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Discussion Starter · #1 ·
Alright so I'm rather baffled by my current situation. I've been using the same exposure unit and emulsion since October of 2010 and just started having issues about three weeks ago.

I have this generic 20x24 aluminum exposure unit: Aluminum UV Screen Exposure Unit 20"x24"

I use SAATI - Grafic HU42 Dual Cure.

When washing the image out, right when the emulsion is able to spray out, all the "cured" emulsion around the image starts to come off too. Also there was a time when I was new and would use things like q tips or paper towels to help get the image to come thru while washing it out, but now if I even slightly touch the screen with my finger, all the emulsion will instantly become gooey and come off.

I've been reading online it could be under exposing. So I've tried a few things.

I normally would burn screens for 6-7 minutes. Yesterday I tried 7, 8, 9, 10, 12, 16, and 20 minute exposure times. I also put brand new bulbs in and tried exposure times of 6, 10, and 20 minutes. I know the times are alittle off the wall, but I was hoping I could have atleast over exposed and still got my image to burn but that wasn't the case.

Also I just replaced my stock light bulbs with these ones: Lighting fixtures, gu10 halogen, light bulb, lamp, fluorescent, incandescent, metal halide from Light Bulb Depot.

They seem to be identical in every way to my old ones but I'd like to double check.

Any help or tips would be appreciated as I'm now at a halt and got quite a few jobs lined up. Thank you.
 

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If you live in an area with high humidity, the problem might be that your emulsion wasn't dry enough to expose. It might have been dry on the surface but not dry all the way through. When rinsing out your screens try gently wetting both sides and let the screen sit for a minute then re-wet and let it sit for another minute. Then blast it out from the shirt side only and see if that helps.
 

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Discussion Starter · #3 ·
I live in Florida so we definitely have high humidity issues. Screens have been sitting, dried, since last Wednesday though lol.

Going to try that right now. Should I keep my exposure time around normal?
 

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Discussion Starter · #6 ·
thutch15 emulsion is about 2 weeks old.

When I coat my screens, here's my process. Don't laugh lol.

I close my garage and let a hair dryer run for about an hour, getting it nice and toasty. I then coat the screens and let them sit in there for about three hours (dryer is still running along with a fan too). At this point they are dried. I've actually used them immediately following this. But if I don't need to, I remove them and place them in my office closet where they sit till needed.
 

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That's got to be one heck of a hair dryer! Sound to me like your biggest issue is humidity. I let my screens dry with a fan blowing on them in nonhumid conditions overnight just to make sure the emulsion is good and dry.
 

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Discussion Starter · #9 ·
Yeah, but not as bad. I noticed about a month ago, while washing out that it was putting random pin holes every where on the screen. I would tape or block it off and work past it. Thought it was due to my hose attachment. Replaced the attachment and then it proceeded to get worst lol.
 

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Discussion Starter · #10 ·
That's got to be one heck of a hair dryer! Sound to me like your biggest issue is humidity. I let my screens dry with a fan blowing on them in nonhumid conditions overnight just to make sure the emulsion is good and dry.
It's ridiculously strong. I stole it from my lady friend and she claimed it was her favorite haha. Humidity is definitely seeming like an issue, but for some reason I don't think it's the sole problem. Just based on the screens I'm trying to burn now, have been dried for almost a week now.

Will definitely be purchasing a dehumidifier today though.
 

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You're not letting the emulsion dry thoroughly enough. As soon as the temp and humidity go up you need to change things to keep them in an area that isn't humid. The hair dryer might make it warm but it won't dry the air. Do you have a room inside somewhere that can be dehumidified for screen drying and storing? Your closet would work with a small dehumidifier.
 

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Dry on the surface doesn't necessarily mean dry on the inside. They need to be dry all the way through and from what you've said so far it does appear that you haven't been letting them dry enough. Even sitting won't dry them if they're sitting in humid conditions.
 

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Discussion Starter · #13 ·
Gotcha. I mean I have plenty of room inside my office closet. Now that I think back, before I would try to quicken the drying rate by putting them in the garage, when I was only using the closet, I didn't have issues. But it would take 8-10 hours to dry as I keep my house at 73 degrees lol.
 

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ding ding... this is correct..

it doesnt matter if they sit for three months, if it's humid, they aren't dry.

drying, is the act of pulling all the moisture out of the emulsion.

i dont know the specifics of your particular emulsion but it's probably in the area of 10-20% solids. which means it's 80-90% water.

that water must be pulled out and into the air. if the air is humid (wet) its going nowhere.

as mentioned above, dry on the surface does not mean its dried on the inside. and the problem you are describing is wet emulsion washing out.

that hair drier is doing nothing for you but making noise.


best case scenario... coat your screens, and dry, flat, shirt side down, in a dehumidified cabinet. you can get a small dehumidifier for about 75 bucks, and build a cabinet for about 20 bucks to hold 10 screens or so.

next best, is to build a cabinet, and use a small space heater WITHOUT a fan on it. they have some 1500 watt heaters right now at walmart for 28 bucks with no fan.

a fan will blow dust onto your screen. the dust will wash out, and create pinholes.

90% of pinholes are created by improper drying and getting dust on the emulsion. or dust on the mesh before applying the emulsion.
 

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Gotcha. I mean I have plenty of room inside my office closet. Now that I think back, before I would try to quicken the drying rate by putting them in the garage, when I was only using the closet, I didn't have issues. But it would take 8-10 hours to dry as I keep my house at 73 degrees lol.
put them in the closet. put a space heater in there if you cant afford a dehumidifier.
 

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Discussion Starter · #16 ·
ding ding... this is correct..

it doesnt matter if they sit for three months, if it's humid, they aren't dry.

drying, is the act of pulling all the moisture out of the emulsion.

i dont know the specifics of your particular emulsion but it's probably in the area of 10-20% solids. which means it's 80-90% water.

that water must be pulled out and into the air. if the air is humid (wet) its going nowhere.

as mentioned above, dry on the surface does not mean its dried on the inside. and the problem you are describing is wet emulsion washing out.

that hair drier is doing nothing for you but making noise.


best case scenario... coat your screens, and dry, flat, shirt side down, in a dehumidified cabinet. you can get a small dehumidifier for about 75 bucks, and build a cabinet for about 20 bucks to hold 10 screens or so.

next best, is to build a cabinet, and use a small space heater WITHOUT a fan on it. they have some 1500 watt heaters right now at walmart for 28 bucks with no fan.

a fan will blow dust onto your screen. the dust will wash out, and create pinholes.

90% of pinholes are created by improper drying and getting dust on the emulsion. or dust on the mesh before applying the emulsion.
Thank you very much. Final question then, storing my emulsion in the garage, sealed, might lead to issues too I'd imagine?
 

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Thank you very much. Final question then, storing my emulsion in the garage, sealed, might lead to issues too I'd imagine?
store it in the fridge.

i use two containers. a gallon that is stored in the fridge. and a small pint, that i keep out. the pint is enough for several screens (over 15)

you want to use emulsion at room temperature.

so, about an hour before you coat, pour from the gallon to the pint. let it sit for an hour.

or.. i actually keep my pint filled and sitting on the shelf, because i coat daily. every time i finish coating, i refill the pint.

but the gallon... stays in the fridge.
 

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Discussion Starter · #18 ·
store it in the fridge.

i use two containers. a gallon that is stored in the fridge. and a small pint, that i keep out. the pint is enough for several screens (over 15)

you want to use emulsion at room temperature.

so, about an hour before you coat, pour from the gallon to the pint. let it sit for an hour.

or.. i actually keep my pint filled and sitting on the shelf, because i coat daily. every time i finish coating, i refill the pint.

but the gallon... stays in the fridge.
Ahhhh will do! Thank you thank you.

Thanks everyone who's gave me some input.
 

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I do all my screen printing in the basement, so it's cool and dry down there. Yes your emulsion needs to be kept dark and cold. Putting it in a garage in Florida.. you might as well store it in the oven. Way too hot. That might be part of why you've been having so many issues with pinholes too (aside from dust). Good luck. I hope everything works out now.
 

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Discussion Starter · #20 ·
I do all my screen printing in the basement, so it's cool and dry down there. Yes your emulsion needs to be kept dark and cold. Putting it in a garage in Florida.. you might as well store it in the oven. Way too hot. That might be part of why you've been having so many issues with pinholes too (aside from dust). Good luck. I hope everything works out now.
A basement is overly perfect.

Well sadly nothing has changed. I resorted back to the closet and used every tip given. Would it be the emulsion itself too? I brought it inside 6 hours before using, so it wouldn't have been hot. But can it mixed inconsistently but look consistent?
 
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