Preparation of printing plates and cylinders with chloro-bromide resist-forming film

Claim 1

A METHOD OF PREPARING INTAGLIO TYPE PRINTING PLATES, CYLINDERS AND THE LIKE, COMPRISING EXPOSING A HIGH CONTRAST, ORTHOCHROMATIC, SILVER CHLORO-BROMIDE RESIST-FORMING EMULSION TO LIGHT RAYS FROM A PREDOMINANTLY YELLOW LIGHT SOURCE THROUGH A BLACK AND WHITE CONTINUOUS TONE TRANSPARENCY OF A SUBJECT AND A HALF-TONE SCREEN HAVING OPAQUE AND TRANSPARENT AREAS FOR A TIME SUFFICIENT TO PRODUCE A SCREENED IMAGE IN SAID EMULSION WHICH, WHEN DEVELOPED, HAS A HIGH CONTRAST, THE EXPOSURE BEING STOPPED SHORT OF THE POINT WHERE THE HALF-LIGHT OPENINGS CLOSE UP, REMOVING THE SCREEN, AGAIN EXPOSING THE EMULSION TO LIGHT RAYS FROM A WEAK PREDOMINANTLY BLUE LIGHT SOURCE THROUGH SAID TRANSPARENCY FOR A SUFFICIENT PERIOD OF TIME TO PRODUCE A CONTINUOUS TONE IMAGE IN SUCH EMULSION, WHICH WHEN DEVELOPED, HAS LOW CONTRAST AND IS IN REGISTER WITH SAID SCREENED IMAGE IN SUCH EMULSION, SAID EXPOSURE FROM SAID WEAK LIGHT SOURCE BEING VARY SHORT AS COMPARED WITH THE YELLOW LIGHT EXPOSURE SO THAT ITS ACTION IS ON THE LOW END OF THE DENSITY EXPOSURE CURVE OF THE RESIST-FORMING EMULSION, THE YELLOW LIGHT EXPOSURE WITH SAID SCREEN AND THE BLUE LIGHT EXPOSURE WITHOUT SAID SCREEN BEING IN ANY ORDER, DEVELOPING SAID EMULSION WITH A HARDENING DEVELOPER, FIXING THE EMULSION, APPLYING THE EMULSION TO AN ETACHABLE PRINTING SURFACE AND ETCHING SAID SURFACE THROUGH SAID EMULSION WITH THE HARDENED AREAS THEREOF AS A RESIST.

Claim 2

A METHOD OF PREPARING INTAGLIO TYPE PRINTING PLATES, CYLINDERS AND THE LIKE, COMPRISING EXPOSING A HIGH CONTRAST, ORTHOCHROMATIC, SILVER CHLORO-BROMIDE RESIST-FORMING EMULSION TO LIGHT RAYS FROM A PREDOMINANTLY YELLOW LIGHT SOURCE THROUGH A BLACK AND WHITE CONTINUOUS TONE TRANSPARENCY OF A SUBJECT AND A HALF-TONE SCREEN HAVING OPAQUE AND TRANSPARENT AREAS FOR A TIME SUFFICIENT TO PRODUCE A SCREENED IMAGE IN SAID EMULSION WHICH, WHEN DEVELOPED, HAS A HIGH CONTRAST, THE EXPOSURE BEING STOPPED SHORT OF THE POINT WHERE THE HALF-LIGHT OPENINGS CLOSE UP, REMOVING THE SCREEN, AGAIN EXPOSING THE EMULSION TO LIGHT RAYS FROM A WEAK PREDOMINANTLY BLUE LIGHT SOURCE THROUGH SAID TRANSPARENCY FOR A SUFFICIENT PERIOD OF TIME TO PRODUCE A CONTINUOUS TONE IMAGE IN SUCH EMULSION, WHICH WHEN DEVELOPED, HAS LOW CONTRAST AND IS IN REGISTER WITH SAID SCREENED IMAGE IN SUCH EMULSION, SAID EXPOSURE FROM SAID WEAK LIGHT SOURCE BEING VARY SHORT AS COMPARED WITH THE YELLOW LIGHT EXPOSURE SO THAT ITS ACTION IS ON THE LOW END OF THE DENSITY EXPOSURE CURVE OF THE RESIST-FORMING EMULSION, THE YELLOW LIGHT EXPOSURE WITH SAID SCREEN AND THE BLUE LIGHT EXPOSURE WITHOUT SAID SCREEN BEING IN ANY ORDER, DEVELOPING SAID EMULSION WITH A HARDENING DEVELOPER, FIXING THE EMULSION, APPLYING THE EMULSION TO AN ETACHABLE PRINTING SURFACE AND ETCHING SAID SURFACE THROUGH SAID EMULSION WITH THE HARDENED AREAS THEREOF AS A RESIST.