This tough material was one of the first to be utilized in home plumbing. ABS pipes are always black and softer than PVC pipes. They are mostly utilized for vent and drain lines, as well as other outside subsurface applications where freezing temperatures are prevalent. These days, they're also used for commercial building projects. ABS is a trademark of the Dow Chemical Company. This plastic is so named because it contains some percentage of polystyrene foam. When molten, this substance is white/grayish-white, but when cooled it turns black. There are two main types of ABS pipes: hot-dipped and extruded. Hot-dipped pipes are immersed in a bath of molten metal (usually zinc or aluminum) and then removed and allowed to cool in order to coat the plastic with the metal. The metal coating provides resistance to corrosion while also giving the pipe its color. Hot-dipped pipes are most commonly seen in residential construction projects. Extruded pipes are made by melting the plastic and spinning it into a hollow tube, which is then sliced into sections of various diameters for use in piping systems. The process can be repeated multiple times to produce tubes of different sizes. Extruded pipes are most commonly found in commercial buildings. Both types of ABS pipes are relatively easy to work with and generally have good chemical properties.