The technical name for scratching into dry paint comes from the Italian, graffiare, which means to scratch. Sgraffito can be used to reveal white paper beneath a wash, and is a good way to create highlights, such as sunlight on water. It can also be used to scratch through one layer of color to reveal the layer beneath.
Paint can be scratched into using a variety of sharp implements. A craft knife is useful for scratching fine lines, as are sharpened brush handles, paper clips, and even your fingernails. For larger areas, sandpaper is very effective – both fine and course grades of sandpaper which create different results.
All of these techniques work better if the paint sits on the paper surface, rather than soaking into it to any depth, so try to avoid using sgraffito with staining colors such as alizarin crimson, viridian or phthalo blue. Needless to say, it is best to use sgraffito on heavy paper as it is less likely to tear and on top of dry washes.
The following are three (3) types of sgraffito:
1. Craft knife – To scratch fine lines, such as highlights on water, use the tip of a craft knife, pulling the blade sideways to avoid slicing into the paper and damaging it.
2. Fine sandpaper – Stroke the sandpaper over the surface of the dry paint. This is particularly effective on rough watercolor paper, as the paint remains in the troughs but is removed from the higher ridges.
3. Course sandpaper – Because the sand particles on course paper are bigger, the sgraffito lines are further apart. You can also fold the sandpaper to create a crisp edge, enabling you to scratch off sharp lines.
The two painting above illustrate the use of sgraffito. Click to enlarge these paintings to enable you to see the "scratches."
In my painting,
See Rock City, a craft knife was used to scratch in highlights in the wood of the barn and along the fence. A little sand paper was used to rough up the sky to add interest in the clouds.
In my painting,
Listen to the Ocean, medium sandpaper was used to scratch the surface of the exterior portions of the shell, a craft knife was used to scratch in the lines in the shell, and fine sandpaper was used to texturize the background around the shell to resemble sand.
Watercolor tip: You can also use sgraffito to remove small areas of paint to correct minor mistakes – for example, if you want to neaten an edge or the outline of an object. To do this, scrape gently, using the edge of the blade rather than the point, so that the paper is not torn and the scraped area remains flat.
Try this technique--sandpaper is not just for woodworking!