What do printing plates actually look like?

Recently we had some A5 Print Handbook letterheads/invoice templates done with Centreprint. We asked them if we could have the printing plate too, so we could take some pictures. Here are those photos.

These machines are where the PDF I send to Centreprint gets turned into the actual printing plate. You can see a bit more inside Centreprint here.

A blue plate doesn't mean a blue job

The first thing you'll probably notice is that the image on the printing plate is blue. The job itself was not printed in blue – it was printed in red (Pantone 185 U to be exact). The blue is applied to the blank plate and has a slightly grippy texture to it. The ink is then applied to this and sticks to the blue areas. The ink is then applied onto a roller/cylinder which is then applied to the paper. To find out a little more about the litho printing process have a look here (Wikipedia).

Double sided on one side

Another thing you can see is that Centreprint only used one plate for the job even though it's double sided. What they do with this sort of job is print the whole lot on one side, flip the paper over and run it through again. It saves having to create two separate printing plates.