Masterclass Oil Paint Technique by Poen de Wijs

Poen de Wijs will not give a complete manual of materials and techniques. There have been many publications about the various pigments and their properties, about types of oil, resins and mediums, on turpentine and white spirit, about paint brushes, tassels, palettes, palette knives and palette sticks. The existing knowledge on these matters is very well documented and in this Masterclass this is definitely a thing on the agenda. But in traditional, realistic oil painting, alongside theoretical knowledge, practical experience is important. In this narrative the focuses is on that of experience.

Watercolor with its mysterious interplay of water, paper, pigment and gum, forced me (in a previous Masterclass) to impart several lyrical sentences. As light and airy as watercolor paint is to be treated, as stubborn and difficult it is to work in oil. The difference in character is found in the difference in binder and solvent. The binder for the watercolor pigments is gum, the solvent of gum is water. Oil paint basically uses the same pigments as 

watercolor, but the binder is linseed oil, pressed from flaxseed, and linseed oil is usually dissolved by turpentine (sometimes white spirit, gasoline or kerosene). Watercolor needs little binder and lots of solvent (water). With oil paint it is exactly the other way round and therefore oil is a solid mass, which allows forming, pushing, kneading and distribution.

Watercolour glides effortlessly from the brush. The compact oil paste stays sticky on the brush and can only pushed by wiping. A brush stroke will remain as it is put down, and can be transformed and distributed slowly, but will never glide naturally in soft floods. The evaporation of water and the ever changing response of the pigment during the quick successive stages of drying, forces the water-colorist to act quickly, to make swift changes and sudden interventions. On the other hand, the drying of oil is extremely slow and requires a careful, solid approach and especially patience and perseverance from the oil painter. An oil painting should be built, should grow. The watercolorist is a player; the oil painter is a builder.

After three years of art school, with teaching mainly in drawing and watercolors, finally the great day arrived when we could paint with oils. The materials were simple: some cheap tubes of paint mainly in earth tones, cadmium colors, ultramarine, madder, emerald green and titanium white, a few hog hair brushes, a palette knife, a board of wood for a palette and some white spirit for dilution. The method was simple.

A cardboard plate was smeared with cheap primer. The charcoal sketch of a still life, applied to the primer, was roughly colored with larger and smaller licks of paint, thinned with white spirit. A week later, painting could be continued. Over the first layer small dabs of undiluted paint were put side by side, more precisely mixed by color, so that a jumble of touches and spots, viewed at some distance, made representation visible.

When the teacher came to see, he always used his standard statement: “Color tones” and then he pointed at attractive and less attractive ‘color tones’. Less attractive ‘color tones’ were touched again in a third layer; sometimes a fourth layer was needed. And then the more or less impressionistic painting was finished, so simple was that! The theory with this was minimal. The different pigments, the priming of panel and canvas, the chemical properties of oils and the effect of solvents were briefly discussed. The teacher also told us something about layer-to-layer-painting, in which he emphatically pointed to ‘fat-over-meagre’-painting (always add a little more oil in the successive layers). According to him, the chemical process of hardening of layered paint was so full of terrible dangers, that in the shorter or longer term as a result, the paint crust had to crack. And so he advised us just to work ‘alla prima’ (in one layer, wet-on-wet) with as a medium, a mixture of white spirit and some slow-drying stand oil.


In the first years after my training, I still rummaged something in oil, but watercolor, in which one discovery arose after another, controlled my work. Gradually the layer-over-layer watercolor grew into Realism. I understood the relationship between layered watercolor and layered oil painting, and that aroused my interest in the technique of the ‘classics’, especially the art of the Renaissance and of the nineteenth century. But whatever I read and heard about the classical method, the technical solutions that were applied, they never totally revealed their secrets. I talked about it with colleagues; one had ever heard this, another one that. Books gave possibilities, but it was really amazing to discover that so much remained hidden.

The problem I ran across, is related to the rapid changes in art since the mid-19th century. The artist studios, where from generation to generation the technique had passed, disappeared, and the experimentation of Impressionists, Expressionists, and later the Abstractionists, did almost lose the technique in a short time. The theoretical information was still available, but the experience had disappeared. I noticed that some of the experience I was looking for still lived on in restoration circles.

One day I met a colleague who associated a lot in these circles and had researched the old techniques in practice: the painter Ab Overdam. He passed on to me some of his experiences and handed me the key to the solution of the problem, to make whole all the loose pieces of knowledge that I had collected. With this I succeeded to continue the imagery language that had arisen in my watercolors into oil. The key, Ab Overdam gave me, is the painting medium.

Oil paint is little more than ground pigment powder, combined with the binder linseed oil. One pigment may require more linseed oil than the other to obtain a paintable paste. Actually, linseed oil can be the source of major problems. If oil paint feels touch dry, it may still not have reached its final stage of drying.

The drying process, requiring oxidation to the air, until a hard vitrified layer is created, takes many, many years. In the meantime, the paint can swell or wrinkle, pull and shrink, react with the environment, to finally burst. And much more misery can arise. So why, for centuries, have artists painted in oil? What does oil have above materials such as egg tempera, resin paint, fresco, watercolours and others? Why has oil not yet been supplanted by modern acrylics? Because oil dries slowly! Precisely the cause of the problems, the slow drying, requires elaborate manipulating, forming, pressing, distribution; because of which one can comfortably built a painting. Pasty oil from the tube is thick and it can be blobbed on a surface by pushing, but it doesn’t smear really well. Some white spirit (a product of cracking petroleum) may be admixed so that the paste is smoother, but that makes the paint very skimpy. Turpentine (a distillation product of pine resin) already feels less skimpy, because it contains resin residues. Turpentine is preferable to white spirit, with is more suited to cleaning brushes. When some oil is added to the turpentine, the paint texture becomes already a lot more pleasant. Many painting mediums, which are readily obtained from stores, simply consist of oil and turpentine.

There is another ingredient that can be added through a painting medium to oil paint, namely resin. Resin dissolved in turpentine creates varnish. Varnish dries quickly and is transparent. When some varnish is added to oil, it is more transparent and dries faster. 

Varnish instead of oil makes the paint less fat and spreadably smooth. There remains however the question: what type of oil, in combination with what type of varnish and in what proportion, provides a useful painting medium? Should you take raw, bleached, cooked, thickened linseed oil, and should you choose copal, dammar, or mastic varnish? Or should you seek your salvation in other oils and varnishes, which may or may not have additional ingredients added? This question has occupied many painters throughout the centuries and can’t possibly be answered unequivocally. Many recipes for painting mediums have been developed. The seventeenth century medium that Ab Overdam handed to me, is a fairly simple solution to the complex problem:
–  one part mastic varnish mixed with one part lead oxide-boiled linseed oil.

Well, simple? The mastic varnish is for sale, but the (fast drying and highly toxic) oil should be homemade. I’ll spare you the details. Likely, for many painters the making of this alchemical concoction may be too complicated for them and for those an excellent alternative exists: the ready-made painting medium LIQUIN of Windsor & Newton. The painting medium LIQUIN (I myself used for many years the seventeenth century medium) has very pleasant properties for realistic painters:

– The drying of oil, under the influence of the medium LIQUIN, happens quickly.  A thin layer is already paintable after several days; and the curing is particularly stable.

– The medium is suitable for all layers in the painting.

– A little bit of medium added to the paint, gives a smooth spreadable mass of paint, while the opacity is maintained. A bit more medium makes the paint semi-transparent; adding more medium makes the paint transparent.

    • In particular, the three forms, opaque, semi-transparent and transparent are very important for realistic painting (see videoclip).

Painting in one layer (wet-on-wet or ‘alla prima’) has many problems that must be solved simultaneously. Loose brushstrokes shouldn’t only indicate color, they also need to express shape, and should also depict light and dark. However, color, form, light and dark are also separable. From the

Renaissance to Impressionism a style of painting was developed, in whichthese problems, as it were, were divided into layers, and could be resolved step by step: one layer for the form, one layer for light and dark and one or more layers for the colour. This method of construction was clever and very effective. This ancient technique remains usable in contemporary Realism.