Photopolymereplates crumbles


I’ve discovered a problem with my plates,
They crumbles on several places on the plate when I rub with my fingers. not even hard.
not everywhere. see photos

My lighting time
- 3 minutes
- 5 min washing
- 5 min drying
- 3 min afterlighting.

thx for the answer.



image: IMG9775.JPG


image: IMG9777.JPG


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From my experience, the five-minute-wash is your problem. What temperature is the bath?

What is the density of your film? It may not be dense enough, so your exposure time is too short / washout too long. Do you have a Stouffer strip?

Hey Frederik,
Your polymer comes with a written instruction sheet that will tell you all the facts you need to know about the material that you are using. If you didn’t get it you should request it from your supplier or check online to find it. It will tell you the amount of light, time and temperature of washout, drying time and after exposure. Very important to have since different polymers have different specs.

As others have mentioned, you should go back to the data sheet for the particular photopolymer material to help determine your exposure and other processing details.

In my own shop, I use a post exposure which is almost double the actual exposure time. Do the fragile elements look OK after the first exposure and washout? If so, that might indicate that you should dry longer and do a longer post-exposure. If, however, you are losing these lines in the washout stage, then the first exposure needs to be longer, or the washout shorter.

John Henry
Cedar Creek Press

If these were fine hairlines, under-exposure might lead to broken relief. But what I see is the failure of the adhesive layer which holds the photopolymer to the metal backing sheet, and that happens when it is left in the bath for too long (harsh solvents can attack the adhesive layer as well). The white appearance is a clear indication that the photopolymer has lifted from the yellow backing layer.
Sometimes too cold a bath leads people to linger, or sometimes because a thin neg partially exposes the non image area and needs extra work.