It happens in new construction: Block from different production runs are mixed in a wall; range brick are unevenly distributed; mortar color is inconsistent. It happens in remodeling and restoration: New brick, however carefully selected, just don't match the original material. COLORING SERVICE FOUNDED One person who spent 18 years with a Canadian manufacturer specializing in such corrective work developed and refined these color alteration materials and techniques to an unusual degree. His success in coloring masonry led him to found his own service company. Working with proprietary, water-based, multipolymer stains, the company's "masonry artists" use a variety of hand-application techniques to change the appearance of masonry in place. The pigments are absorbed into the pores of the masonry units or mortar to make a color change that lasts indefinitely but can be altered by further application of stain. POROSITY AND TEXTURE ARE IMPORTANT The process is said not to be limited by the degree of color change needed. Masonry can be stained from light to dark, dark to light, or to a different hue of the same value. Limitations do exist, however, based on the porosity and density of the masonry.