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Polymer plates disintigrating

Hi,

I’m having a problem with phoyopolmer plates. They disintigrate.

The first couple of times it happened I figured it was the fact id used white spirits to clean them after adjusting the roller height. I’ve decided that a good wipe with a j cloth does the trick now, meaning no nasties can get it. However, I’d luckily just finished a 2 colour print run when the plate, which hadn’t been cleaned or wiped was falling apart (the raised bits). Is this common? Is it an issue with the impression strength? Im using soft cotton card, with proper packing and getting a nice cripst light impression, but obviously don’t want this to happen again.

any suggestions?

thanks

Log in to reply   5 replies so far

Firstly are you producing your film correctly so that the emulsion side of the film comes directly in contact with the polymers surface during burn in (exposure). Over exposure will have an adverse effect on the polymers too as the longer you expose the plate the worse the “under cut ” becomes , we found it a problem when printing dotted lines on the heidelberg cylinders. Over washing the polymer can also cause under cut, or erosion for want of a better word. If you had the plate stored for a long period they can get a bit delicate too and they dont like damp at all.

  • modernman
  • on 11 Nov 11 (19:25)
  • Updated 11 Nov 11 (19:26)

Overexposure of plates will lead to creep, not undercut. Light will creep around the edges of the dots you are exposing, making them larger, not smaller.

Exposure through kreene is necessary to obtain a proper shoulder. A vacuum frame with a glass top won’t give you a crisp, shouldered exposure on fine detail.

Guys, thanks for the reply, but I have no idea, I buy the plates already done from a reputable company. I’ve asked them too, just waiting for an answer.

I stand corrected , youre right the dot will grow ,its the overwashing that weakens them .

Penguin

You haven’t mentioned what type of plate you are using. Is white spirits equal to mineral spirits or white gas?

Either way these should not destroy your plates though I would not use mineral spirits to clean a photopolymer plate as it would leave a residue.

If your plates are crapping out, yes, definitely talk to your supplier.

Gerald
http://BielerPress.blogspot.com