SU71365A1 - Method of making printing plates by chemical (catatipical) transfer of the photo image directly onto the metal surface of the printing plate - Google Patents

Description

The proposed method, in contrast to the well-known of this kind, has the goal of quickly obtaining a printing form of a raster halftone or stroke cliche directly from a photographic print, brought into contact with a metal plate after appropriate processing.

The method is as follows.

Photoprints are bleached in a 5% solution of RCST acidified with HC1 and neutralized with NHaOH, mixed with a 3% solution of NaCl and 7% solution of HNOs. All these solutions are mixed in the proportion of FeCls-100 ml, NaCl-100 ml and HNO; j-40 ml, then neutralized with ammonia until a precipitate of iron hydrate appears. A photographic print bleached in such a solution is washed in water and immersed for 10-15 minutes in a 10% solution of sodium chloride, acidified with NaOH or KCO3, or in a 10% solution of segnethova and salt mixed in equal amounts. The prepared solution should be kept for several days before abundant precipitation.

After this treatment, a photographic print is applied to the metal plate, after squeezing off the excess solution, without rinsing in water. The plate should be flat and polished. The imprint is rolled to the metal surface with a rubber roller and is pressed down from above with a small weight. After 20-30 minutes, remove the load and photographic print from the metal plate. A thin layer of silver firmly attached to it is deposited on the metal.

The next step is to process the metal plate with a silver image or text-solution, which makes the whitespace not perceiving greasy paint. This is achieved by treating typographical alloy and lead plates with a 3% sulfuric acid solution, then the excess solution is removed and then