|Classical Oil Painting Mediums
Written by Jodi J Brody
Mediums are a great "tool" for the classical oil painter, when they are made and applied properly. There are many that have been premade for the retail market that are available, and ready to use as is, right off the shelf. There are also extremely complicated, and sometimes dangerous recipes that the artist can make themselves, if they dare.
I would like to show you how to make some simpler ones that do not involve "cooking" the mediums, and can use items that are readily available to most artists either from their local art store, or from online sources.
Let's Get Started:
The questions I will try to answer are:
1. When does one use these mediums?
2. Which ones can the artist use to get a particular result?
3. What are some of the recipes that can be made, easily, and safely, at home?
The various oils used as mediums in oil painting are known as drying oils. The term is useful as a reminder that different oils have different drying times and properties. These mediums are mixed with oil paint both to modify the way the paint handles straight from the tube (for example, make it thinner or lengthen the drying time) and to alter the character of the paint from what you get straight from a paint tube (for example, make it transparent or opaque, gloss or matt). Ideal mediums are colorless, permanent, flexible, and do not influence the color of a pigment. Learning the particular properties of a drying oil is part of the essential technical knowledge an oil painter should have. Remember that when an oil paint feels dry to the touch, it will still be drying under the surface for some time, which is why the principle of painting 'fat over lean' is so important in oil painting.
There are many other generic mediums that do not list their ingredients, only their effects, that are listed as Artists', Fat, Smooth, Lean, Colorless, Classic, etc. medium. But the following mediums are of at least partially known ingredients and are readily available on the market today.
TYPES OF PREMIXED MEDIUMS
Copal resin painting medium, and Flemish Siccative
Is a copal resin based quick drying medium which yields a paint film with an enameled-like appearance. Copal Resin, when it can be found, is today only used as an ingredient in mediums, and not in final varnishes so far as I know. Quality is non-uniform.
Oil of Spike Lavender
It can be used as a medium to give body to the color as well as a certain amount of bite, which improves adhesion to the lower layers. It can have the effect of either increasing or decreasing dry time, depending upon the other ingredients it is mixed with. If pure, it also works as a diluent, which was widely used in the middle ages. It dries more slowly than Turpentine, allowing the artist to work wet in wet.
Harlem Siccative Medium
Will speed the drying of oil colors and brightens the hues of colors. It is a form of drying medium used by academic painters of the late 19th century invented by a Mr. Durozier of France. Critics say that the original siccatif de Haarlem and siccatif de Courtrai both contains ingredients that turn dark, brittle and crack. Cobalt drier is recommended as the least harmful drier to add to paint films; little is needed. (Alkyd mediums may be a safer modern additive). Alkyd mediums like Liquin, are linseed oil modified alcohol-acid synthetic resin and has quickly becoming the favorite of artists to speed drying. Having linseed oil as its base, it is compatible with all oil colors, does not show the tendency to discolor or crack, and will not continue oxidation of the paint film beyond its proper drying level. It is best used with OMS as a thinning agent rather than turpentine. Historically, courtrai drier has darkened and cracked. Since the 1850s, cobalt drier has proven useful when added to glazing mediums containing stand oil, pure gum turpentine and damar varnish. Cobalt drier is said to be the least harmful natural drier to use in glazing mediums.
This gel medium is made with gum mastic and is used to recreate the effects put into practice by the Flemish masters, ie. Vermeer. Perfect for brilliant and precise detail work. Finished paintings have a luminescent, glossy appearance. This is most likely a form of Megilp, or mastic melted into boiled linseed oil and litharge or lead dryer such as Maroger.
Made of mastic and wax this medium will give the paint film a satin sheen. It will facilitate impasto work and superimpositions while regulating the drying process.
When mixed into oil colors this non-yellowing wax and resin mixture actually strengthens the paint film against shrinkage and cracking and seals out dirt, air and moisture. Wax mediums have been used throughout history.
DRYING OILS AND OLEORESINS
(preferred for mediums)
is a thicker processed form of linseed oil, with a slower drying time (about a week to be dry to the touch, though it'll remain tacky for some time). It's ideal for glazing (when mixed with a diluent or solvent such as turpentine) and produces a smooth, enamel-like finish without any visible brush marks
made from the seeds of the flax plant. It adds gloss and transparency to paints and is available in several forms. It dries very thoroughly, making it ideal for underpainting and initial layers in a painting. Refined linseed oil is a popular, all-purpose, pale to light yellow oil which dries within three to five days. It is used universally as a stand alone medium for oil paint or can be mixed with other ingredients to achieve a custom medium.
Cold Pressed Linseed Oil
dries slightly faster than refined linseed oil and is considered to be the best quality linseed oil. It is preferred as a vehicle for grinding pigments, though Alkali Refined Linseed is more popular due to its light color
Sun-bleached Linseed Oil
is created by exposing the oil to the sun but with the container's lid on, so no evaporation occurs. The result is an oil that has fewer tendencies to yellow.
Sun Thickened Linseed Oil
used the same as refined but is much thicker, and can darken light colored pigments. Good in impasto work. It is created by exposing the oil to the sun to create a thick, syrupy, somewhat bleached oil, with similar brushing qualities to stand oil. Pour some oil (about an inch) into a wide dish, cover it with a propped-up lid (i.e. to minimize debris getting in, but so that the air can flow through). Stir every day or so to prevent a skin from forming on the top. How long it takes for the oil to thicken will depend on how hot the climate is where you live. Test the thickness of the oil when it's cool, not when it's still hot from the day's sun. Pour it through a sieve or cloth to remove debris before you bottle the oil. As linseed oil has a tendency to yellow as it dries, avoid using it in whites, pale colors, and light blues (except in underpaintings or lower layers in an oil painting when painting wet on dry). Stand oil and sun-thickened oil yellows very little.
Poppy seed Oil
is a very pale oil, more transparent and less likely to yellow than linseed oil, so it is often used for whites, pale colors, and blues. It gives oil paint a consistency similar to soft butter. Poppy seed oil takes longer to dry than linseed oil, from five to seven days, making it ideal for working wet on wet. Because it dries slowly and less thoroughly, avoid using poppy seed oil in lower layers of a painting when working wet on dry and when applying paint thickly, as the paint will be liable to crack when it finally dries completely. Poppy seeds naturally contain about 50 per cent oil.
is a pale yellow-brown oil (when newly made it's a pale oil with a greenish tinge) that has a distinctive smell. As it's a thin oil, it's used to make oil paint more fluid. As it yellows less than linseed oil (but more than safflower oil) it's good for pale colors. Walnut oil dries in four or five days. It's an expensive oil and must be stored correctly otherwise it goes rancid (off). Walnuts naturally contain about 65 per cent oil. It is a good drying oil. Since it is said to yellow less than linseed, it may be good to mix with amber or copal to reduce yellowing that may occur with these hard resins.
Black Walnut Oil
dries through oxidation when exposed to air. Black oil does not have a tendency to yellow which makes it a highly reliable mixing oil. It may be worked in directly to color or in combination with turpentine. When mixed with Black Oil, colors develop a more durable, flexible paint film, allowing you to work the next day without disturbing lower paint layers. It was definitely a favorite of 15th Century painters. But can be difficult to find.
has the same characteristics as poppy seed oil, but dries a bit faster. It's made from safflower seeds. Not the one from the grocery stores!
also have similar characteristics to poppy seed oil. It's made from sunflower seeds. Not the one you get in the grocery stores!
are oils that have been heated and mixed with a dryer to create a faster-drying oil that gives a glossy finish. They tend to yellow and darken with age, so are best limited to lower layers in a painting and darker colors. If you're not sure what affect an oil is going to have, I suggest that you take the time to do a test rather than loose or damage a whole painting.
Venetian (or Venice) Turpentine
is in the oleoresin category. The judicious use of Venetian Turpentine will add luster and gloss to glazes. Extremely high percentages of oleoresin would make the paint film dangerously resoluble when cleaning.
Now that I have addressed the different oils and pre-made mediums that are available to most artist thru the retail environment, let’s get to the recipes, shall we!
SIMPLE RECIPES YOU CAN MAKE AT HOME
First, any one of these pre-made mediums can be used alone to get the stated appearances to your paintings as can many of the drying oils. But the reason for this article is for you to understand the preparation of custom, but simple mediums that are as similar to the ones made and presumed used by the Masters of Classical Oil Painting. That being said, the first two are pretty basic, and will give you good control when glazing methods are employed.
Damar varnish - 1 oz
Linseed oil (sun thickened) - 1 oz
Turpentine - 2 oz
Lavender oil - 3 drops per 1 oz (add just before using)
This is a good one for typical classical glazing techniques.
Sun-thickened oil - 2 oz
Damar varnish (resin) - 2 oz
Venice turpentine (balsam)- - 1 oz
Lavender oil - 3 drops per 1 oz (add just before using)
This recipe is a bit harder to learn to use, but it can give your paint a stained glass effect.
4 parts Italian maroger
2 parts beeswax
1 part English turp (add a second part for the bistre)
2 parts stand oil
1 part Venetian turp.
This medium gives your paint a translucent quality. The light can still transmit through it and bounce back from the underpainting and primer ground.
Venetian Glazing Medium
(one of my very favorites)
9 parts damar varnish (5 lb. cut)
9 parts turpentine
4 parts stand oil
2 parts Venice turpentine
For multiple layering add a little more stand oil to each layer.
This recipe will add gloss more safely than the use of a boiled oil hard resin medium. It will also give your paint a stained glass appearance and those beautiful diffuse highlights that Vermeer had!
All of these medium recipes can be thinned with rectified turpentine as needed, depending on what layer you are working on i.e. the verdaccio up through the final glaze layers.
All mediums should be mixed in quantities that can be used within a six month period. They should also be stored in glass jars sealed tightly with lids ( I use the kind you get in the grocery stores for canning vegetables or fruits) and kept in a cool dry area when not in use.
A Safety Note:
Remember all these materials can be harmful if used improperly. And Of course they should be kept safely away from children and pets!
A final note on technique:
When I use any medium in my painting I use it sparingly! You should never use more than a ratio of 20% medium to 80% paint. There are a number of methods classical artists have employed for using mediums in their painting, and I will discuss each one briefly.
The first is to “paint in the couch”. Which simply means to lay down a very thin layer of medium with your brush directly to you canvas on the area that you are going to paint in. This will make the paint slide on the canvas and blending is quite easy with this method. The concern in this method is in using too much medium, or overworking you paint.
The second method is to add the medium in small amounts directly to the paint pile on your easel. Also a good method, but can have the tendency to use too much medium and if you don’t premix your paint colors on your palette you can end up wasting a large amount of paint and medium, since it will dry quickly, (usually by the next day).
Last, and my preferred method, is to dip the end of my brush after it is loaded with my paint that I intend to apply, directly into the medium so that I have just enough of the medium to paint with each stroke. I keep a small glass bowl with a plastic sealing lid next to my palette for this purpose filled with a small amount of the medium I am going to work with. That way I do not contaminate the entire jar of mixed medium with oil paint.