Q: How do I care for Galkyd so that it does not dry in the bottle?
A: Galkyd is such a vigorous dryer that if it loses enough solvent it will try to dry in the bottle. First it merely skins over. Then if it goes further, it turns to a gel-like substance. Except for the 2 fl oz jar, we package Galkyd in glass bottles from the factory. Storing Galkyd in a plastic bottle accelerates this process since some air actually passes through the plastic.
To keep Galkyds from drying in the bottles:
If the Galkyd has skinned over you can still mix solvent (Gamsol or other Odorless Mineral Spirits (OMS) works fine) into the medium and save it. If it has turned to gel, there is nothing you can do, the drying has gone too far.
Galkyd is made from alkyd resin, the polymerized oil of the 20th century. To polymerize an oil, the molecules of oil are connected in chains (polymers) through a heating or oxidation process. This is the initial stage of the drying process, so polymerized oils dry faster. Sun thickening was the method for polymerized oil from the 18th century and stand oil, which is linseed that has been heated without exposing it to oxygen, was from the 19th century. Polymerized oils have higher viscosity (they are thicker) and are faster dying than linseed, poppy or sunflower oils.
Alkyd resin differs from stand oil in that it is so highly polymerized that there is solvent in the fluid to keep the chains of molecules apart. When the medium loses solvent, the polymers move closer together, actually touch, link up, and start the final drying process.
Q: Are the working properties of Galkyd like traditional painting mediums?
A: Most alkyd resin painting mediums are ready to use when you buy them. Gamblin's Galkyd is formulated to work more like a damar medium containing stand oil. Galkyd Lite is formulated to work more like a damar medium containing refined linseed oil. Galkyds can be made into glazing mediums by adding OMS. Mix only enough glazing medium for a single painting session by adding OMS to Galkyd. Oil colors mixed with alkyd resin painting medium result in tough, flexible and elastic paint films. Alkyd mediums may also interest painters who want to bond dry pigments, sand or various other materials to their paintings.
Q: Why use Galkyd instead of a painting medium made with damar resin and turpentine?
A: Galkyd is made from alkyd resin. Alkyd resin, first manufactured in the early 1930's, is produced by a reaction of natural oil with a polyfunctional alcohol and polybasic acid. Alkyd resin as a binder cannot hold the high pigment load of linseed oil. So alkyd has been formulated for use in artists' materials, most successfully, as an oil painting medium. Alkyd resin painting mediums are now more popular as glazing mediums and general painting mediums because they are made with milder solvents and really do speed the drying time of oil colors. Thin layers of oil colors mixed with alkyd resin painting medium will dry in 24 hours.
Turpentine is the only part of oil painting material that is toxic. It is the only solvent commonly available to painters that is absorbed through healthy unbroken skin. Damar resin must be dissolved in turpentine. By using Galkyd, painters will be able to use the mildest form of solvent, odorless mineral spirits. Mediums made with damar varnish darken significantly with age.
Q: How can I make Galkyds more matte?
A: To make Galkyd or Galkyd Lite more matte, dissolve one teaspoon of Gamblin Cold Wax in enough odorless mineral spirits to dissolve the wax completely (approximately 2 fl oz or 1/4 cup). This is the matting agent. Add 1/4 matting agent to 3/4 Galkyd to make a more matte finish. To make a lighter glazing medium, add OMS.
Q: How can I slow down the drying time of Galkyds?
A: Add approximately 10% by volume refined linseed oil or poppy oil. The added oil will increase the open time and slow down the drying time. Be careful not to add too much more oil because it may increase the tendency of the oil paint film to wrinkle (alligator).
Q: Is it OK to thin my paint with solvent to begin my painting?
A: If you use solvent to separate the oil molecules too far (Rothko's technique), then they cannot cross-link by connecting to each other and form a paint layer. Instead of making an oil painting, the result is like a pastel painting. Any movement of the canvas or air moving across the surface or simply the effects of gravity will cause the particles to dust off slowly until there is no painting left.
Thinning paint with solvent is different than using solvent to create very fluid paints. To make very fluid paints, consider adding a binder, like Galkyd, to the solvent.
An oil painting gets its strength from the oil binder that has cross-linked into a paint layer or "film". To dry into a tough, flexible film, the oil must be a continuous surface. At the end of the processdecades later, if not hundreds of years, every molecule of oil will be connected to every other, both holding the layer to the canvas and firmly locking the pigment particles in the paint film. Alkyd resin painting mediums remain more flexible over time and Galkyd will not yellow or darken with age.