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
Shaped canvas and Norman Carlberg. The Filipino artist Pacita Abad (1946–2004) stuffed and stitched her painted canvases for a three-dimensional effect, combining this technique (which she called "trapunto", after a kind of quilting technique) with free-wheeling mixed media effects, riotous color, and abstract patterning suggestive of festive homemade textiles, or of party trappings such as streamers, balloons, or confetti. The total effect is joyously extrovert and warm – quite opposed to both the minimalist and pop art versions of "cool". In reference to the shaped paintings of Jack Reilly (born 1950), Robin Landa emphasizes the power of the shaped canvas to create