| 摘要 |
PURPOSE:To obtain a dot etching solution not causing environmental pollution and yelow staining on the photosensitive material processed and having superior storage stability, by mixng iodie ions (or thiourea) and thiosulfate with pH specified. CONSTITUTION:A dot etching solution contains thiosulfate and iodine ions in 1.4 mol/l or more (or thioureas in 0.6mol/l) with pH adjusted at or below 6 (preferably 5.5 or less). For example, sodium thiosulfate, 50-300g; sodium hydrogen sulfite, 5-30g; ammonium iodide, 250-600g (or thiourea, 50-100g); and water are mixed, and pH is adjusted to 5-3 to make a 1 liter dot etching solution. In addition, iodine ions may be used together with thioureas, but in this case, they are mixed in a concentration where the silver potential of the dot etching solution becomes or less than -460mV. |
