Checking Plates before Mounting...

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Checking Plates before Mounting...

Postby Katherine » Mon Oct 30, 2017 1:50 pm

Good Afternoon everyone.. A quick question. What checks are usually made on the plate quality, prior to mounting.
FTA recommends measuring durometer, thickness, plate relief, halftone dot size bulb output and line width.

We have some old school printers who feel that a visual check of print elements, including text, can be verified before the plate is mounted and put on a press- which is where we generally pick up plate defects.

What are your experiences? Suggestions?
Thank you!

Katherine
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Re: Checking Plates before Mounting...

Postby richflexo » Mon Oct 30, 2017 4:05 pm

Hello,

One more to add to your list is the tackyness test. It's a simple test that takes some experience to know if the plate will transfer ink.

With your print side facing up, curl the plate (so its opposite to the cylinder curl) and touch one corner to the opposite corner. If it doesn't stick, you've over cured it and you will have ink transfer issues.

If it sticks and doesn't release or takes a long time to come off, then its under cured.

You want a gradual release of polymer. How long should it take? Thats where the experience comes in, its hard to say exactly because its not a scientific test. But one that is a way to tell if you're over or under curing your plates.

Defects are generally obvious like scars in the plate from bad cover sheets or cuts from a lazy box cutter. Visual inspections on a light table with separations and a colour proof are sometimes sufficient before going to press if its a re run. But all of the above that you mentioned are good to do before mounting.
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