Friday, May 27, 2016

Paint Basics

Whenever I think about something, it's important to begin with the essentials. So with this post I'm trying to begin at a very basic level. No discussion of paint brands or critiques of various ways of painting. This post is simply about paint--any kind--and what it's made of.

Paint is a preparation of pigment in liquid, intended for application to a surface or an object. Paint may be functional--barn paint--or decorative--fine art. Artist paint these days is sold in quite a few different forms including paint made with oil, acrylic, casein, gouache, egg tempera, or transparent watercolor. The last five types of paint are water-based or water-soluble, with certain additions. Some also call pastel pictures "paintings" and classify pastel as a genre of painting. Others classify pastel images as colored drawings. In this post I'm speaking only of liquid paint; in general paint is liquid and applied variously with brushes, knives, or other implements.

Besides pigment and liquid (vehicle, composed of binder and solvent), paint may contain any number of other materials, depending on the maker and the intended market. Although properly speaking, in oil paint linseed oil is the binder I'm going to call it the vehicle (which is the binder diluted with something) for the purposes of this post. Manufactured oil paint commonly has various additions--preservatives, stabilizers, filler, substances that improve the flow of the paint, and others. Generally speaking, the best paint is thought to be mostly (or only) pigment suspended in a vehicle, with the caveat that sometimes the "best" paint is a compromise. Certainly, to get the most from a color, the painter craves very pigment-rich paint, a heavy pigment load. But sometimes there's also a need to compromise between purity and additions that improve the paint's handling characteristics. Professional grades of oil paint may be labelled "pure pigment" but even then, certain pigments require help to be made into paint to avoid issues like stringiness or near-insolubility or other problems. Also, professional grade paint is often intentionally produced "short" of oil, which allows the painter to alter the consistency and handling of the paint to suit their personal preferences by addition of more oil or the use of mediums.

Gary Hoff: "Primaries," 2006
Paint may be "permanent," meaning that depending on exposure, the paint can last longer than most people do, and also that the pigment is stable and won't fade or shift in color. Impermanent paints may also go chalky or crackle into chips and pull away from the surface, especially those exposed to sun and weather on outside walls. Indoors, paint suffers considerably less, so that in traditional oil painting, layers of color can be put down and last hundreds of years. Casein paint dries and lasts well too, possibly as long as oils. Watercolor is another matter since watercolor paintings can be easily damaged by humidity or water. Gouache, an opaque watercolor that was once the preferred medium of illustrators, can also be damaged by exposure to humidity or water, but the colors available today are light-fast. Acrylic paint has only been around for about eight decades, a brief period in comparison to other kinds of paint, and so hasn't yet shown the longevity of other paint. Once it dries, acrylic paint seems nearly bulletproof, and is more flexible than oil paint layers, but whether that flexibility remains over many more decades remains to be determined. A neat advantage of acrylic is it's ability to be thinned dramatically and employed in transparent layers like watercolor, since after it dries it isn't bothered by water exposure.

The binder in oil paint is one of several natural oils termed "drying oils" that are derived from various vegetable sources. Oils that dry transform from a liquid into a solid, flexible, tough, durable film. If there is pigment (color) suspended in the oil, we call it paint. Drying oils take up oxygen from the air to form a natural polymer, hence the tough film. Drying oils include linseed, walnut and other nut oils, and certain treated safflower oils. Poppyseed oil is sometimes used as a paint vehicle and said to be a drying oil, but those I know and trust who have used it say it never really dries and remains gummy seemingly forever. It needs the assistance of a chemical dryer. I've no personal experience with it.

If you look at linseed oil in the bottle, it seems quite yellow to use in paintings, yet when mixed with pigment, the predominant effect is the color of the pigment, not the liquid. And when oil paint dries it seems to take on more brilliance, especially when the painting is exposed to sunlight. So the slight yellow color of linseed oil isn't a problem. Nut oils also have a trifle of coloration but again that slight tinge doesn't change the normal color of pigments or dull paint made with walnut oil. I've no experience with any other nut oils. Acrylic vehicles are generally clear, and of course the other kinds of paint mentioned above are all thinned with water, which serves as vehicle and thinner in one.

Gary Hoff: "Secondaries," 2006
With regard to buying, my experience has been that you should buy the very best quality paint (and other materials as well) that you can afford. Student grade paint (cheaper) contains less pigment than artist grade or professional grade tube paint and more inert (not pigmented) material, to make a less expensive paint. The problem is that fillers alter the mixing quality of various colors and sometimes the handling quality of the paint paste as well. It is better to paint with a limited palette of top-quality paint. And top quality paint can actually last longer since the pigment load allows better color mixing with less paint. When exploring new paint manufacturers, I've often bought only a few tubes at a time--say, a tube of raw umber, a white (I prefer lead white), and maybe yellow ochre. Earth colors can say a great deal about the paint maker. For example, ochres are brighter alone and in mixes if ground relatively coarse. That means the paint will feel a bit gritty if mulled properly. Some colors--alizarin crimson for example--are best when rather waxy. And all good paint should mix well. It doesn't cost much to try two or three tubes because if you're painting much at all, you'll use a small tube of these colors pretty fast.

Good paint comes from companies like Golden (acrylics and oils), Gamblin, Williamsburg, and Vasari, to name a few. The paint will cost more, and some of these companies only sell online or in limited locations. But the paint is worth the price, and the results have always pleased me.

What about those really poisonous paints that some people still use, like lead white or vermilion, or others? Well, most are still made because artist paint has an exception to the ban imposed on some pigments formerly in general use. Lead white is an example. You can't buy lead white in Europe, I'm told, but it's available here from a number of manufacturers. It's not a deadly poison, in the sense that you aren't killed by small doses. Further, lead carbonate, the main lead pigment, isn't absorbed well by the skin, at all. If you use lead, you should wash hands and maintain a clean studio, but beyond that, you're not in any danger. Vermilion is a bit different--it's a mercury sulfide compound and is more poisonous than lead. In the past, it was a great color for adding the flush of normal skin coloration to portraits, and so on. However, there's little reason these days to use natural vermilion--made by grinding a mineral called cinnabar--because contemporary substitutes are less toxic. Cadmium red is a good stand-in, but in any event is still toxic, just in much higher doses. Mercury causes nerve damage; cadmium causes cancer. The main solution in using paint (and other materials) that has toxic properties is simple cleanliness. Keep paint off skin, keep hands clean, don't put paint in one's mouth, ventilate the studio. Simple measures but important ones.
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