Are yams and sweet potatoes the same?
a technique used by commercial artists and illustrators to make drawings that can easily be reproduced and that closely resemble either wood engravings or woodcuts. Introduced in the 19th century, the process involves the use of a specially prepared board coated with a ground of chalk and glue or some similar absorbent substance, such as gesso. Textured boards with a prepared pattern or stippling are also available. The artist coats the board evenly with black drawing ink and works on it by scraping away with special tools, known as "scratch knives," those lines or surfaces he wants to appear white on the finished work. Corrections can easily be made by reapplying ink and then reworking the surface