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screen printing => Screen Making => Topic started by: 3Deep on January 10, 2014, 11:51:49 AM
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Ok here is my question, I like to use at least two different emulsions a dual cure and a pure polymer, while I know the dual cure has a shelf life and the pure is pretty forgetting would it be best to get screens ready with the dual cure and just store then. I,m thinking it might be best than just let it sit in the bucket to long, since I use both at the same time. How long can a coated screen with dual cure last I guess is my real question, some months it doesn't matter as we can run thru a gal pretty quick, we don't do the 30 to 40 screens a day like other shops.
Darryl
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That's a great question. I don't have any insight to shelf life really and we've been lucky that we haven't had to test the lifespan. I know for our PP's we have had screens with really low or high mesh counts sit in the dark room for probably 6 months or so and still develop a stencil. You can tell an old screen from a new one but they still spray out just don't try to hold 4% halftones on those older screens. I know back when we used dual cures we weren't as busy and using a screen that had been coated for 4-5 months was more common and still we didn't have any total failure to expose.
I didn't give much to go off of but that's our limited experience with shelf life.
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This is the reason that has shyed us away from going dual cure recently -- the short shelf life and not wanting to break down the gallon into parts to sensitize only parts with the diazo. However, we used to use Chromaline's udc-2 many years ago, unaware of what is probably a short shelf life after being sensitized, and we probably used a gallon every 6-8 months if that. Never had issues exposing -- but now that long runs of dc printing is in play, the emulsion not operating at optimal performance is a concern/risk. But it may be worth a shot in the future, as in theory, we should be able to hold better detail than the Aquasol HV that we're using.
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I don't like keeping ready screens for too long because it hardens in the cabinet.
How fast it hardens depends on the quality of the emulsion.
I have some cheap emulsion for water-based inks that will harden after 2 days in the cabinet. Extremely difficult for fine detailed arts.
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I've had great luck with good DC's, found a screen in the corner of the screen room that had been coated for a few months, and besides a little extra time developing worked fine. Back when I was doing pints in college LX-680 would last me two semesters if I kept it in the fridge. I try not to store coated screens more than a month and rarely have halftone issues. (for whatever reason)
Rough part is, like Alan mentioned, your resolution is not going to be as good when you push the shelf life, and chances are the reason you have a DC is for the resolution, so that's kind of a catch-22.
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I'd rather store coated screen than liquid emulsion. We're at a point where gallons get used fast enough that the bottom 1/4 doesn't cottage cheese up on us, but a coated screen in a light-fast environment should last months longer than liquid/diazo'd emulsion
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This is the reason that has shyed us away from going dual cure recently -- the short shelf life and not wanting to break down the gallon into parts to sensitize only parts with the diazo.
I've been using Saati Grafic HU42 for awhile now. Lasts at least 60 days after mixing if kept in a relatively cool room. I've only used it a little with waterbased, but it's supposed to work with it. Stencils wash out quickly and completely.
Excellent reclaim, too. No snotty balls of emulsion gumming up my scrub pads.
I buy quarts so I don't have any sitting around going bad.
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Great stuff guys this is what I was looking for, but I see it's still kinda in the middle of the road on which is best. I do agree that fresh dual cure is what I like to use for halftones screens and pure polymer for everything else, sometimes I see a good price on products and overbuy, which becomes a waste of money when it goes bad before we use it...imagemate so far has the best dual cure DC-521 we've used.
Darryl
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I had some coated QTX screens I put in storage (cardboard box) for over two years. They still exposed fine for halftones.
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Polymer I'd coat and store for maybe a month max. Dual cure maybe 2 weeks.
It all depends on the heat and/or humidity in the screen room. Keep em cool and dark and they should store fairly long and still expose well.