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screen printing => Screen Making => Topic started by: ebscreen on March 28, 2012, 04:21:18 PM
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A game is afoot!
In the past 2 weeks we've popped probably 6-8 screens. That's about how many we'd normally
pop in a year or so. This is ridiculous.
A few have gone while cleaning (though no obvious reason, IE too much pressure, exists) but
many have gone while just sitting. Just had one go in the drying rack, post exposure, no mesh
contact with anything. Then an hour later, screen inserted on press, press guy was
across room washing hands, no ink, nothing, boom.
The only thing I can think of is that we recently replaced the dip sank solution. Can any of you smart
fellas suggest a way of determining this? I do have a microscope....
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i would guess your PH is too high..I had the same problem, you need to lower the PH of your solution.
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Slick. I have a PH meter as well. Now to find it....
Thank for the help Brad.
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Oh, and any idea what I should be at? (I'm guessing close to neutral)
And how to adjust? Vinegar? Baking soda?
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I went through this last year. We busted around 40 screens last year when the year before we busted maybe 8. I really haven't a clue as to why, some handling, some of the screens were being turned around every other day for a year straight, bad luck, everything at once, hell I don't know. It's still happening but at a lesser pace. Only 3 busted this year so far. I'm doing more newmans with roller mesh to see what happens but our smartmesh S thread screens haven't busted at a higher rate than the sefar and saati panels I got from shurloc, actually they have held up better.
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root cause review... you need to identify what is common to all screens. You have already ID'd the commonality of the dip tank that could be the chemical cause.
What about mechanical causes, example is there a tiny nick or burr on your scoop coater that may be weakening all screens?
Are they all failing with common characteristics example all popping on the right side of the screen= maehanical popping randomly top bottom right left etc probably chemical?
let us all know what you find please.
mooseman
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Oh, and any idea what I should be at? (I'm guessing close to neutral)
And how to adjust? Vinegar? Baking soda?
Baking soda is alkaline and will raise PH, acid will lower it. However be careful what you put in, some stuff can react with other stuff. What product are you using in the dip tank? Only emulsion remover (SMP powder) or something specific?
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GemZyne which is periodate in solution.
It has been really strong, which was expected when we changed out the solution.
MosseMan, exactly my thinking. Unfortunately the only commonality I'm seeing (aside
from the people handling them) is the dip tank. They're not popping in the same place, some
down the middle, some on the left. First thing I checked there.
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FWIW, I've noticed that the presence of certain staff in the shop directly correlates with popped screens. I've been without my usual shop help for the last few months and I haven't seen a single one go since then. I'm not sure exactly what people do to achieve this in a workflow where every single place a screen may dwell is mesh safe but it happens. My guess is the damage gets done in reclaim somewhere- grit or dirt in the scrubbies, handling too fast, too much psi on the pressure washer or.... chem's are over concentrated?
Maybe just water down that Gemzyne a little if you suspect it or noticed it was over-achieving a little. All the emulsion strippers and even some of the one-steps appear to be pretty much identical- sodium periodate and detergent, neither or which ought to be a major issue at middle to low concentrations unless the detergent agent is super agressive. So dilution may be the solution.
Do you happen to remember if all the popped screens are of a similar vintage? If you ran a big set at once it could be they've just reached the end of their elasticity.
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I was using imagemate 260 dehaze/degreaser and it was killing my mesh. Way too alkaline for mesh. The MSDS sheets will give you the PH most of the time. I know that 260 was over 12.
I have heard of people misting screens with vinegar(not sure the dilution) after reclaim and letting that dry. It supposedly helps with coating. Never tried it.
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Back in college I learned the vinegar thing--it's supposed to 'neutralize' the ph of the screen--perhaps ensuring the mesh isn't basic before coating--as Brad pointed out, polyester reacts far more favorably to acids than bases.
Take a screen you just put through reclaim, degrease it really well so the water sheets evenly, and look at it in the glare--are there little scratches everywhere?
Especially if you're retensioning rollers, they will eventually just go--be happy if they aren't on press at the time...
+1 Zoo--I get popped screens based on how dumb people are about handling screens. I was just restretching one yesterday that the channel edge got dinged so badly, it popped the next piece of mesh I put in--talk about mishandling.
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Oops nvm. I have nothing to add I just typed in the wrong little box and hit send on my phone before I realized I was an idiot. Now I know for sure. :-/
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What we recommend for neutralizing the alkaline content is a 50/50 mixture of White Vinegar and Water... Just spray a light mist on, and wipe down with a damp clot later. Should help with not getting the mesh eaten alive by the chemicals.
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UPDATE!
It was our scrub pads. I checked out a screen yesterday and saw a scratch in the mesh in a
circular direction. These weren't the typical ones we use, and were indeed a bit more rough.
Into the basura.
So, last I recall our favorite scrub pads were the red ones that you attach to a white handle.
Anyone knows who carries these?
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I avoid anything abrasive."Scrub" makes me think scratch.
I use a brush.
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Stiff bristle or soft? White plastisol is a bear to get miscified (I made that up).
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Stiff bristle or soft? White plastisol is a bear to get miscified (I made that up).
Medium ;D
No dip tanks here (though I wouldn't mind them)
I clean ink with press wash and paper towels, (If you soak in a tank, and/or use a water soluble ink degrader, a medium brush would be good here as well.
I then use a pretty stiff brush after I soften emulsion by spraying with remover.
I then use my medium brush for degreaser, or ReNuit de-hazer,
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Westar has red and white.
http://www.westarsolutions.com/vend/franmar/scrubpad.html (http://www.westarsolutions.com/vend/franmar/scrubpad.html)
I need to get a quote for those color coded ones from Kiwo. I really like that concept.
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Thanks for the link. Westar is good folks too.
I did have to get something like yesterday, so went to the local hardware store.
3M makes a similar item, a handle with replaceable pads. Not super soft, not
super rough. Replacement pads are $2 each.
We'll see!
Paper towels Andy? Some flatstock habits never die eh?
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Let me know, it would be convenient to get them at the store.
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Paper towels Andy? Some flatstock habits never die eh?
Some of it is just old habits, but I do a lot of cleaning on the press, then take out the screen and hold it for a few days.