Hammer face

Holonyms: hammerhead, head < hammer

Source: wiktionary

Tempering Steel. (Haswell. [i.e., quoted from Haswell's Engineers' and Mechanics' Pocket-book]) Steel in its hardest state being too brittle for most purposes, the requisite strength and elasticity are obtained by tempering—or letting down the temper, as it is termed—which is performed by heating the hardened steel to a certain degree and cooling it quickly. The requisite heat is usually ascertained by the color which the surface of the steel assumes from the film of oxide thus formed. The degrees of heat to which these several colors correspond are as follows: At 130, a very faint yellow … [and] At 450, a pale straw color … Suitable for hard instruments; as hammerfaces, drills, &c.

Source: wiktionary

The small end is first hardened by dipping in the water as shown at Fig. 132. As soon as this end is cooled the position of the hammer is instantly reversed and the face end hardened. While the large end is in the water the smaller end is polished and the temper color watched for. When a dark brown scale appears on the small end the hammer is again reversed bringing the large end uppermost and the pene in the water. The face end is then polished and the temper drawn. If the large end is properly hardened before the temper color appears on the small end, the hammer may be taken completely out of the water, the large end polished, and the colors watched for on both ends at once. As soon as the end shows the proper color it is promptly dipped in water, the other end following as soon as the color appears there, but under no circumstances should the eye be cooled while still red hot. For some special work hammer faces should be left harder, but for ordinary use the temper as given above, is very satisfactory.

Source: wiktionary

[…] indispensable for removing tarnished spots or stains from nickel or chromium parts such as bumpers, door handles, plated hardware or tools. The latter include dolly blocks, spoons and hammerfaces. Not only plated ware but parts like steering ball studs, drag link ball cups, carburetor parts, and others with polished surfaces can be cleaned of rust and dirt on the buffing wheels.

Source: wiktionary