Colorants are dispersed in paints and caulks to provide characteristics such as color, hiding power, bulk, durability, and corrosion resistance. They are available in many forms and colorant types. Common colors for colorants include black, blue, bronze, brown, copper, gray, green, orange, purple, red, silver, white, and yellow. Pearlescent and photoluminescent products are also available. Important specifications for colorants include pH and oil absorption, the amount of oil required to make paint with a pigment. Typically, oil absorption depends upon the size of the pigment particle, the type of binder, and the pigment’s physical and chemical properties. Smaller pigment particles require greater amounts of binder in order to cover larger surface areas and wet each of pigment particle.
Colorants are available in several forms. Examples include dry powders, granules, liquids, pastes, pellets, and chips. Dry powders and granules are traditional forms that are available in the widest variety of grades. Free-flowing pourable liquids and high-viscosity pastes are master batches or concentrated dispersions of organic or waterborne pigments that contain solvents or diluents. They may also contain resins, additives or surfactants. Pellets and chips do not contain solvents, but may contain additives or plasticizers. These solid industrial pigments are easy to handle and feature a high pigment-to-binder ratio. Depending on the pigment and resin type, pigment levels of between 50% and 75% are achievable.
There are many colorant types. Examples include barium metaborate, barium sulphate, chromium oxide, iron oxide, lead carbonate, strontium chromate, zinc oxide, zinc phosphate, and zinc sulfide. Titanium dioxide or anatase titanium is the white pigment in most white paints and the primary hiding pigment in most other paints. Carbon black, a pigment produced by the thermal decomposition of natural hydrocarbons, is available in three types: furnace, channel, and lamp black. Other colorant types include organic and inorganic compounds, fluorescent and phosphorescent materials, and the synthetic products of chemical reactions and processes. Raw sienna, burnt sienna, raw umber, and burnt umber are naturally occurring and commonly available.
Colorants are used in a variety of products and often contain application-specific features. Common applications include adhesives, art supplies, beverages, ceramics, clothing, concrete, cosmetics, fibers, food, glass, inks, paints, paper, plastics, polymers, soap and wax. Colorants are also used in medical and biomedical applications such as tissue staining. Specialized products are resistant to heat, weather conditions, and ultraviolet light (UV). Some products are water soluble or can conduct electricity. Others contain reinforcing fibers or are free from heavy metals.
