Oil Painting Mediums
Oil Painting Mudiums
Hi, I was in your demo class today and you were talking about medium
recipes for oils. Could you please send them to me.
Sincerely, Lorraine
P.S. I really enjoyed your demo.
Thanks Lorraine. I have been asked on several occasions to discuss the use of painting mediums with oil paints, so here it is…
Many artists simply use the paints straight from the tube, painting alla prima. This is a fine way to paint. Still, the full range of possible effects in oils can only be achieved by modifying the paint with some sort of painting medium.
Some painters simply thin their paints with solvents like turpentine for washes and fine detail while others use straight linseed oil, or a simple combination of the two. In fact, some inexpensive commercial painting mediums are made of these two ingredients only. But straight linseed oil and turpentine are not good choices to use as painting mediums, alone or together. Because modern tube oil colors are made with only Linseed oil (and sometimes safflower oil) they are already proportionately too high in oil content, so you don’t want to add more! Linseed oil dries to a flexible, durable film but unfortunately it also darkens and yellows with age, and takes your colors with it! Excess oil also slows down the drying time, which can cause cracking with certain pigments and may also cause the paint film to wrinkle.
Adding only solvents like turpentine or mineral spirits to dilute the paint weakens the paint film by spreading the oil too thin. A thin layer of ‘lean’ paint is no longer flexible and is likely to crack. The lack of oil in the paint film also makes the colors dull and opaque, and the paint film too absorbent. Any subsequent layers of paint put over top of this ‘lean’ layer will also darken as too much of the oil will soak into the thinned-out layer underneath.
There are some good ready-made painting mediums on the market but they do not normally list the ingredients. Buy good quality mediums (the expensive ones) and you will probably get good results. Winsor & Newton makes a good painting medium called Liquin, it is made with an alkyd resin. Alkyd resin is used in commercial house paint as well. It is chemically compatible with oil but dries fast and clear.
It is easy to make your own painting medium and most art supply stores carry the raw ingredients. The advantage of making your own is that you know what you are getting and you can make mediums to suit your own needs and painting style.
A good painting medium has at least three ingredients: oil, a solvent, and a resin. I don't recommend making mediums with anything but polymerized oils (stand oil, or sun-thickened linseed oil) because they dry faster, clearer, and form a more durable paint film than raw linseed oil. Pure Gum Spirits of Turpentine or Rectified Turpentine are the only solvents that should be used in a painting mediums. Unpurified solvents like those available in hardware stores will have unpredictable results. Also note that natural resins like Damar cannot be diluted with mineral spirits. Damar resin is considered the best all round resin for oil painting mediums. Mastic and Copal are also used to make mediums. A drier like Cobalt Drier can also be added in small amounts to the medium.
Here are some guidelines to remember when making your own mediums. Use them to help you make adjustments in your recipes to suit your style or a particular effect you want to achieve:
- Polymerized oil (Stand Oil, Sun-Thickened Linseed Oil): oil gives the medium elasticity and durability. With too much oil in the medium the paint film will dry slowly and darken and yellow with age. Not enough oil and the film will be too brittle and will tend to crack and flake.
2. Resin (Damar, Copal, Mastic, Venice Turpentine): The addition of resin to the paint film makes the colors brilliant and more transparent. The resin speeds up the drying time and makes all colors dry at similar rates. Not enough resin in your medium and the paint will dry slowly and it will look duller. Too much resin and the paint will be too sticky to handle and the dried paint film will be too brittle and hard. Copal is a very hard resin and does not readily dissolve in turpentine.
3. Solvents (Pure Gum Spirits of Turpentine or Rectified Turpentine): Solvents help make the medium more manageable by thinning it out. It also helps to blend the resin with the oil. Too much turpentine will make the medium thin and it will lose its luster, adhesive strength, and flexibility. Not enough solvent makes the medium too thick and difficult for use in glazes and fine detail painting.
Here is a recipe for a good all round oil painting medium from Ralph Mayer's “The Artist’s Handbook”:
Damar varnish (5lb cut) - 1 fluid oz.
Stand oil - 1 fluid oz.
Pure Gum turpentine - 5 fluid oz.
cobalt drier - 15 drops
Do not add more Cobalt Drier if you want a faster drying medium, excess dryer may cause the paint film to shrink and crack. Instead, increase the amount of turpentine. Another recipe that I like uses Venice Turpentine (a resin) instead of Damar resin. This one dries very clear and brilliant and is good for glazes.
1 part stand oil
3 parts venice turpentine
1-3 parts turpentine (can be varied according to fat over lean principle)
A variation of this that would dry faster is to mix 2 parts Venice Turpentine and 1 part Damar to 1 part stand oil. Warming the stand oil and Venice Turpentine is necessary to mix them easier.
