[Fyahfly]

Hey guys, hope you're all well.

I'm having an issue with my coated screens...

I usually like to coat a bunch of screens with emulsion and have them sitting in my screen rack for the week ahead. I have read on here in several threads that screens coated with emulsion should still be fine to sit there for several months before exposing, as long as they are not exposed to any light.

My issue is that after a week or so, they seem to 'go bad'. Whenever I go to expose a screen that has been coated for one week or more, the stencil is always really difficult to wash out and sometimes doesn't wash out at all. If it does, it usually requires so much water pressure and to be wet for so long that the stencil blows out around the edges. Super frustrating. I've noticed as well that the colour of the emulsion in the stencil area after exposing is much darker than it is when I expose a freshly coated screen. I've also tried reducing the exposure time for screens that have been sat coated for longer than a week but that doesn't seem to make any difference at all.

Not sure what the problem could be. My dark room definitely doesn't have any light leaks. Could it be down to the room temperature or humidity? The emulsion is definitely fine - it's less than 6 months old and works like a dream if I expose it within a day or 2 of coating - the problem only occurs after the screen has been sat coated for a week or more. I use a dual cure emulsion, so it should have plenty of tolerance.

If anyone has any idea what could be causing this I would really appreciate your input. It's pretty frustrating having to reclaim freshly coated screens.

Thank you all in advance, looking forward to figuring this one out.

Cheers!

 

[kirkmansigns]

some emulsions list a very short shelf life. Bite the bullet and buy new emulsion and see if it does better after a week. I've noticed the same thing with pushing the shelf life of our Ulano emulsion.

 

[NoXid]

I've left screens coated with PHU for months. Just burned a couple last night.

In anycase, it is the photo sensitivity that dies when emulsion ages out, so it should all wash out like it was unexposed if the emulsion were bad. Sounds more like your darkroom is not quite as dark as you think. It might be working more like a VERY slow exposure unit, where a full exposure would take something like 4 months, so after a month you are seeing partial exposure, and after a couple of days no noticeable exposure.

 

[Industryps]

We used to have this same issue in our darkroom. We had rubylith covering the overhead fluorescent lights and when the light were off, there was no signs of light coming in. However, like you, a coated screen would only last a couple of days before we would experience the same issues. It came down to the warm, stale air that stayed in the darkroom. Since then we've installed it's own A/C unit, and no longer have that issue.
I would recommend finding a way to keep your darkroom area as cool as possible if you need to store screen that far in advance.