Handout #3: Underpainting method 2 - Rub-out or Subtractive method
Materials: canvas panel, oil paint (burnt sienna, raw umber) odorless mineral spirits (OMS), rag, gloves, spray fixative, charcoal, #2 pencil
1. Sketch out your composition loosely with vine charcoal on canvas, then re-draw with pencil. Wipe away charcoal with a dry rag or paper towel. Apply fixative and let dry a few minutes before proceeding.
2. While the spray-fix dries, thin burnt sienna paint with odorless mineral spirits—squeeze out an inch or so onto your palette. Gradually add small amounts of OMS and work with a palette knife. Paint should be fairly thin but not runny--something like ketchup consistency.
3. Using a large brush, work the paint over your canvas. You should see a slight sheen to the damp paint, but not a wet, shiny surface. This first layer is called an imprimatura. (Any color paint may be used for this layer--earth tones usually are harmonious for landscape colors, so I've recommended that. But feel free to explore--reddish purple can be gorgeous under greens, for example.)
4. Wipe the excess paint off the canvas lightly with a rag* to leave an even tone. Wipe a small area with a clean part of your rag to test the paint film. It should wipe away the paint and leave a pale tint on the canvas. **
5. Instead of applying white paint to create an underpainting as we did in the first method, we'll establish lighter values by removing paint. Wear vinyl gloves and use a rag* wrapped around your finger to remove paint from the lighter area. Begin with a dry rag, switching to a light dip in OMS to reveal the lightest values. Intensify some of the shadow areas with a brush and undiluted paint in the color you're using. To remove small areas, you may wrap your rag around the end of a paint brush or a pencil with an eraser. You can achieve a high level of detail using this technique and actually create a finished work (see Mark Tansey's paintings, for example) or simply establish an underpainting value structure to on which to build a finished painting.
6. Let the canvas dry a few days before applying color. Color may be glazed over this underpainting, then detailed with lean transparent paint, and modified where needed with scumbled opaque paint. Another way to work is to paint opaque colors over the underpainting, letting some of the imprimatura show through your colors. Glazes to enrich or alter these colors may be used after the opaque color is thoroughly dry.
*We don't use paper towel, which will tear up and leave bits on your canvas.
** Canvas panels are usually very good for this technique because their primer is not very absorbent. If paint on other types of canvas doesn't wipe away easily, it may be that the gesso on your canvas is too absorbent. A dryish look when you apply the paint is another indicator of this condition. It's a good idea to test a small scrap of your canvas to determine how yours will perform. A solution to the problem is to apply a coat of acrylic medium--and it's probably best to do this to any canvas you're unfamiliar with to avoid the problem altogether. (If you've jumped in without testing first and find you have one of these absorbent primers: acrylic medium can't be applied over oil paint, but you can allow the imprimatura to dry and use this canvas for a different paint technique--underpainting with white paint, for example. Different gesso brands have different levels of absorbency—each has its use.)
1. Sketch out your composition loosely with vine charcoal on canvas, then re-draw with pencil. Wipe away charcoal with a dry rag or paper towel. Apply fixative and let dry a few minutes before proceeding.
2. While the spray-fix dries, thin burnt sienna paint with odorless mineral spirits—squeeze out an inch or so onto your palette. Gradually add small amounts of OMS and work with a palette knife. Paint should be fairly thin but not runny--something like ketchup consistency.
3. Using a large brush, work the paint over your canvas. You should see a slight sheen to the damp paint, but not a wet, shiny surface. This first layer is called an imprimatura. (Any color paint may be used for this layer--earth tones usually are harmonious for landscape colors, so I've recommended that. But feel free to explore--reddish purple can be gorgeous under greens, for example.)
4. Wipe the excess paint off the canvas lightly with a rag* to leave an even tone. Wipe a small area with a clean part of your rag to test the paint film. It should wipe away the paint and leave a pale tint on the canvas. **
5. Instead of applying white paint to create an underpainting as we did in the first method, we'll establish lighter values by removing paint. Wear vinyl gloves and use a rag* wrapped around your finger to remove paint from the lighter area. Begin with a dry rag, switching to a light dip in OMS to reveal the lightest values. Intensify some of the shadow areas with a brush and undiluted paint in the color you're using. To remove small areas, you may wrap your rag around the end of a paint brush or a pencil with an eraser. You can achieve a high level of detail using this technique and actually create a finished work (see Mark Tansey's paintings, for example) or simply establish an underpainting value structure to on which to build a finished painting.
6. Let the canvas dry a few days before applying color. Color may be glazed over this underpainting, then detailed with lean transparent paint, and modified where needed with scumbled opaque paint. Another way to work is to paint opaque colors over the underpainting, letting some of the imprimatura show through your colors. Glazes to enrich or alter these colors may be used after the opaque color is thoroughly dry.
*We don't use paper towel, which will tear up and leave bits on your canvas.
** Canvas panels are usually very good for this technique because their primer is not very absorbent. If paint on other types of canvas doesn't wipe away easily, it may be that the gesso on your canvas is too absorbent. A dryish look when you apply the paint is another indicator of this condition. It's a good idea to test a small scrap of your canvas to determine how yours will perform. A solution to the problem is to apply a coat of acrylic medium--and it's probably best to do this to any canvas you're unfamiliar with to avoid the problem altogether. (If you've jumped in without testing first and find you have one of these absorbent primers: acrylic medium can't be applied over oil paint, but you can allow the imprimatura to dry and use this canvas for a different paint technique--underpainting with white paint, for example. Different gesso brands have different levels of absorbency—each has its use.)
