Or it may be torn straight by laying the sandpaper on a bench, sand side down, holding the teeth of a back-saw along the line to be torn.

In this case, the smooth surface of the sandpaper would be against the saw.
[Illustration: Fig.154.Sharpening a Cabinet-Scraper: 2nd Step, Whetting.] [Illustration: Fig.155.Sharpening a Cabinet-Scraper: 3rd Step, Removing the Wire-Edge.] Sandpaper should never be used to scrape and scrub work into shape, but only to obtain an extra smoothness.

Nor ordinarily should it be used on a piece of wood until all the work with cutting tools is done, for the fine particles of sand remaining in the wood dull the edge of the tool.

Sometimes in a piece of cross-grained wood rough places will be discovered by sandpapering.

The surface should then be wiped free of sand and scraped before using a cutting tool again.