In traditional offset printing plates, most of the text is discharged by the computer. After correct proofreading, the copy paper is used to copy the film, and the text is manually imposed according to the layout and the text is added to the designated position.
The bright-room machine was exposed with ultraviolet light and could not penetrate the pattern, so the bright-room machine could not copy the pattern. In the past, we copied the paper and most of them were copied using a darkroom copying machine. In the darkroom, it was both error-prone and inconvenient. We have found in practice that UV light can penetrate through sulfate paper. According to this phenomenon, we summed up the method of copying paper samples using the bright room copying machine for reference by peers. Methods as below:
First, use cotton wool with a little ethanol to wipe it onto the paper. The amount of rubbing should be based on the wet paper pattern. Then take the sample of the alcohol directly to the copy machine on the bright room for copying. It should be noted that the exposure time should be adjusted from 5 to 7 pulses in the past to 25 to 30 pulses in order to copy the film. And easy to operate.