Duck Canvas is a very dense weave of canvas, using threads of a generally uniform, but of a slightly unequal size. The uneven thread allows the cloth the wear without going thread-bare. It is cross-woven in such a way as to keep rips from spreading. Canvas is a type of cotton, which means it is susceptible to the elements. Cotton cloths also require more maintenance because of it. Also, the unevenness of the cloth makes it ideal for abstract painting. Many acrylic and oil painters prefer this heavier type of canvas for its superior absorbtion and texture, while classical painters prefer a smoother canvas. This weave of canvas is also used by companies like Carhartt and Filson in clothing. Duck canvas also makes a very good drop cloth or tarp-like cover, although it is not waterproof.