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Author: David_Rourke, Contributing Editor
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| The Terminator
It’s useful in thinking about light to borrow a term from astronomy: the terminator. On a planet illuminated by the sun, the terminator is the line that cuts across the planetary sphere, dividing day from night. On a human form with a single light source, the terminator is the boundary between light and shadow. If a sphere and its light source are the same distance from the observer, the terminator cuts the sphere in half (from the observer’s view point). If the light source is at an angle, the terminator cuts across the form in a curve that depends on the angle of the observer relative to the light source (you can observe this by holding a sphere or egg up to a light source and moving it around relative to your eye). The terminator on a sphere is always perpendicular (at right angles to) the light. On a more complex curved form, the terminator is as perpendicular to the light as the form will allow. That means that the terminator does not usually follow the form (as even some experienced artists depict it), but instead follows its own path, which on the body generally meanders. It takes careful observation to see and represent an accurate set of terminator lines on a rounded organic form. Sometimes, parts of the terminator are not clearly discernible on a complex form and are lost in the gradation from the reflected light to dark light (see below). The Light Zone Within the region of the form receiving direct light, there will be differences in how much light is reflected to the observer. Closest to the terminator, the light zone is least bright. This area is called the dark light. It gradually becomes lighter as the form turns toward the light and becomes the upper light, receiving relatively direct illumination. The brightest area is the highlight, where the light source is most directly reflected to the observer. Don’t expect the highlight to be at the center of the upper light; it falls where it falls. Shiny surfaces have highlights, while matte surfaces don’t. The body is semi-matte, which means that highlights are present, but less strong, and more diffuse, than on a shiny surface such as metal. It’s easy to paint highlights in a symbolic rather than representational manner, as discrete blobs of white paint, but that makes the form look like plastic. To make the highlight contribute to the illusion of organic form, it’s important to carefully observe its location, color, shape, and the manner in which is blends into the local form. The Shadow Zone There are two parts to the world of shadow: form shadow and cast shadow. The form shadow is simply the area that is not illuminated by the light source. Within the form shadow, the darkest zone is along the terminator. Moving away from the terminator is a lighter area of shadow—the reflected light, illuminated not by the light source directly but by light bouncing off objects and onto the form. It’s easy to overstate the brightness of reflected light; it’s normally much darker than the least illuminated area in the dark light, and sometimes hard to distinguish from the region around the terminator. Any form that blocks light can cast a shadow. A cast shadow is darker, with more discrete edges, the closer it is to the blocking form. Within the form there can also be small dark accents, where there is little or no light. It’s worth discussing the color of shadow for a moment. Some references describe all shadow as being cool. Others say that it is all warm, or cool in warm light and warm in cool light. But the color of shadow is more complex than such generalizations allow. The color of shadow is determined by the color of the form it falls on (the local color), the color of the original light source, and the color of the form it is being reflected from. On the body, the color of shadow often varies from warm to cool hues. Even if most of the reflected light from the environment is cool, some light is often reflected from one part of the body to another, resulting in regions of very warm tones. Some artists push the coolness of shadow color far beyond what they see, but that is a stylistic convention, not an accurate observation of how light interacts with form. |
| Now that I’ve described some principles and terminology, we can talk about painting. There are any number of perfectly good ways to construct an oil painting. This particular method involves observing the form and then directly creating as close a representation of the form as possible. It focuses on using the blending properties of oil paint to best effect. I’ll discuss a couple of issues related to color and materials, describe some useful exercises for learning to render form (the poster study and the rounding study), then describe the specific painting method.
Color For those not familiar with color terminology, let’s quickly review the three characteristics needed to describe color. [B]Hue[/B] is a specific color within the spectrum, such as yellowish-orange or greenish-blue. [B]Value[/B] is how dark or light something is. [B]Chroma[/B] is how intense a color is (in field of computer graphics, the characteristic is called saturation). You need to be able to look for the correct hue, value, and chroma on the form you are trying to represent, but also to see how those characteristics change, together and independently, as light washes across that form. You then need to be able to mix a specific hue, value, and chroma to represent what you see on the form (you can only represent what you see, not match it, since what you can mix with paint is not the same as what you see in front of you). One point about painting flesh: since most commercial pigments are high in chroma, it is easy to paint flesh as if it were that way as well. But if you look carefully, flesh is very low in chroma, closer in chroma to neutral gray than to the chroma of, say, cadmium red. When using photographic references, be aware that many film and digital camera systems artificially enhance chroma, because customers like brighter pictures. Real flesh tones are not nearly that bright. To get realistic flesh tones with bright tube colors, you will need to learn how to bring the chroma down, either by mixing with a neutral grey of the same value or by mixing in a complimentary color (one that is on the other side of the color wheel). Even some earth tones need to be neutralized to create realistic flesh tones. Painting Materials I personally have lots of opinions about painting materials, but they are not relevant to this discussion. I’m not going to comment about brands of paint, painting grounds, types of brushes, painting mediums, or other materials issues. You’ll need to figure those out for yourself, and really, they matter a lot less than learning to how see and then how to put the right spot of paint in the right place with the right shape. You can do that with almost any reasonable set of materials. Color Palette My teacher likes to have 30 or more different colors on his palette. I find that confusing and limit myself to 10 or 12. You should use however many tubes of paint you need to mix the colors that represent what you see. If you find it easier to use strong (high chroma) colors, then use them. Since, as noted above, flesh is usually low in chroma, you can also use less intense colors if you find those easier to mix with. I’ve been experimenting lately with a palette made up entirely of earth colors. That seems to work very well for me. First Exercise: Poster Study A poster study is for learning how to mix colors in the correct relationship to each other, without worrying about shape or detail. It consists of a series of flat fields of color. A poster study is best done with relatively large brushes (half inch brushes are good) on a small canvas or panel (5 by 7 inches or so). The idea is to observe an area—the center of the chest, for example—and think about what the overall average color is. How dark? How intense? What hue? Ignore highlights and small areas of shadow; we’re only concerned with the average tone for that region. It helps to throw your eyes out of focus or use peripheral vision in order to avoid detail. Mix the color you see and put down a blob of paint in about the right place, but don’t worry about rendering shape or form. Look at an adjacent area—the abdomen, for example. How does the overall value of the abdomen differ from that of the chest? Darker or lighter? How does the hue differ? The chroma? Mix that color and put it below the chest blob. This exercise is all about comparisons. Do the relationships on the canvas accurately represent the relationships you see in front of you? If not, scrape some paint away and start over. If so, move on to the next area... |
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| shapes of forms, gradations, or other factors. A good poster study is just a bunch of big flat blobs in the appropriate places, but those blobs accurately represent the hue, chroma, and value relationships that you see on the model.
The poster study is a useful exercise by itself as a learning tool. It can also be useful as a preparatory exercise before commencing a larger, more fully rendered painting. Once you’ve done a poster study, you can mix any of the colors in the final painting and know how they relate to each other. (If you’re just starting out and find the full-color poster study to be frustrating, you can start with a poster study in just shades of black and white; this is called a grisaille. It is easier to focus just on value differences while ignoring hue and chroma.) Second Exercise: Rounding Study To represent three dimensional organic form, a foundation skill is the ability to convincingly portray a sense of roundness. It’s harder than it might initially seem; some painters never get the hang of it. While the poster study is an exercise in flat color, the rounding study is an exercise in portraying the effects of light on rounded human forms. The rounding study is simpler than a fully developed painting in that you will ignore small sub-forms and see the figure as large rounded blobs. The head, for example, could be one undifferentiated egg shape. An arm can be a curved tube. The figure will come out looking rather like a possible artist’s mannequin (in fact, you can use one for this exercise if you like). |
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| In portraying each form in the rounding study, try to find and represent the terminator at the correct angle to the light (perpendicular, remember?). Paint the dark light, the upper light, and the highlight in the area receiving illumination. Paint the dark terminator region, the lighter reflected color, and any cast shadow you observe. To make the forms convincingly round (and you want them to really pop) you will need to blend the paint from one area to the next within each rounded form. It helps to put paint down with one brush and blend with a soft dry brush, which will need to be cleaned frequently. If you’re not used to blending, you’ll find that it takes practice.
(If you don’t have a model to work from, by the way, then you might want to paint a study of some eggs. If you can make them look round, you can make a figure look round.) Preparing to paint ONce you're comfortable with poster and rounding studies, it is much easier to paint a fully-rendered picture. There are two slightly different approaches that I’m going to describe. The standard approach taught by Ted Seth Jacobs is to work on a white ground, completing an initial block in, an underpainting, and then form painting. That method is nicely illustrated in the demonstration on Tony Ryder’s web site. The other approach is slightly less involved. The second method is to work on a toned ground, creating a block in, then going immediately to form painting. The second is illustrated in Tony Ryder’s article in the April 2006 issue of The Artist’s Magazine. Drawing Both methods start with an initial drawing. If you will be doing an underpainting, then leave the surface white. If you intend to proceed to form painting immediately, then tone the canvas first, brushing on any medium tone (such as an umber or sienna) mixed with solvent and then wipe it in with a cloth. The drawing can be done in charcoal or dark paint (don’t use graphite pencil as it may eventually strike through to the surface of the painting). If charcoal, then let any toning on the surface dry first. If paint, then use a fast-drying paint such as burnt umber, mixed with enough solvent to make it lean and easy to work with (but not watery). The initial drawing is in many ways the most important stage of painting. It’s worthwhile to take the time to get it right. I often regret that I didn’t spend more time with the drawing, wasting lots of time making later corrections. The drawing should contain plenty of information about the outline of the form and any landmarks within the form. It doesn’t need to be detailed. What it does need is correct proportion. Check the angle and distance from one point to another. Keep checking as you work, making changes (or even wiping out and starting over). Stay with the drawing until all of the angles and distances, from each landmark to every other landmark, is correct. If you used charcoal, there is no need to fix the drawing as it will simply be incorporated into the paint. Underpainting If you started with a white surface, then you will be doing an underpainting. This approach to underpainting is called the “wash in” or the “color wash.” It is done with the full range of colors on your palette, except white. In this way it is somewhat like watercolor. The paint should be somewhat thinned with solvent, but not to a watery consistency. (I generally add a drop of oil to keep the paint from becoming under-bound.) The purpose of the color wash is to create an intermediate layer that establishes the structure of the painting without getting too involved in detail. It is done in color, but since it is thin the darks can’t be quite as dark as in the finished painting. The color wash is used to kill the white of the surface so that value and chroma relationships can be more accurately judged in the form painting stage. It also helps to compensate for the transparency of some pigments. If you make a section too dark, it’s OK to wipe away paint with your finger or with a cloth or brush dipped in solvent. Don’t try to get a high level of detail with the underpainting; the idea is to establish the overall structure and then paint over it, so spending a lot of time on details that will later be covered would be a waste of time. If you are working on a toned surface without a full underpainting, then it can be a good idea to establish the dark areas of the form by quickily painting the large dark areas with a single base value, using a dark brown paint. Form painting If you’ve done an underpainting, then you can go immediately into form painting without having to wait for the paint to dry. It’s thin, so you’ll have no trouble painting over it with full-bodied paint. This is a direct painting method in which you attempt, section by section, to create the final, full-detail version of the painting. You’ll work with each section for as long as you need to make it look the way you want. The area of the section you choose should be whatever is comfortable for you to work on at a time. For a each section, this is the approach to follow. First, mix a color that represents the overall average of that area (just like the poster study). Make it a little dark, since it’s easier to work light paint into dark paint than the other way around. Lay in a base color for the area you’re concentrating on. Without worrying for now about detail, you’ll first work on developing a rounded base (just like the rounding study). Place the terminator, and work up the light zone and the dark zone. Get it looking round, with the right hue, saturation, and values. If you get it wrong, feel free to scrape away with a knife and start over. Once you have a convincingly rounded base, then look carefully at your subject. Where are the smaller forms, the subtle gradations, the interweavings from one form to another? Where does the terminator meander across the form? How sharp are the gradations in one area compared to another? Which edges are sharp and which are lost? Where are the highlights and the dark accents? These are the details that, carefully painted on top of an overall rounded base, will make the form look truly organic. Put these in carefully, with smaller brushes. Some people like to blend as they go, using a dry soft brush. Others like to lay the paint in and then blend as a final stage for the whole section. Either way, be aware that every small and large section of the body is a gradation of value, so no area should be a simple flat tone (although sometimes the gradation is very gradual and subtle). This method therefore requires a lot of bending. Use the blending brush to pull the light from one section into the dark of another section, or vice versa. Clean the brush after every stroke or two. Keep comparing your painting with the model. You’ll find that lots of corrections need to be made as you go. Refine each small detail, restating edges where needed, until the section you’re working on is right. Then move on to the next section, using the same approach. If you need to stop for the day, then blur the edges of uncompleted sections so that it will be easier to work them up when you start again. Although this is basically a direct painting method, don’t be afraid to go back and fix some area of dried paint that you didn’t get quite right the first time. THAT’S IT This method takes careful thought and lots of practice, but can produce stunning results. I hope I’ve explained it in a way that is understandable and useful. |
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| B i o g r a p h y | |
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David Rourke paints in oil and egg tempera. He is interested in Renaissance and Old Master painting techniques and materials. Currently, he studies figure drawing and painting with Dennis Cheaney at the New England Realist Art Center. |
| E-Mail: turlogh@fastmail.fm Web Site: http://www.rourkevisualart.com | |
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