To painters, discussing mediums can be like a political debate. There are pro-Maroger, anti-Maroger, pro-natural resins and anti-natural resins, as well as pro-alkyd and anti-alkyd proponents. The disputes are always about potential cracking, lack of adhesion and yellowing. I have always been the curious type and have experimented with almost every medium that I could get my hands on. However, if you are new to painting, the best approach is to experiment with the paint right out of the tube so that you can understand and fully integrate into your procedure what the paint can do without additives.
[FONT=tahoma]Giverny, Monet's Garden, Kenneth Freed, oil on canvas[/FONT]
In this article, I have tried to list some of my thoughts concerning the subject. Much is left out and much is ignored, but I thought there might be something here to encourage a discussion. I have spent considerable time during my 40-year career, experimenting and attempting to understand how different mediums work and why a painter would choose to use them in the first place. All of the statements that I make in this article are opinions or conclusions drawn from years of trials, experimentation and, in some cases, constant use. Some of the statements are very general because whether the mediums work for you like they do for me are related to environmental issues (i.e., substrate, ground, etc.).
Salvador Dali, in his book 50 Secrets of Magic Craftsmanship, indicated that oil painting is about controlling the viscosity of paint. It has taken many years before I fully realized the impact of what he was saying. Mediums can be used for different purposes. Artists use mediums in alla prima painting to change the working properties of the paint. This would include making it dry faster, more slippery, tacky (increase drag), glossier, mat, or simply changing the viscosity of the paint. Some painters like to put a few drops of medium in their paint, some like to dip their brush occasionally (I refer to this as a “migratory dipper bird”), and some like to create a wet cushion to work into. Of course, there are a fair number of alla prima painters that use no medium at all. The working properties of oil paint without medium in various states of drying on the palette can also be interesting. For the first ten years of my career, I was an alla prima painter. When I used mediums during this period, I used the “migratory dipping bird” technique. This was not particularly efficacious because some areas became quite oily and glossy and some areas drier, causing a non-uniform surface with varying surface characteristics and resulting problems of adhesion uniformity.
In layered painting, the basic reason to use mediums aside from the mechanical benefits is to create a translucent series of layers or glazes. Mediums help create translucent passages that appear like pieces of stained glass window stacked on each other. The nature of the medium and how much color is loaded onto the brush determines its opacity of translucency. If the brush is loaded or choked with paint, then quite probably the paint layer will be more opaque. In general, depending on artist’s objectives, it looks very nice to have some opaque passages in areas of light (higher chroma areas) and some transparent passages in the shadows (lower chroma areas). This gives a variation to the surface that can be nice. Using mediums for glazing is not the only way to achieve glazes but it is sometimes safer than using solvent to thin down the paint for translucency, because adhesion problems can result from under bound oil paint.
[FONT=tahoma]Self-Portrait with Bone, Kenneth Freed, oil on canvas[/FONT]
Countless mediums work very nicely together and produce wonderful results. Using and experimenting with mediums have a lot to do with the personality of the artist. Some feel that experimenting with mediums is dangerous and have done so with great trepidation. Others by nature love to try new things. There are a few basic concepts to watch out for—first, the layers must be equal to slightly oilier as you go up in layers in order to promote good adhesion. There are “degreasing” fixes that have been used and seem to work, but in general, it is better to build a layered painting with increasing levels of oiliness. I have had success in labeling mediums by percentage of oil excluding balsams, resins or siccatives in the calculations. However, you must take into consideration the amount of solvent, which has an effect on the percentage of oil in the medium.
In experimenting with mediums, one of the most important considerations is the viscosity of the medium for the conditions of the painting. Viscosity must be adjusted for the following:
[LIST][*]the substrate that you are working on;[*]the type of ground;[*]environmental conditions of heat and humidity; and[*]the type of the brushes.[/LIST]Let’s break this down. Panels are generally more slippery than canvases with its woven texture. Paper also is smoother and slippery, depending on the ground used. Canvas usually has a bit more drag unless the ground is scraped on to simulate a panel to cover up its texture. Acrylic grounds vary in their degree of absorbency, depending on the formulation, and offer considerably more drag than oil grounds. Hot and dry climates seem to set mediums faster and provide a little more drag than colder, more humid climates. Soft-hair brushes, such as Kolinsky and nylon are often better for glazing and scumbling. Hog bristle brushes tear up glazes and make smooth translucent layers difficult to achieve. The physical properties of working mediums should match the conditions that you have set up. When the medium is in harmony with the conditions you have set up, namely the substrate, ground, brushes, environmental conditions, then a certain nirvana takes over and the brush glides perfectly over the painting surface.
There are hundreds of medium components all of which have different viscosities and working properties. There are oils, balsams, resins, gums, waxes, solvents and driers. You can find copious amounts of technical descriptions about the make-up and manufacture of medium components in many different books. Therefore, I won’t duplicate much of which has already been written. I will make a few observations about the various components.
Cold-pressed linseed oil
Acid-refined linseed oil
Alkali-refined linseed oil
Stand oil (bodied oil)
Boiled oil (oil with driers)
Sun-bleached linseed oil
Sun-thickened linseed oil
Poppy seed oil
Cold-pressed linseed oil is quite yellow in appearance and has naturally occurring impurities called “foots.” Refined linseed oil is paler in appearance and without the impurities. Each has their own advocates. I suppose it comes down to a trade off. Most users would never experience the differences because from the standpoint of viscosity they behave similarly—slippery and oily. Stand oil and sun-thickened oil is more viscous like honey or thicker, depending on the manufacturer. The viscosities of these oils differ greatly. Panels with oil grounds are easier to paint on with oil that is more fluid due to its smooth semi- or non-absorbent surface. Canvases with acrylic based grounds have texture and can benefit from oilier cuts like perhaps cold-pressed oil. It is good to know the properties of the individual components in the medium but the determining factor is the viscosity of the combined components.
This list of oils is not meant to be all-inclusive, but contains some of the oils with which I have experimented. Poppy seed oil is a pale oil and a bit slower in drying than other oils; it also forms a slightly less strong adhesive bond than linseed oil. What I like about both poppy seed oil and walnut oil (apparently so did Leonardo da Vinci) is that they dry slower and are very effective in seamless blending of layers. I have felt that their smooth blending abilities particularly walnut oil is wonderful in producing smooth gradations of tone. I have generally stayed away from sunflower and safflower oils, although they are used by art materials manufacturers to make light colors. They are slow driers and do not offer mechanical advantages over poppy seed or walnut oils.
Clove oil is an interesting product. It can keep paint wet for 20 to 30 days. At one point in my career, I did these unbelievably complex palettes of many colors. I added clove oil to my colors and kept these mixes wet on the palettes for nearly a month. Then I used a wet cushion that included quick drying mediums, so I had wet paint on the palette and dry paint on the painting surface—the best of both worlds. This was a passing phase for me; I would not recommend such bizarre approaches. However, clove oil does have the ability to keep paint wet for an extended period—longer on non-absorbent grounds and slightly less time on absorbent grounds.
I have tried all three. Oregon balsam can be a little dark. All are viscous substances that increase the viscosity of mediums. I have used Venetian turpentine more often due to its availability and performance. I generally reserve Venetian turpentine for the upper layers. It produces a wonderful glossy paint film and has excellent physical properties for blending. It really does not seem to affect the oil content of the medium for calculation purposes, but it should be reserved for the final layers in a multi-layer painting, otherwise the surface may become too glossy and subsequent layers, unless they are fatter in oil content, may not adhere properly. Canada balsam has its advocates that consider it superior to other balsams.
One of the major concerns throughout the history of painting involves natural resins, which are primarily used to make varnishes. Varnishes are not just used for the final coating of paintings; they are an integral part of mediums. Damar and mastic are soft resins; copal is a semi-fossilized or fossil resin; and amber, the hardest of the resins, is fossilized and made into a varnish with great difficulty, expense and heat. There are other inferior resins used from the 1400s on and many of the problems in painting caused by natural resins (in my opinion) are due to their use and inconsistent production.
Ideally, a medium should do a few things in the best of all possible worlds. First, it should resist cracking and strengthen the paint film. Second, it should promote good adhesion. Third, it should resist abrasion. Fourth, it should not yellow. It can impart gloss, thereby increasing color saturation, and promote drying of the paint film. The resin that meets these ideals is one not available to the old masters. It is synthetic, alkyd resin. It is available in numerous mediums, including Winsor & Newton Liquin and Gamblin Galkyd. My belief is that alkyd resins are perhaps the greatest innovation for the oil painter since the 1400s. I discovered early on that if a small amount of alkyd resin was used in the medium pf multi-layer painting it built very strong, uniform layers and offered all the benefits mentioned above.
I have tried amber and it is a nice product that dries very hard. However, it offers no additional benefit beyond alkyd that also dries extremely hard. I would also be willing to bet that on canvas with its expansion and contraction, alkyd would have a tendency to crack much less frequently than amber. The other problem is amber is very expensive. Copal has advocates, including the late Frederic Taubes, but it is so inconsistent in manufacture that you never know how well it’s made. Softer resins like mastic and damar are fine in some mediums. Maroger’s medium, which contains mastic, is a pleasure to use and I have had no ill effects in its use on panels. Generally, I do not use it on canvas. Soft resins may work well as final picture varnishes, but they cannot stand up to the superior qualities of alkyd resins for use in medium formulations. As such, I have had virtually no layer failures with many different medium components when an alkyd is used in the formula.
[FONT=tahoma]Prepared Wax Mediums[/FONT]
Dorland’s Wax Medium
Gamblin Cold Wax Medium
Rublev Colours Wax Medium
Maroger’s “Titian” wax medium
I have frequently experimented with wax-based mediums, including those I made, because I like my canvas paintings to have a slightly mat appearance but my panel paintings to be glossy. One of the things that I have been working on for some period is creating a translucent glazing medium for a wet cushion that is strong, resistant to cracking and slightly mat in appearance. Dorland’s Wax Medium seems to be all right as an additive to the paint to make it mat but I have not used it much. I have more frequently used Gamblin Cold Wax Medium, which is a wonderful product to add to paint to reduce gloss. It sets well, keeps fresh on the palette when covered and seems resistant to cracking. However, I also needed a glazing medium used as a wet cushion that would render paint layers translucent and mat. I achieved this through a home cooked medium of unbleached beeswax, Galkyd, raw linseed oil and Turpenoid. It produces an incredible medium for mat translucency. The interesting thing is that because it is matte, it does not seem to show the layering to the same extent as gloss mediums. You get an incredible range of optically blended values, hues and chroma without the appearance of a heavy glossy glaze.
Maroger’s wax medium, which includes black oil and beeswax, is a wonderfully sensuous medium to use when added to the paint on your palette and due to the presence of lead dries quickly.
Spirits of gum turpentine
Mineral spirits, odorless or low odor
I have rarely used spirits of gum turpentine in mediums unless I use damar, which doesn’t like mineral spirits and is not easily soluble in it. The odor of turpentine is too strong for many artists that work long days. Most all medium formulations will work well with mineral spirits.
I have used spike oil as an additive to palette paint, if I wanted to refresh a color that was in the process of drying. The interesting property of spike oil is its perfume-like smell and the fact that it volatizes more slowly than other solvents. That is an advantage in some techniques.
The percentage of solvent has an effect on building layers in a painting. A greater percentage of solvent will dilute the amount of oil causing bubbling up and lack of adhesion. A decreasing amount of solvent is necessary as you go up in layers unless you completely change the constituent elements of your medium formulation. I like to label my mediums by percentage of oil but I am also very aware of the amount of solvent by percentage in each one.
I have concluded that in using mediums, it is more effective to put some in your paint to change the viscosity, or use as a wet cushion or both. The least effective way of using a medium is to dip into it (migratory dipper bird) because you cannot control its uniformity and the resulting problems that occur.
I have completed paintings that have 12 layers and that for one to three layers I used the same medium or percentage of oil before the painting seemed to require more oil. It does not have to be much more oil, just a little oilier. (Remember, viscosity conditions must be tuned to the substrate, grounds, brushes to be used and environmental conditions.)
Virtually any combination of the above materials can be used if alkyd is part of the formulation. Be sure to label mediums by percent of oil in the formula and take into account solvents by percent that influence the dilution of the oil. Ignore balsams and varnishes in your oil calculation but consider them as a percentage of the total medium ingredients.
The superior quality of alkyd is a uniting force in all multi-layered paintings. I would stay away from softer resin varnishes. There are many books written which give different formulas for mediums, so I won’t list them. Be creative, don’t be afraid to experiment and take notes on what seems to work. Be aware of the viscosity of the medium for the specific substrate and ground. If your brush drags too much, add more oil, solvent or both to make the right medium. If it feels too slippery, consider adding more resin or balsam (especially in the upper layers). Be sure that each successive layer is equal in oil percentage or slightly greater for proper layer building and adhesion. Above all, don’t be afraid. No one will die. The police won’t arrest you. You may discover a wonderful combination of materials with exactly the right viscosity to produce a masterwork. And, if the wet cushion that you apply doesn’t seem quite right, wipe it off, and reformulate it to get the viscosity and working properties you like. Cheers.
Now those whose job it is to patrol such bastions of inexactitudes and generalizations will have lots to critique in my words. That’s okay. Take it for what it is worth and realize that because of the number of variables in substrates, grounds, brush types and environmental conditions, it is hard to make iron clad statements about what will work under all conditions. What I have tried to do here is inspire thought and questions, and give some practical conclusions drawn from much experimentation. I have not tried to list the chemical formulations of the above medium components; others have done that in technical manuals. I have tried to give practical usage guidelines on a much more informal basis as well as promote the idea that medium usage can be as creative as the actual paintings.
Written by Kenneth Freed.