platemeaking problem

I had my film professionally made and tried using DIY exposure setup as described by Maggie Bergman. My problem is, polymer under the film doesn’t seem to get exposed, everything washes out even with exposure of 16 min. The uncovered polymer did harden at 5 min though. Looks like the film, even the clear film stops all UV from hitting polymer. What gives?

Am using 15W UVc bulb.

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I’m no expert, but it sounds like you need to try and isolate what’s messing up your exposure. It could be a few things.

I’m assuming you’ve tested with a grayscale step test? That’s going to come first in getting your time dialed in.

Some materials do hinder UV transmission, such as tempered glass, but if they are clear they simply require a longer exposure in most cases.

Let us know if you have any luck!

James Beard
Vrooooom Press

Hipost, are you using a single 15w UVc bulb?

Silly question. Did you remove the protective acetate sheet before exposing the photopolymer plate? Only reason I ask is that if you did not, it will result in the plate washing out even.



A careful reading of you first post gave me a clue to your problem. The bulb type you are using is not in the proper wavelength range to properly activate the crosslinking of the photopolymer. If you change to a UV-B bulb, you should have better results.

The bulbs used in the commercial photopolymer plate processors are UV-B (white tubes), not the “black-light” tubes used in flourescing displays.

The UV-C tubes are used for germicidal use in water systems and some medical applications. As I understand it, UV-C bulbs are also used in de-takifying photopolymer flexo plates after development, but are not used in relief-plate processors.

You should use a tube similar to Ushio 3000319 G15T8E (a 15 watt bulb) Which will give you relatively short exposiure times. Ask local suppliers or search online for 15 watt UV-B flourescent bulbs.