A remedy for emulsion stains in image, preventing ink from flowing thru mesh???

[Mark @ Hurricane Printing]

I have a image i have burned 3 times (twice on a 110 mesh and once on a 156 mesh). The first 2 times on the 110 the emulsion stained some areas of the image after washout and it prevented the ink from flowing through the mesh in some areas and made the image blotchy..the emulsion I used that time was Kiwocol Poly Plus ER which is the kind you have to mix.......on the 156 i used the Ulano Orange which is ready mix. The 110 Kiwocol plus stained a lot more than the orange. I have never experienced this before....The Ulano Orange one I have not printed yet..I just burned it and let it dry...inspecting it this morning I can see a few spots where it looks like the emulsion has stained and Im afraid if i print with it I will have a blotchy image again where the ink wont flow thru.

First question, Is there a way to fix this before I print? Will screen opener fix it? Should I hit it with the pressure washer again? I really don't want to burn this screen for a 4th time.

Secondly, what would be the cause of this? I never went thru this before. I'm on my 3rd burn for a simple one color spot design.

(I use the MSP 3140 exposure unit Nuarc)

[GKitson]

Under exposure is almost guaranteed to be the culprit.  Does the open area mesh blockage look shiny/twinkly? I have seen a similar problem in the past where the light integrator settings were accidently changed and stubborn screen makers did not notice the exposure was much faster/shorter.

Re-shoot the 4th time with a exposure calculator and make sure you are fully exposing the emulsion. 

Kitson

[Frog]

"Scumming", and almost definitely caused by  underexposure as Greg already noted.
You should be able to clean the scum with a damp rag rubbed from both sides, but as pointed out, you need to check your exposure.

[mk162]

spit works very well for this.

you can also use a watered down degreaser, but I would go back to exposure times.

[dirkdiggler]

underexposed. guaranteed!

[alan802]

As Brad said, spit on it and rub it in and that will get rid of that scum.  Way back in the day when I first started, we would have a screen drying in front of the fan and water from above the image would drip down into the open mesh area of the design and because the screen was underexposed, the "scummy" water would block the open mesh and ink would no longer flow through that area.  Screen opener would sometimes work but water on a rag seemed to work better but believe it or not, spit worked best.  Now you just have to get your exposures right or if you can't do that right now then compressed air to the screen to speed dry it will keep any water from dripping down into the image.  That's how we used to keep it from happening before I knew what the issue really was.  You can also use newspaper or paper towels to dry the screen so that no water/scum is dripping down into the image area.  Once you get the exposures correct you don't have to worry about water dripping and you don't have to speed dry it.

[sweetts]

Agree with using newspapers to blot or vacuum them with wet dry vac. If you need to get it out you can use regular water on a rag and rubbed in the area to open it up. For sure the ultimate solution is proper exposure time. I even dabbed a little of emulsion remover on a rag and used that, it works if the area is open enough but you can wipe off detail if not careful.


RT Screen Designs
www.rtscreendesigns.com

[ScreenFoo]

I'd be really careful using stencil remover if you're not actually taking the whole stencil out. 

Another thing that will help you a bit 'saving' stencils like this is trying to do the rubbing from the shirt side, blotting from the squeegee side.  The squeegee side is way underexposed, and far less water resistant than the shirt side.

[sweetts]

Yes use caution with emulsion remover dilute it a bit


RT Screen Designs
www.rtscreendesigns.com

[Mark @ Hurricane Printing]

thanks for all the info..and I should have mentioned I do use news paper after i pressure wash, to dry it off..and I dry it in my drying cabinet, exposure side face down, heater on.

I will try all suggestions mentioned tonight when i get home from work.

[bimmridder]

Is Step Wedge Man (?) still around? He used to preach proper exposure all the time. I think he got through to a lot of people the way to do the test and the benefits.   Where for art thou?

[Parker 1]

Don't for get to check your film positives.

[Frog]

Is Step Wedge Man (?) still around? He used to preach proper exposure all the time. I think he got through to a lot of people the way to do the test and the benefits.   Where for art thou?

He did help drive the point home that it is not that tough to perform exposure tests to reduce if not eliminate exposure related problems, but there are a lot of folks groaning right now and cursing you Dave.
I bet more than one are praying that I don't bite.

[Frog]

What the hell,

this one's for you Dave 

[ScreenFoo]

How much is the T-shirt?