Type metals

Japanese: 活字合金 - かつじごうきん（英語表記）type metals

Type alloys are available for typesetting and for paper-type lead plates (letterpress). In both cases, they must flow well when molten, shrink little when solidified, and be able to be cast into precise shapes. They must also have a certain degree of hardness and wear resistance. Practical types are lead alloys containing antimony (Sb) and tin (Sn). Typesetting types are generally made of a lead alloy containing 17% Sb and 8% Sn (melting point 270°C, Brinell hardness H _B 27), and when particularly hard is required, a lead alloy containing about 25% Sb, 12% Sn, and a small amount of copper (melting point about 300°C, H _B 30 or higher) is used. Type for paper-type lead plates must have a low melting point so as not to burn the paper, so a lead alloy containing 11-15% Sb and 5% Sn (melting point 240°C) is used, and if reprinting is expected, the surface is chrome plated to increase wear resistance.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

活字用の合金で，植字用と紙型鉛版 (活版) 用とがある。いずれも条件は溶融時の流れがよく，凝固収縮が少くて細かい型どおりの鋳造ができることで，ある程度の硬さと耐摩耗性も必要である。実用品はアンチモン Sb，スズ Snを加えた鉛合金。植字用活字は Sb17%，Sn8%の鉛合金 (融点 270℃，ブリネル硬さ H_B27 ) が主で，特に硬さを要する場合は Sb25%，Sn12%程度に銅少量の鉛合金 (融点約 300℃，H_B30 以上) を使う。紙型鉛版用は紙を焦がさない程度の低融点が必要で，Sb11～15%，Sn5%の鉛合金 (融点 240℃) を用い，重版が予想されるときは表面をクロムメッキして耐摩耗性を増しておく。

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