# Exposure problems



## Flipr (Sep 1, 2016)

Hey everybody.
I'm having a little problem with exposing my screen. I recently bought an exposure unit (8 uv bulbs at 160w) no vacuum but it has a lid I close and fasten. My problem is when I expose my screens and wash them, the emulsion seems to bubble then tear and even washes out part of my image. I've been exposing from 4-20 min with same results each time. Is it possible my emulsion has expired? Or do I need to expose for a longer time? 

Thank you


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## Flipr (Sep 1, 2016)

Thank you everyone for all the replies. You were all very helpful. I think the best "non response" was "figure it out for yourself". That actually worked and got things to work properly. Apparently the professionals couldn't figure out this problem.


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## WGiant (Oct 15, 2015)

Give it a little time, most people on here work 

I had this, it was the emulsion being layed down too thick. I now do my first coats with the scoop as normal (sharp side) and then go back over it immediately to sort of scoop off the xtra from each side. I only experienced this with photopolymer emulsion (AKA Hybrid) on <110 Mesh. Was really bad on 88s.

If this doesn't help then yeah, it's likely the emulsion is expired, the screen aren't drying long enough, there's too much humidity in your drying room, the screen need to be de-greased and dried thoroughly, or . . . I forget the last one.


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## Flipr (Sep 1, 2016)

Thank you for the reply. 
I don't think the emulsion is on too thick. Before I got the exposure unit I was using a 500 watt lamp and worked just fine. I had printed 60 shirts. So I decided to upgrade to a unit.
After a couple of attempts I let the screens dry for 3 hours with a fan with the same results.
Lately I'm finding that some of the emulsion is "tearing" from some parts and not washing out in others. 
No big deal. I'm sure I'll figure it out eventually.


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## WGiant (Oct 15, 2015)

Flipr said:


> Thank you for the reply.
> I don't think the emulsion is on too thick. Before I got the exposure unit I was using a 500 watt lamp and worked just fine. I had printed 60 shirts. So I decided to upgrade to a unit.
> After a couple of attempts I let the screens dry for 3 hours with a fan with the same results.
> Lately I'm finding that some of the emulsion is "tearing" from some parts and not washing out in others.
> No big deal. I'm sure I'll figure it out eventually.


I'd still give it one try with the thinner emulsion layer.

Just remembered the last problem area: Bad Bulbs. Bulbs don't just burn out, they can lose their oomph over time. It's usually an old bulb problem easily solved with longer exposures though.

I'd try thinner emulsion.


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## Flipr (Sep 1, 2016)

I'll give the thinner emulsion a try. The unit is 2 days old so it shouldn't be the bulbs.


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## djque (Feb 5, 2013)

When you post and want answer you need to also include what kind of exposure unit u you have and what brand of emulsion your using. We can guess all we want but won't get it right. I try to tell people to get a unit that people have so it will be easier to help. Like
Brown
NuArc
Ranar
Etc
I could tell you i expose my screens in 45 second and thats a wide varity of photo polymer emulsions. But I'm also using a 1k metal halide lamp. 
I had a ASC 360 unit that was a piece of **** could never get the times and the company didn't even know the times. I took it back and got my money back.


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## Flipr (Sep 1, 2016)

Thanks permalink. I'm using the ASC 360 unit. I figured it all out. I downloaded the "free exposure calculator" (no one in Toronto sells the ones I keep seeing online) found a good exposure time, but it turns out that I had some dry flakes in my emulsion bucket. I bought a new gallon and everything works great.


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## djque (Feb 5, 2013)

Flipr said:


> Thanks permalink. I'm using the ASC 360 unit. I figured it all out. I downloaded the "free exposure calculator" (no one in Toronto sells the ones I keep seeing online) found a good exposure time, but it turns out that I had some dry flakes in my emulsion bucket. I bought a new gallon and everything works great.


 i made a post asc 360 exposure unit. I did a post on how bad it was. I figured it was a asc360 u had..i hated the timer as it counted from 100m. Good luck with it. What times did u get and what screen mesh are you using.


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## Flipr (Sep 1, 2016)

Using 120 mesh at 331 sec. Single coat each sude of dual cure. Going to try a new exposure calculation on a double coat.


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## Scott Printing (Jul 1, 2016)

Hey,
Im sure by now you have resolved the problem. but if not I can give a few tips. I use satti HU42 with great results, huge exposure window. I also use standard unfiltered black light bulbs. 1st make sure your film and screen have good contact. I use a 4 inch thick piece of foam and when I close the lid my film and screen have 100% contact. With a pressure washer, decent pressure and about 2 feet distance your image should rinse out in a minute or so. With 110 mesh I get it wet and let it sit for a few minutes flip back and forth until the image rinses out. 

Also, I use the dull side of the scoop when I coat. I coat with pretty decent pressure. You dont need to lay emulsion down really thick. 

With the HU42 I basically go 
4.5 mins on 156 mesh (single coated)
8 mins on 110 mesh (double coated)
1.5 mins on 280 mesh. (single coated)

I rarely have any rinsing issues. Always be sure your emulsion is 100% exposed because if not you can have an issue with cross linking your mesh(they can be reclaimed but very very difficult.)

The HU42 does have a shelf life once mixed but I have never had a gallon last long enough to get to that point. Also, humidity can be a factor but from my experience (12 years) I never worry about it. Concentrate more on very dark positives and take care of your mesh.


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## CEGraphics (Sep 15, 2016)

Flipr said:


> Thank you everyone for all the replies. You were all very helpful. I think the best "non response" was "figure it out for yourself". That actually worked and got things to work properly. Apparently the professionals couldn't figure out this problem.



Sorry to hear you're getting some awful responses! Have you tried using an exposure calculator?


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## Flipr (Sep 1, 2016)

Ya CEGraphics. This site isn't much help anymore. But yes. I was using an exposure calculator. But I have figured it all out now. Had to do some playing around to get the answer. 
I got my exposure time down to 20sec on my 305 screens and 34 sec on my 110's


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