_16. Tinning Copper Shell._ Tin-foil is melted on the back of the copper shell. This is the solder between the copper shell and the metal back, without which the metal backing would not adhere to the shell. _17. Backing-up._ The flowing of electrotype metal on the back of the tinned copper shell for the purpose of making a foundation for printing (electrotype metal is an alloy of 94 per cent lead; 3 per cent tin for flowing and 3 per cent antimony for hardness). _18. Scrubbing the Cast._ A power operated scrubbing machine using a hydro-carbon oil as the cleansing medium to clean the printing face of the electrotypes. _19. Cast-sawing._ Sawing off the surplus metal of the cast before finishing. _20. Flattening the Casts._ Hand operation with mallet and flattening block to take the warp out of the electrotype caused by the contraction of the metal in cooling. _21. Rough-shaving._ Planing off superfluous metal from the back of the electrotype. _22. Finishing._ Putting the printing surface of the electrotype in perfect condition for press after leaving the foundry department. This is done by hand and requires a high degree of skill. _23. Smooth-shaving._ The finishing shave of metal from back of electrotype to bring it to the required thickness. _24. Routing._ Cutting out the high but non-printing surfaces of the electrotype by a routing machine. _25. Guard-line Sawing._ Cutting the guard lines or bearers off the electrotype to practically the finished size before blocking or bevelling. _26. Blocking._ Fastening the plate on wood base with brads driven through the metal. _27. Trimming._ Trimming the wood mounted electrotype to its exact finished size. _28. Type-high Machining._ Used for planing the bottom of the wood base so that the mounted electrotype is of printing press requirements, i. e., .918" high. ELECTROTYPING BY THE LEAD MOLD PROCESS Electrotypes made by the genuine Dr. Albert Lead Mold Process are always duplicates of fine-screen half-tones or mezzo-tints used for the highest class of commercial job-work, such as three and four color process or duo-tone printing on paper with a highly glazed surface. The largest press used in lead molding will give a maximum pressure of two thousand tons per square inch on a thirty inch ram hydraulically operated. The weight of this press is over thirty thousand pounds. [Illustration] In the lead mold process the plastic medium used is a soft thin sheet of what is called "impression lead," .040 inches thick, instead of wax, and the lead is placed on top of the original to be duplicated, instead of vice-versa, as in the wax-molding process. No "building-up" nor "black-leading" is necessary. In all other respects the consecutive steps towards the completion of the lead mold plate are identical to those used in the Wax Mold Process. ALUMINOTYPES