Controlling the variables on a jobsite to produce high-quality masonry can be difficult. Adding mortar color to the equation makes the mason's job a little tougher. SELECTING MATERIALS Most products used to color mortar combine red, black, and yellow iron oxides. Because they are lightfast, resist alkali and acid attack, and have high tinting or coloring power, iron oxides are well suited to the task. Mortar color can be uniform only when high-quality ingredients are used consistently. Clean sand, clean water, and high-quality cement are important. Mortar color is packaged in several ways: preweighed batch-size bags; precolored cements; large bags; and bulk shipments. MEASURING INGREDIENTS Because iron oxide pigments are strong, accurate measurement is essential for consistent mortar. Measuring color by volume with a coffee can or similar container is inaccurate due to the density differences in the iron oxide color. Accurately measuring water from batch to batch also is important. Too much water in a mix causes the color to be lighter. Sand generally is measured into the mortar mixer by the shovelful, an acceptable method of measurement under some jobsite conditions. PLACING MASONRY AND FINISHING JOINTS Good workmanship is important in any masonry job, including those with colored mortar joints. The joints should be tooled when thumbprint hard. Guard against overtooling the joints: this can darken the mortar color by drawing more of the fine pigment and cement particles to the surface. CLEANING THE WALL An excellent colored mortar job can be ruined by improper cleaning procedures. Using cleaning materials that are too strong can destroy the cement/sand/color bond.