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
Color Field Helen Frankenthaler, Morris Louis, Paul Jenkins and dozens of other painters found that pouring and staining opened the door to innovations and revolutionary methods of drawing and expressing meaning in new ways. The number of artists who stained in the 1960s greatly increased with the availability of acrylic paint. Staining acrylic paint into the fabric of cotton duck canvas was more benign and less damaging to the fabric of the canvas than the use of oil paint. In 1970 artist Helen Frankenthaler commented about her use of staining: "When I first started doing the stain paintings, I left large areas