1. OIL MEDIUMS:
As mature artists, so does their palette of color and their subject matter. What they add to their paint to modify the look, feel and paintability, though, may not have been examined as thoroughly. The “mediums” to add to oil paint are numerous and are often misunderstood. With the following, we will start to examine these products, beginning with oils. In a future newsletter we will look at solvents, driers and other oil paint additives.
Cold Pressed Linseed Oil – Pale yellow in color, increases gloss and transparency. Reduces brush marks. Produces a flexible film.
Refined or Polymerized Linseed Oil – Hot (steam) pressed oil further refined for artist’s use. Increases gloss and transparency. Historically considered inferior to cold pressed oil as heat pressing reduces resistance to embrittlement, though modern technologies have minimized this fault. Wide range of colors.
Stand Linseed Oil – Oil heated until it changes at the molecular level. Heavy, viscous. Yellows less with age than other oils. Dries to a smooth, elastic, enamel like finish. Lighter than other oils.
Sun Bleached – Refined Linseed Oil – Polymerized, oxidized and bleached by the sun or modern techniques that duplicate the sun’s influence. Faster drying than refined and lighter in color.
Poppy Oil – Natural pale or colorless oil that yellows less than linseed oils. Slow drying rate. Weaker film than linseed oils which can promote cracking with aging. Best used in direct “alla prima” painting.
Walnut Oil – Non-yellowing oil. Dries at a rate similar to linseed oil. There is much debate over the durability of the walnut oil film. Although there is documentation that walnut and linseed oils were used interchangeably through history, many modern chemists regard walnut oil as inferior. Contemporary technology has suggested, however, that the findings of the late 19th and early 20th century chemists were flawed.
Black Oil – Pure walnut oil combined with lead and a fast drying oil. Used by the old masters. Darkens paint color. Modern use for antiquing purposes.
Damar Medium, also spelled dammar, traditionally is a mixture of Stand oil, Damar and Pure Gum Turpentine. Damar resin is extracted from fir trees found in Indonesia and Malaysia. In making the medium, damar crystals are commonly dissolved in Gum Turpentine. Wet Paint carries dammar crystals and a pre-mixed dammar medium that uses citrus thinner instead of turpentine.
Maroger medium is a modified oil-resin mix which imparts luster and a unique brush-ability to tube oil paint. The medium is a mixture of mastic (tree resin) and black oil (heated or polymerized walnut oil) and litharge (lead dryer). LeFranc Oil (distributed by W&N) produces two specific mixtures based on older European formulas. Flemish oil medium inparts a glossy enamel-like finish to the surface and is productive for glazing; while Venetian medium is similar to Flemish in composition but differs with the additional presence of bees wax which reduces the gloss to a satiny luster. We also carry maroger in a tube from Sennelier which is significantly more expensive and is more paste-like. It produces a satin finish when thinned with turpentine. All oil-resin mixtures such as maroger need to be thinned with turpentine. Oil spirits will not properly reduce these formulas. It is important to mention that all of these mediums have a significant amount of lead in them and are considered toxic. Also, maroger medium has been shown to darken the paint film over time making, its permanence less than ideal.
COPAL PAINTING MEDIUM
Traditional copal painting medium is made from fossilized resins that are exuded from living plants and mixed with linseed oil. It should only be used in small amounts. It will speed drying time, improve flow, and increase gloss.
VENETIAN TURPENTINE RESIN
Venetian Turpentine Resin is a viscous natural balsam made by Schmincke. It is tapped from European larch trees and therefore is sometimes referred to as larch turpentine. It is good additive because it contributes to the stability of the film. It is more flexible than other resins and is relatively non-yellowing. Use sparingly.
Alkyd Resins are a synthetic resin for oil paints. Made by combining an alcohol/acid resin with soy oil, these resins make good binders that are durable and dry fast. When used as a binder or medium alkyds are for the most part clear; some yellowing has been reported. Winsor & Newton makes a line of paint using alkyd resin as the binder (Griffin). These paints or mediums can be used interchangeably with other paints and mediums.
Neo Megilp is made with an Alkyd resin base. It is Gamblin’s answer to toxic black oil. Unlike Black oil, Neo Megilp will dry very fast without becoming brittle or darkening. It is a great glazing medium.
Galkyd is made from Alkyd resin by Gamblin. It dries very fast and is great for glazing. This medium can be used as an alterative to traditional Stand oil / Dammar / Turpentine painting medium. There are different varieties of Galkyds highlighted below. Over all it will add gloss and clarity of color to a painting. Similar effects can be had using Stand Oil.
- Galkyd: fast drying; high cohesion; great leveling properties
- Galkyd Lite: low viscosity; fast drying-medium cohesion; will show brush strokes
- Galkyd SD: slow drying; low cohesion; great level properties
WALNUT ALKYD MEDIUM
Walnut Alkyd medium is made from Alkyd resin and Walnut Oil. It is for accelerating drying time and enhances in adhesion between layers. This medium is great for glazing. Like many glazing mediums it dries glossy. Because it is Walnut Alkyd it is non-toxic and will not yellow like other mediums.
Liquin is another modified resin used for glazing, made by Winsor & Newton. Dries very fast. Improves the flow and transparency of the paint.
Wingel is another modified resin made by Winsor & Newton. This comes in a tube form, but it is not an impasto medium. It is know as a thrixotropic gel because as it is mixed it liquefies and then re-gels. Over all it is quick drying, improves flow, transparency, and dries glossy.
Impasto Mediums are mediums that will help to strengthen and extend without thinning the paint. Another benefit is that thick strokes of paint will dry much faster and more evenly with the aid of a medium. In fact the thick rough stokes may not hold up without the added strength of a medium.
Oleopasto is Winsor & Newton is oil modified alkyd resin, impasto medium. Dries fast, extends colors, and is resistant to yellowing. Will add gloss to a painting.
Res-n-gel is an alkyd made by Weber. Non- toxic, non-yellowing, glossy, and quick drying.
Galkyd Gel is Gamblin’s impasto medium. It is quick drying, full-bodied and glossy.
ZEC is made by Grumbacher they use stand oil and natural resins for their medium. It is full-bodied, and speeds drying time.
SENNELIER IMPASTO MEDIUM
Sennelier impasto medium is an emulsion of water in oil made possible by the incorporation of China Clay, along with safflower and stand oil, egg yolk, synthetic resins, gum Arabic and several types of drier including lead. Thickens oil paints for impasto and relief techniques that are usually inadvisable with oil paint. It can be applied directly to the support, left to dry and then painted over with oil colors. Mixed directly with oil colors (in any proportion) it produces a creamy paste of a slightly lighter hue depending on the amount used. It can be thinned with turpentine, mineral spirits or water. Adding turpentine makes colors more matte. Dry time: 1mm approximately two weeks, ¼” may take a few months.
COLD WAX MEDIUM
Cold Wax Medium can be used as an impasto and a glazing medium. It has a matte finish, and can also be used as a protective coating. Wet Paint carries two types of cold wax mediums. Gamblin’s cold wax is made from bee wax and mineral spirits (Gamsol), while Dorlands is made from a compound of waxes and resins. It should be used in limited amounts on inflexible surfaces in order wax to prevent cracking.
Driers, as the name implies, help oil paint to dry faster. They are traditionally referred to as siccatives. Driers work by accelating the rate at which oil molecules absorb oxygen. Traditional siccatives use lead, manganese or cobalt metals to promote oxidation whereas alkyd resin is used in modern driers. Excessive use of drier can weaken the paint film and cause discoloration.
Japan drier is Alkyd resin, Mineral Spirits, Aromatic 50 Solvent, and Cobalt Naphthenate made by Grumbacher. Speeds drying, improves gloss. Add directly to color in small amounts. Color should not be thinned beyond a soft free brushing consistency.
Cobalt drier is made from Aliphatic Petroleum Distillate; D-Limonene and Cobalt Tallete by Grumbacher. Speeds drying. Add small amount to color, mix well, test before using.
1. Professional Oil Paints