From our previous blog, we learnt that printing plates are templates or master forms by which graphics designs(images and texts) are reproduced in massive quantities.
Printing plates varies depending on the technology. There are printing plates for CTF but in this article we are going to focus on the printing plates for CTP.
In this post, we are going to look at;
- The types of printing plates in CTP.
- Qualities of great printing Plates.
Types Of CTP Printing Plates.
CTP printing plates has three types, namely;
- Photopolymer plates.
- Silver Halogen plates.
- Thermal plates.
In the printing industry today the most commonly used printing plates are the photopolymer plates and the thermal plates.
The major type of photopolymer plate used right now is called “The violet Photopolymer plate”.
Silver Halogen plates are not used anymore because they are not environmental and health friendly.
Therefore we are going to focus on comparisons betweenThermal plates and the violet photopolymer plates.
Qualities of good printing plates.
Before we start it is important to know that there are qualities every printing plate should possess. How good a printing plate is depends on these qualities. They include;
- PHOTOSENSITIVITY.
Photosensitivity is the amount to which a printing plate reacts when light falls on it.
Printing plates with high photosensitivity are stored in dark rooms. This might cause additional cost for the user.
However printing plates with low Photosensitivity are difficult to print on when exposed in the CTP machine.
Printing plates should have photosensitivity between 550 nm to 1.070 nm.
- LASER ENERGY TOLERANCE.
Printing plates that require high laser energy for exposure usually consumes much electricity.
The amount of laser energy required for plate exposure should be between 100 µJ/cm2
and 200 mJ/cm2
RUN LENGHTS.
The run length of a printing plate is the number of prints a plate will be able to make before it begins to fade away.
Printing plates should have at least upto 100,000 prints.
Printing plates with high run lengths are preferred.
RESOLUTION.
Resolution refers to the sharpness and detail of printed images. Higher resolution means more.
In our next post...
We are going to compare Thermal CTP plates with Photopolymer plates.
Check out the link here.
