How is the printing plate made?
After imposition, each master paper-size graphic file is split into 4 separate files, one for each ink color: cyan, magenta, yellow, and black (CMYK). From there, each separate file is laser inscribed on its own printing plate, mounted on a printing press.
These thin metal plates are strong enough for thousands of prints, yet flexible enough to wrap around a rotating cylinder inside a printing press:
And the coating on the printing plate is blue, but this has nothing to do with the ink color on the printing plate.
In the past, many printing houses used a photographic process to make plates, but now most modern printing houses use large computer-to-plate (CTP) machines, as shown here:
First, a coated thermal plate is inserted into the CTP imagesetter (the large compartment on the right in the picture above), and the various areas of the plate are heated to varying degrees with a laser, depending on how much ink should be collected in each area, to output an image. The plate is rolled out of the laser chamber and passed through a special CTP plate cleaning fluid, which washes away the heated portion of the coating, leaving the negative of the image shifted.
Notice how your plates are developed to reveal the graphics.
Remember, you actually need 4 plates per master sheet, one for each color of ink. Below are 4 used plates, just off the press, to print a full-color master sheet. It can be tricky to see which colors of ink are due to the underlying blue plate, but from left to right you can see the yellow, magenta, cyan and black plates doing this work.
Huida Print-All Technology company is an advanced and professional manufacturer of producing printing plates, mainly selling CTP, CTCP, and PS plates as well as offering ODM/OEMs, especially for the offset. For more information, please click the official website link here: https://www.huidaoffsetplate.com/.