只举一例：照相到铜板上，此时铜板成了底片。再涂上化学溶液，黑的部分腐蚀重，越黑越重。洗干净，铜板成了印刷底片。

来源: 空城之主于 2025-10-19 19:39:43 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

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