The copper-plate was etched by the single solution of ferric chroride on gravurr-plate-making and the etching depth of plate was measured.
As the etching time was longer, the contrast of the image was higher. As the cnocentration of the solution was higher, the contrast was higer somewhat, but the contrast was more effected by the etching time. The contrast of the image was lowered without aggitation.
When sodium chroride or calcium chroride was added into the etching solution, pentrating time of the etching solution was slower. In the case of cupric chloride or magnecium chroride, penetrating time did not change in comparison with ferric chloride solution only. The etching solution added sodium chloride make higher contrast, but calcium, cupric or magnecium chloride did not effect for the contrast.
The etching, solution added ferric sulfate or ferric nitrate did not effect for the pentrating time and the contrast.