You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
stain
A stain is a discoloration that can be clearly distinguished from the surface, material, or medium it is found upon. They are caused by the chemical or physical interaction of two dissimilar materials. Accidental staining may make materials appear used, degraded or permanently unclean. Intentional staining is used in biochemical research and for artistic effect, such as wood staining, rust staining and stained glass.
Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.