Back Exposure:
The photosensitive resin plate is laid flat in the exposure drawer with the support film facing up and the protective film facing down to receive exposure. Ultraviolet light passes through the support film to cure the photosensitive adhesive layer, establishing a stable base and controlling the washing depth, while also strengthening the adhesion between the support film and the photosensitive resin layer. The back exposure time is determined by the required base thickness.
Main Exposure:
Also known as front exposure, the photosensitive resin plate is laid flat in the exposure drawer with the support film facing down and the protective film facing up. The protective film is peeled off in one continuous motion, and then the emulsion side of the film is attached to the photosensitive resin plate. A vacuum film is then placed over the non-emulsion film and a vacuum is created, ensuring a tight bond between the film and the photosensitive resin layer. Ultraviolet light passes through the vacuum film and the light-transmitting portion of the film, causing the photosensitive portion of the plate to polymerize and cure. The main exposure time is determined by the plate type and the intensity of the light source. Too short an exposure time will result in a too-straight slope for the text and images, causing lines to curve and small characters and dots to be washed away. Conversely, too long an exposure time will cause the plate to become caked, resulting in blurry text. If there are characters of different sizes and lines of varying thickness on the same printing plate, a black film can be used to cover them and expose them separately. This will prevent small details from being lost during washing and ensure the quality of the printing plate.