potcher

from The Century Dictionary.

• noun Same as potching-engine.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who, or that which, potches.
• noun (Paper Making) a machine in which washed rags are stirred in a bleaching solution.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A machine in which rags, after being washed, are stirred and bleached as part of a process for making paper
• noun The operator of such a machine; a potcherman