Canvas white pigment and calcium carbonate is rather brittle and susceptible to cracking. As lead-based paint is poisonous, care has to be taken in using it. Various alternative and more flexible canvas primers are commercially available, the most popular being a synthetic latex paint composed of titanium dioxide and calcium carbonate, bound with a thermo-plastic emulsion. Many artists have painted onto unprimed canvas, such as Jackson Pollock, Kenneth Noland, Francis Bacon, Helen Frankenthaler, Dan Christensen, Larry Zox, Ronnie Landfield, Color Field painters, Lyrical Abstractionists and others. Staining acrylic paint into the fabric of cotton duck canvas was more benign and less
Jackson Pollock technique of pouring and dripping paint is thought to be one of the origins of the term action painting. With this technique, Pollock was able to achieve a more immediate means of creating art, the paint now literally flowing from his chosen tool onto the canvas. By defying the convention of painting on an upright surface, he added a new dimension by being able to view and apply paint to his canvases from all directions. One definitive influence on Pollock was the work of the Ukrainian American artist Janet Sobel (1894–1968) (born Jennie Lechovsky). Peggy Guggenheim included Sobel's work in