Citric-salt Acid-free Etching
无酸蚀刻：柠檬酸-盐体系
标签：柠檬酸蚀刻, 环保, 家庭工作室, 无氯
柠檬酸 + 食盐体系（150 g 柠檬酸 + 50 g NaCl / L 温水 40–50 ℃）可在 20–40 min 蚀出 0.1–0.2 mm 铜纹，腐蚀性仅为 FeCl3 的十分之一，废液加水稀释后可家庭下水处理（部分地区需中和氯离子）。气泡略多于三氯化铁，需软毛刷轻扫；铜离子饱和后（液体变蓝绿）蚀速下降，通电 2 V/5 min 电解再生可恢复 70% 能力。适合教室与家庭工作室。
Citric acid + table salt (150 g citric + 50 g NaCl per liter, 40–50 °C) etches 0.1–0.2 mm of copper in 20–40 min with one-tenth the corrosivity of FeCl3; spent bath dilutes for household disposal (neutralize chloride where required). Bubbles are more active—brush gently; when the bath turns blue-green and slows, electrolytic regeneration at 2 V for 5 min restores ~70%. Ideal for classrooms and home studios. ---