The anal sphincters, along with the pelvic muscles that surround the end of the digestive tract, ensure controlled movement of digestive tract contents. There are many possible causes of fecal incontinence; in most cases, incontinence results from some combination of these causes. Critical to normal bowel function are:
Oilcloth is a tightly woven fabric, usually cotton or linen, which is then treated on one side to give it a waterproof finish. The coating traditionally was linseed oil, but is now more commercially sold with a PVC coating.
Early canvas was made of linen, a sturdy brownish fabric of considerable strength. Linen is particularly suitable for the use of oil paint. In the early 20th century, cotton canvas, often referred to as  cotton duck , came into use. Linen is composed of higher quality material, and remains popular with many professional artists, especially those who work with oil paint.