The ART of THICK PAINT

9. The Structure of a Painting

When I started my first painting class I didn't even know how painters put paint on the canvas. I was told to do a preliminary painting. This meant a thin monochromatic underpainting with a lot of turpentine. But I never was told why to keep it monochromatic and why it needed to be thin. It was always implied that it was the best practice. It took me several years to understand that paint (oil paint especially) has a very logical order as to what consistency should be painted and at what time. Other mediums are less exacting (acrylics for example) but the aesthetic reason for painting from thin to thick persist even with acrylics.

If you read about painting much you will stumble across the expression fat over lean. In most cases what is meant by this phrase is that in order for the paint film to dry structurally correct (without future cracking) the paint layers must be lean, meaning having less oil medium, on the bottommost layer. Subsequent layers can then be fatter, meaning they can have successively more oil medium as you layer on paint. If you violate this dictum you run the risk of having a structurally poor painting that will crack over time.

However what is mentioned less often is that this dictum also describes the only way that paint can be placed onto a canvas with any sense of textural harmony and aesthetic integrity. In other words fat over lean is a structural as well as an aesthetic necessity. If you're going to add a lot of texture to your paint you either have to paint it all in one session, alla prima, or you have to do so layer by layer gradually building up the texture.

Let me describe how most painters apply paint onto the canvas: Initially a very thin layer of oil paint is washed onto the canvas. This wash is usually a monochromatic mixture of warm paint such as burnt sienna. We will discuss more why this wash is usually a warm color at a later point. The brush is loaded with thicker applications of the same color and the painter draws into this wet layer almost like a watercolor painting. The layer is not so wet that the turpentine medium dilutes the brush marks. The marks have to stay in place for the drawing to emerge. Some artists wipe into this wash with a rag to remove some paint in the lighter areas. Texturally this application of paint will dry very thin, almost like staining the canvas. This layer is very lean, meaning it has very little oil medium. This layer is allowed to dry and when dry it will look like a monochromatic version of the final painting with darks and lights indicted but with little detail (since the detail would be covered with subsequent applications of paint).

The next stage for most painters is simply matching values of hue and placing them over this monochromatic underpainting. In other words, let's say you had a dark distant mountain indicated in your monochromatic underpainting, which is burnt sienna. This first application of paint is a very thin wash of very dark paint. So the painter mixes up a blue that is the same value as the burnt sienna underpainting and the painter paints this blue over the top of the underpainting. So at this stage it is a matter of matching value to value on the underpainting. Most painters suggest that leaving a bit of this burnt sienna underpainting adds a bit of scintillating color especially in greens. It is one way to get some cheap field effects into your painting, but remember that the effect will be accidental. Burnt sienna, or any monochromatic underpainting, won't be the prefect field effect for every color (more on field effects later). At this stage texture can be built up a much as you like, especially since many painters will be essentially done at this stage. This layer is allowed to dry.

Typically the next layer of paint will be a flurry of dry brush strokes and wet-into-dry applications of paint. A variety of brushes can be used including palette knives, riggers (for very thin marks such as telephone lines), as well as a host of flats to give light scumbles of paint across broad areas. This is a perfectly acceptable way to paint and many artists use the method quite admirably.

But for me it doesn't provide enough flexibility to add the painting effects I felt compelled to include in my paintings. Essentially I wanted to paint in a way that looked like it was painted alla prima but allowed for many applications of paint. Painting the perfect painting in one session required too much virtuosity.

So I added two commonly accepted methods, oiling up the canvas, and scraping the canvas at various stages. The trick is that each successive layer of oil with which I oil up the canvas needs to get progressively thicker to allow for progressively thicker applications of paint. I will elaborate more about oiling up in a later chapter.

So here is the new process with these two aspects added: do a monochromatic underpainting as per the traditional method (I usually use Red Iron Oxide or Burnt Sienna). I then paint in what I call a full-color, full value underpainting. In this phase I try to add all of the right colors and values and lighting effects (reflected light, and so on). I keep this layer extremely thin and I allow the red iron oxide underpainting to show through in places. I want this layer of the painting to be designed to look right at a further distance, say 20 to 25 feet. It's not important for the texture, the field effects, or precision blending to be in this stage of the painting. The sky, for example, can be very brushy and flat as it shifts from one color to the next. The important thing is that the values be correct. The exact hues can be approximate.

Since transitions and brush work are not important at this phase you can paint as many sessions as you need to get this phase correct. If the sky is too light you can glaze it so it is the right color and value. If a mountain is too dark you can scumble a lighter blue over the top until the color ad value reads correctly from a distance. This relieves you from having to paint a perfectly glazed and rendered painting as you work out the important detail of value, saturation, and hue. You can quickly simplify a foreground by adding a wash of brown or green. Shadows can be enhanced by glazing or scumbling.

Surface virtuosity is completely disregarded at this phase. In fact all texture and brushstrokes will be either scraped away or obliterated by future applications of paint. So keep the paint thin as well as any medium you glaze or stumble with (at this phase I will use either pure Gamsol or Gamblin's Neo Megilp). Focus on the big picture by stepping away from your canvas frequently, at least far enough away that you can't see surface imperfections.

This is a good time to take a break or start a new painting. You can turn the canvas to the wall so you can come back to the painting with a fresh eye when your enthusiasm rises enough to push the painting forward again. The point is to press forward only when you have enough energy to complete each phase of the project successfully.

The next phase can be repeated as many times as necessary but the point is to try to add paint as freshly and as with much virtuosity as possible. If I have accumulated any texture in the last phase I scrape it with a ceramic loop tool that has been sharpened. I have several of these tools but my favorite has an egg-shaped loop about 4 inches across. I used a sharpening stone and a stropping belt to sharpen the edge. You can sharpen it as much as you feel comfortable with but I suggest getting it a fairly sharp because you will often need to remove thick clumps of paint. There are several commercially paint scraping knives available but have not found them to be very useful.

Once you have made sure the surface of the canvas is quite flat I start mixing up patches of paint that match the hues and values on the canvas. This is a little bit more intimidating phase so I have a regimen I go through to give me more confidence. I typically mixed up my sky colors using variations of blue that are warm, cool, and neutral. If the sky shifts in value as it arcs (as nearly all skies do) I will mix up six paint patches, one light set and another set that is darker.