Process for making bowls comprising acrylic plastics filled with alumina trihydrate

Abstract

Processes for producing durable three-dimensional bowls such as water basins comprising plastics preferably acrylics heavily filled with alumina trihydrate, some embodiments including visible particles such as those sometimes used for simulating nature stone. A preferred process for manufacturing the bowls of such material includes defining a flat rigid blank such as from a larger rectangular bulk sheet in the approximate top outline shape of bowl to be formed, e.g., the blank being oval for an oval bowl and circular for a circular bowl. The blank is provided a smooth side which will be the concave finished and exposed side in use. The blank is heated to a point of softening and of uniform temperature throughout, located within a molding die such as a matched molding die having a female cavity of the desired bowl shape, indexed to the die, but left generally unrestrained so that the heated blank and un-clamped edges thereof are allowed to draw inward to reduce tension loads during forming. Force is applied relatively slowly to the blank, such as from a male portion of the die, to compress the blank into the female cavity and desired bowl shape. The bowl is cooled somewhat, removed from the die, the top edge trimmed to suitable evenness, a drain hole with surrounding bevel is cut in the bowl, an overflow hole is cut near the top edge for bathroom sinks, and sanding and polishing is applied on the exposed side(s).