What happened to my screen?!

[TCT]

Anyone know what these marks in my emulsion are? Was there a worm sleeping on my screen while the emulsion dried?!
Murakami S thread, Aquasol HVP emulsion. We have not changed anything we have been doing...
Happened on like 3 screens.

[blue moon]

emulsion remover or some other chemical got on the screen after it was washed. It was either on your hands or it dripped down from the frame . . .

pierre

[Frog]

Pierre answered while I was typing, but our two answers may go together

I'd like to see it a little closer but at first look, I'd say that it looks like something that ran down while the screen was vertical.

[3Deep]

I think it's from a fresh washed screen that didn't get dried right or dried enough before emulsion was slapped on it.

Darryl

[TCT]

Here it is a bit closer....



It looks like it did drip down the screen for sure. Maybe there was some residue left on the frame after washout when it came out of the dip tank.
So you guys are thinking just triple rinse the frame during reclaim?

[Denis Kolar]

Emulsion remover residue, water streaks while drying, water from your hands after degreasing..........

[alan802]

Yep, happens here when my guys get their heads up their butts.  The first time it happened they didn't believe me when I told them what happened then I had them dry them with the long frame side on the ground to see which direction the streaks went and guess what happened?  Yep, you guessed right.

[TCT]

So extra rinsing is the solution? I have never seen this. I think our screens dry out pretty well, they usually sit overnight fairly close to the dehumidifier....

[Sbrem]

Like everyone else said, the fabric has some kind of crap, and it makes the emulsion crawl away (like oil and water doesn't mix). After degreasing, we always use a prep, when you rinse it off, the water flows downs in sheets; if there is a contaminated spot, the water will run around it...

Steve

[blue moon]

So extra rinsing is the solution? I have never seen this. I think our screens dry out pretty well, they usually sit overnight fairly close to the dehumidifier....

make sure nothing is dripping from your hands onto the mesh as you are taking the screens out of the washout booth, too.

pierre

[JBLUE]

Just a bad wash job. Happens to the best screen guy once in a while. Must have not got the frame itself cleaned and it dripped on the mesh or off a dirty hand.

[Croft]

looks like a drip of ink remover after rinse , probably from top of booth or inside corner of frame.

Another one you might see with a new screen washer are 4 finger prints at top of screen when they stretch there fingers out to carry screen to the drying area, they will have ink remover residue on finger tips.

[Doug B]

  This is why I always dry my screens horizontally after reclaim as well after coating.
It has solved a lot of problems except for the occasional fingerprint from the
reclaim person.

[IntegrityShirts]

make sure nothing is dripping from your hands onto the mesh as you are taking the screens out of the washout booth, too.

pierre

This. And make sure when removing the frame from the washout booth you grab it with two hands on both sides of the screen, not the top of the screen where contamination from your hands immediately mixes with water on the frame and dribbles down the screen.

[ABuffington]

Thanks everyone who posted here, you are making my tech support a lot easier!  Yes I too feel that the mesh has been contaminated and in this case I agree that the ribbon of thin emulsion we see is caused by a drip coming from the frame.  My advice on rinsing a screen is to use a commercial degreaser.  Avoid laundry soaps and dishwashing liquids, they often contain lanolin or fabric softeners that act as contaminants.  I agree on horizontal drying, it prevents drips like this. 

I also use just a hose with the end cut off to rinse the screen, pressure washers can bounce chemistry/contaminants back onto the screen.  Rinse the crease between the frame and mesh on all 4 sides first.  Then let the water stream down the screen from the top to avoid splashing back any chemicals or contaminants, rinse entire frame then the mesh on the inside and then the back side of the screen.  Handling from the sides is a great tip I never thought of.  The sheeting action of the water as mentioned in a post above is what you want to see when rinsing.  Sometimes a haze remover is needed to get out stubborn plastisol that has sat a long time to prevent fish eyes.   MSP-2 Degreaser or DGR-801 is what we use here in our labs.  MSP-2 degreaser is the best I have ever worked with, electronic grade chemistry, but dynamite for sim process halftone work where dot adhesion is the best.

Alan
Murakami Screen USA