Using contrasts or opposites is an important painting tool. Pairing warm with cool colors, or hard edges with soft, or simple spaces with complex ones, adds intrigue, focus and power to the image. Since I like to use glazes and transparent layering in my work, an essential contrasting technique then, is the use of opaque painted areas. Not all colors are opaque right out of the tube. The newer colors, which often have unusual names like Phthalo or Quinacridone, are naturally transparent. The more common colors such as Yellow Ochre, Burnt Sienna and Cadmiums are naturally opaque. (More information about pigment differences is included in my new book, Acrylic Revolution.) To paint opaquely, I start my painting session by adding a large lump of acrylic Molding Paste in the middle of my palette. Pastes in general are opaque, and will whiten colors as well as thicken the textural quality. To the paste, I add about 15% retarder and some water, mixing thoroughly, and keeping the paste mixture in a close clump on the palette to keep it staying wet longer. As I paint, I make smaller mixtures on the palette using 1 part colored acrylic paint to1 part of the paste mixture. I usually apply it with a painting knife. A painting I recently finished, called Koi Pond, uses this acrylic technique, using the paste mixtures all applied with a knife. My paintings currently on exhibit in Santa Fe use a combination of the opaque pastes with transparent glazes.