TSB
screen printing => Screen Making => Topic started by: redwoodtees on June 22, 2016, 04:24:42 PM
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I'm struggling with air bubbles. I am using Chromaline CP Tex emusion. I don't mix before pouring into the scoop coater. I have tried waiting for the bubbles to settle after pouring into the scoop coater, but if I wait for the bubbles to dissipate, the emulsion starts to skin over in the scoop coater. I feel like the key is finding a way to transfer the emulsion from the bucket to the scoop coater without introducing bubbles is the key (thank you captain obvious). So are there any secret techniques here? If I pour slowly, I can see the emulsion folding over on itself as I pour, trapping all kinds of air. I am working on my "pour technique". But there has to be a better way. I was thinking about finding a big syringe -- suck out of the bucket and squeeze into the scoop coater. Any suggestions?
Chris
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are they actually affecting your print or screens? we get them but we have zero pinholes.
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the larger bubbles will break while coating, usually. Really small bubbles is more like foaming, and can cause a weak stencil prone to breakdown. We pour directly out of the bucket, and don't have the issue... (and we pour slowly, to reduce the chance)
Steve
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The bubbles I am getting are larger. I can see them roll up over the edge of the scoop coater and onto the screen, leaving a long streak on the screen with no emulsion or thin emulsion. So far this has not caused me any issues on press. But it drives me crazy.
Chris
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How old is emulsion?
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Do you use the round or sharp edge?
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Depends on what the issue is. If you have an uneven stencil it's not a good deal, but plenty of people get away with murder on a daily basis in that regard.
You can coat a couple times squeegee side, coat once shirt side, and then again squeegee side and it will not change the stencil very much.
I'd throw it out there that if you get a huge streak from a bubble, you may be coating too fast?
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Do you have enough emulsion in the coater? I don't let mine get half empty.
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Did you let the emulsion degas in the container, not coater?
We let it sit in the container for several hours before we pour it into the coater.
I think the following clip actually use Chromaline CP Tex.
https://www.youtube.com/watch?v=kRMIoLqMyuQ (https://www.youtube.com/watch?v=kRMIoLqMyuQ)
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Emulsion was activated in the container (a while ago.. emulsion is probably outside it's advertised working life, but it still makes good screens ). I usually start with the coater about 3/4 full. I am going to experiment with multiple coats.
On my last batch, I poured the emulsion into the coater and immediately started coating. And I had a lot fewer issues with bubbles. I think, for me, the key is refining my technique of pouring into the scoop coater.
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Do not use expired/old emulsion.
I did and I had trouble reclaiming it.
It would have been cheaper if I threw the emulsion away.