Screen Clogging when exposed to direct sunlight

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dead.cities
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Screen Clogging when exposed to direct sunlight

Post by dead.cities »

I've been having a problem lately. With most of my screens, especially my 305's, 230's, and 195's, the small halftones are clogging. I have a clothing line, so we have the same design burned in the screen for at least 6 months and we use that screen several times during the 6 months. For example, I just printed a high detail print with a 195 mesh screen in white plastisol ink and it came out perfect, then I used vw ink wash(same thing i've used for years) to clean the ink out. I then printed a white shirt in black ink, and all the small half tones are clogged. Here are a few things that might be the culprit. Keep in mind that this is the first summer we've been in a location with no A/C and there was a hail storm recently so the land lord replaced the skylight, but with a completely clear skylight. We had a coated one before, blocking out most of the harsh sunlight. 1. There's no A/C and it's over 100 degrees outside 2. The skylight above the press is completely clear, so the sunlight is beaming down on the screens 3. I'm using 3 or 4 fans. All of them pretty small, like what you would use in your house. 4. The holes seem to clog while I clean the screen, not during production.

My best guess is that the mix of ink wash and plastisol ink is bonding together and clogging the screen because of being in direct sunlight. If you have any advice or tips let me know. (I'm having my skylight coated today just fyi)
Attachments
this is the one that was clogged
this is the one that was clogged
IMG_0442.jpg (85.85 KiB) Viewed 6365 times
this is the one that came out perfect
this is the one that came out perfect
IMG_0441.jpg (76.64 KiB) Viewed 6365 times
whimsywhit
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Re: Screen Clogging when exposed to direct sunlight

Post by whimsywhit »

It's up to a 100 degrees every day for six months out of the year, and we've never had an issue with clogged screens, unless all the ink wasn't washed out when the screen was taken off the machine. I've had quite a time with 230's that were saved and reused. Are you washing them yourself, or do you have a helper who does all that for you? If you have a helper, have they slacked, LOL? I have had ink dry in the screen when too close to flash unit, so it COULD be possible that this was happening to you. We have a LOT of humidity here, so that may be why ours don't dry up and clog as bad. Are you taking them down immediately and washing them and putting them right back on the machine? Sometimes if I don't get all the cleaner out it makes the screen clog even worse, and takes ten or fifteen test prints to get it going again.
dead.cities
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Re: Screen Clogging when exposed to direct sunlight

Post by dead.cities »

When you say "unless all the ink wasn't washed out," how much do you mean? I usually cover the front and back with screen wash and wipe each side off 2x each, so when i wipe it off the second time, there's still some of the ink color on the shop towel, but the screen appears to be clear. Do I need to repeat this process until the shop towel is colorless? I wash them myself and it seems my 2x on each side method has worked out great for the 5+ years I've been doing this until recently. When I wash them between colors, I do my clean 2x(or more) on each side process while the screen is still clamped on the press, then I put the new ink on and start production right away. I'm really thinking it's the direct sunlight from the sky light that's causing the problem. That's the only thing that has majorly changed in the past year. I think a combination of the ink and screen wash used on the screen while cleaning the screen dries and clogs the screen when exposed to that sunlight. I will, however apply all of your advice to make sure I knock out everything that may be the culprit. Thanks!
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