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Discussion Starter · #1 ·
I having some bad problems. Out of the blue, my emulsion is wanting to break free of the mesh when I go to wash out the stencil. Any ideas? I have been troubleshooting for week and just can nail down what has, all of a sudden, gone wrong. See pics.

The first two photos are of the substrate side.
The second two are of the squeegee side.
 

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Discussion Starter · #3 ·
1:1 coat. Never had trouble in the past 4 years with the 1:1.

Reclaim with dip tank and 1400 psi.
Degrease/dehase. pressure wash and flood screen. Dry frame and into the drying cabinet set to 30% RH & 80deg. Once all screens are 100% dry. Then the 1:1 and back into an identical drying cabinet.

Thanks in advance for the help!!!!!!'
 

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As ad design said many problens can cause it to happen.

Has your emulsion expired?
Is your exposure time correct?
Is the pressure you wash the stencil out with too high?
What kind of solvents are you using to clean the screen with?

I had problems with my stencils washing out and found out my emulsion was out of date because im an idiot and didn't check it lol

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This looks like a under exposure problem. It the emulsion was expired it would wash out all or none.

What exposure unit. Could need new bulbs, if florescent type black lights they can drop off very quickly. Also an be affected by temperature if the lights are dancing then let them prewarm for 5 min and retry If single point they will usually drop off at a slower rate. You can just add time to see if that can be issue. Bulbs should be changed every 1-2 years depending on their use.

Every thing else seems to be good from prep to drying to the proper humidity levels. Unless your degreasing with dish washing liquid.
 

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Photopolymer?
Are you drying them, then turning off dehumidifier and leaving time after which you then expose?
Photo will reabsorb moisture.

I say this, because we are in humidity season for many.
Agree with Sean - looks like exposure issue, but other than bulbs, this can happen if emulsion reabsorbs moisture after you have dried it.
Wet emulsion does not expose and will peel off the mesh
Diazo reabsorbs moisture much less efficiently, FYI.

Here's hoping there's no sudden hidden ads (private joke - my apologies in advance)
 

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Discussion Starter · #7 ·
I figured it out..... : /

My supplier shipped me a different emulsion..... I usually use "textile pv" but I was sent "textile phu". This explains why the sudden change.... Still doesn't explain why I can't get them to burn correctly. If Tuesday rolls around and Im still having problems I will hop back on!

Thanks to all for your help!!!
 

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Actually that explains it all. Even though they are both photopolymers the textile PV is 42% solids and the PHU is 50% solids. This simply means you are getting more EIN(emulsion over mesh). So your stencils are thicker and require more exposure time. Could be as much as 1:00.
 

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Discussion Starter · #9 ·
I was wrong... I have been using the phu all along. I thought switch may have happened. I have picked up a gallon of pc701 from imagemate. Were giving it some test runes today. The emulsion is a BIG switch. Upon initial runs we were under exposing quite a bit but we're not getting the strange puckering around the design. We also replaced the bulbs in our BL exposure unit. My supplier did admit to me that a truck had been delivered from Saati to a wrong address and it had sat outside for several days in 10deg weather.... This might explain a lot! Has anyone dealt with frozen/thawed emulsion before? I know it's a no no but I was curious what the result of frozen emulsion. I will post final conclusion once we get there.
 

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Some of the pure photopolymer emulsion are freeze stabile but Saati doesn't say either way. The wrinkling your seeing is from the emulsion not proper cross linking. This can be due to many reasons. Under exposure, emulsion absorbing humidity after dried which causes under exposure, could also be problems from the freeze.

since your using BL even 10F difference in the shop can cause a difference. I've had some emulsion get partially frozen in the fridge and work. Also when I used the BL exposure unit everything be fine then all of a sudden not work and all I had to do is let the exposure unit on for 5-10 min the expose screens. If your exposure unit has vacuum you can usually tell if its humidity issue as the emulsion seem to get tacky. This didn't happen when I used a compression top unit.
 
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