Lapping and Cleaning Molds.
If a mold is warped (as referred to under directions for facing mouthpiece), the only way to fix it is to lap it down on a lapping block.
Figure 37 shows the lapping block B and mold C that is to be lapped.
A lapping block is one of the most essential tools to have in an office. If you do not have this block procure it at once from the Linotype Company, or one of the stock rooms. This block is of cast iron, corrugated on one face.
To use it, sprinkle a small quantity of emery and benzine on the corrugated face; then rub the mold back and forth, as shown in Fig. 37, until you have a perfect surface.
This block is also used to sharpen all the knives on the machine the same way.
A mold should be taken apart and cleaned and polished at frequent intervals, or the small grooves which make the ribs on the slug will fill up with dirt and cause the slugs to stick.
Fig. 37.