a roller mill and filled into tubes. With a small amount of boiled linseed oil, the paint can also be diluted to acquire the consistency, characteristics and area of use of our other linseed oil paint products
Future
Interest in linseed oil paint has increased greatly since I began and the trend seems to be continuing. Knowledge about this type of paint, which 20 years ago had almost disappeared, is now slowly gaining momentum. It is through experience and usage that we are best able to learn.
The colour samples which the Central Office of National Antiquities produced in 1984 have been increased and revised this year through Teknisk Målerikonsult Sven-Olof Hjort who, in cooperation with ourselves, has compiled the colour sample chart “Linseed oil paint 2003”. This colour sample chart containing 367 different colour shades, is now available on the market.
Many believed that linseed oil paint would never again return to popularity. The same people also said that it was only a passing trend that would quickly blow over. However, just the opposite seems to be the case. Linseed oil paint has established itself as a strongly competitive alternative to more modern developed paint systems. This is true from both an economical as well as an aesthetical point of view. In other words, the future looks very bright indeed for linseed oil paint.