So I ran upstairs into the kitchen and grabbed my motorized knife grinder and honed the edges of the knife to a sharpness that would cut paper, and then ran into my studio to try scraping some dried impasto off a painting in progress. (Of course, my woodworking chore was at this point completely forgotten — a thing which would irritate my wife later in the day.) The difference was amazing. My newly sharpened palette knife sliced right through any crusty paint like a knife going through butter, and the flat surface left behind was perfect for new paint. Sweet! Gone was the underlying texture that interrupted the gestural motion of my finishing strokes. Gone were the annoying flickering highlights that often destroyed the depths of my darks. And gone was the warp and weave of the canvas when I wanted it, since my knife could now level the paint film to exactly the depth of the cloth.
- Palette knives with drop handles are best because you can lay the blade flat against the canvas or panel and still keep your fingers above the painting. (see photo to the right) Flat palette knives, which are more like spatulas, don’t permit you to lay the blade along the surface without dragging your fingertips through the paint.
- Once you sharpen the palette knife it becomes a true knife. This is easy to forget as you work. You can cut yourself badly and I have done so. So be careful. Be aware that when you wipe the knife with a rag its edge can cut through the rag and into your hand. (Which is exactly what I did.)
- The easiest way to sharpen a palette knife is with the aid of a motorized grinder, such as a Magic Chef Knife sharpener, or something similar. I only need to draw the knife through my sharpener once or twice on the right side of the slot to get a fresh edge, and I don’t have to do that often since the edge seems to hold a long time. For anyone who don’t own or have access to a knife grinder, let a professional do it for you. Trust me, that edge will last quite a while.
- When scraping the crusty paint, lay the bottom of blade flat against the surface and not at an angle. Angles encourage digging and lifting and most of the time you won’t want that. As you slice, a slight sawing motion may help with the cut. But don’t over do it. You are not trying to dismember an elk. Some care is helpful
- I recommend making several light passes over trying to scrape everything off at once. This is true for woodworking as well. More of a shave than a slice.
- Scraping down a drier area of a painting still in progress will drop flecks into any wet areas below. You can avoid this by flipping the painting around, or by tipping the top of the canvas towards you so the scrapings drop straight away from the surface.
- And finally, remember those flecks are still paint. Don’t leave them lying about the studio. If there is lead white, or cadmium, or other potentially harmful pigments in those scrapings, then clean it up. I use damp paper towels to wipe the bits and pieces up. The dampness prevent any of the tiny flecks from being thrown up to where they might be inhaled.