Curling polymer plates?

letterpressstudio
on 29 Jul 08 (21:21)

I am finding that when I have dense image areas that my polymer plates curl slightly. If all I do is stick the plate on the base, the curl is more powerful than the adhesive and the center of the image doesn’t ink as thoroughly as the outer edges. I’m trying to work the plate in the opposite direction before I adhere it to the base but I have yet to see if it helps.

Anyone else notice this or have a suggestion for how to work around this problem?

Thanks!
Val

dicharry
on 29 Jul 08 (23:38)

I have noticed the same problem… especially with the deep relief plates. It seems that humidity (or lack thereof) is the main culprit here. Try picking up a hygrometer from your local hardware or Target. I believe you want to aim for a humidity level of about 50-60%.

Hope that helps.

winking cat press
on 30 Jul 08 (08:24)

I agree with Dicharry. I’ve had a few pp plates curl slightly when they went from my high-humidity area to a friend’s shop in Arizona. This resulted in the plates pulling off the base slightly at the edges during printing….. and the center printing slightly lighter. The double sided adhesive simply wasn’t up to the task of keeping it in place.

For us, the cure was simple: we glued the PP plates to hardwood blocks with Super-glue, pressing them in place as the glue cured. After that, they stayed nice and flat. It’s a rather “old school” solution to the problem, but it does work.

albertine
on 30 Jul 08 (08:44)

Having the same problem, I called up Boxcar. They suggested putting the plates in a ziplock bag with a damp paper towel for a little while before printing. I’ve found this to work well. Amount of time will vary depending on how large and curled your plate is.

letterpressstudio
on 30 Jul 08 (13:07)

Thanks for the responses. I’ll give the wet paper towel thing a try.

I must say I am very surprised that lack of humidity would be a problem because I find my basement very humid and I have no AC in the shop.

Thanks again!

paperedtogether
on 31 Jul 08 (08:04)

I second the wet paper towel thing, but also recommend adding LOTS of extra dead space around dense images when ordering plates. Also, rather than using double-sided adhesive, I’ve just used masking tape on the surface of the plate to tape the curled edges to the base while printing. {Watch out for cracking in dry weather, though.}