# Emulsion Running



## jrc537 (Aug 19, 2009)

Hello all,

I have only been screen printing for a short time. Here is my dilemma, when I wash out the image...it looks good.

But after it dries, some of the emulsion runs down and blocks out part of the image...it is so faint that you can't really see it, until you try to print.

When it runs, it isn't green any more...like clear but blocking the image none the less.

I am trying to dry the screen after washing out, laying horizontally.

John


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## pukingdeserthobo (Jun 3, 2008)

just spray a lil water and wipe off both hope that helps


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## simplywhat (Aug 19, 2009)

pukingdeserthobo said:


> just spray a lil water and wipe off both hope that helps


word.

do you wash out and then just let the screen air dry? or do you use a paper towel and dry off the image? using a paper towel to dry off the image right after you wash will help take out some of those runs.


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## 13Graphics (Jul 20, 2009)

Isn't this a sign of underexposed emulsion?


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## pukingdeserthobo (Jun 3, 2008)

13Graphics said:


> Isn't this a sign of underexposed emulsion?


yes it is i came back to say that but iguess i was to late


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## ASW21 (Aug 13, 2009)

13Graphics said:


> Isn't this a sign of underexposed emulsion?


 Yes, Agreed. Also might be that the coating is too thick. A thinner deposit of emulsion might be fully cured with the same exposing setup that is causing this problem. When you spray out the stencil you should spray the whole screen and not just the image area. There's probably loose emulsion that is breaking down and running into the image area and drying. 
btw...I've found that your own spit and a paper towel clear the blockage really well. Gross perhaps but it's a quick fix if it happens again.


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## midwaste (Apr 8, 2008)

ASW is right about the spit trick, that's what I used until I started blowing the water out of the openings with compressed air after washout. You have to wipe it with spit right after it dries, the longer it stays on there, the tougher it is to get off.

And, as said before, the root problem is underexposure.


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## LMB9888 (Sep 4, 2008)

I'd dry it horizontally with shirt side down.


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## BillyV (May 8, 2009)

Blot the screen dry with a paper towell.


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## out da box (May 1, 2007)

Expose longer.


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## INKFREAK (Jul 24, 2008)

Its called scum from underexposure,spit in the screen, the enzymes in your spit get the scum out better then plain water.If your using vellum scumming might be more of a problem. Or the summer heat could be degrading your coated screens faster then you think.Actually,theres a number of reasons.Good luck.


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## printing40years (Dec 27, 2008)

That uncolored scum is diazo if you are using a two part diazo emulison. It does come out with spit! Once it dries completely though, nothing but haze remover gets it out. It won't be there to run if you fully expose. 75% printers underexpose their screens and have this problems for various reasons. Make sure your bulb is the one recommended by the mfr. for that particular emulsion. Once you try a quality emulsion along with a quality 5k or 8k single source bulb, you will never go back. I make 50-60 screens a day. I also blow out the image before putting it in front of a fan to speed things along. Not much time for running.


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## drunkswithapress (Jan 15, 2009)

my personal experience with this in not letting the screen dry completely after coating it before burning it and washing it out, and putting the emulsion on too thick or not skimming the excess off. While i let it dry the excess emulsion would run down the screen and when it was drying would "clump" up and would wash out when i washed out the image. I try to skim off the excess and let my coated screen dry overnight before burning.


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## printing40years (Dec 27, 2008)

The scum in the image I am talking about is clear in color not colored. We have very low humidity here which is why the screens dry in an hour in front of a fan. Higher humidity areas naturally take longer to get all the water out of the emulsion for a nice strong screen. You could install a dehumidifier in a closed room for $100 to speed up the process if you wanted to. Coat the screens 2:2 with the sharp side of the coater scooping up slowly. That's all you need on the screen if you use a quality emulsion like Dirasol 916 or 914 from Sericol. 1-800-SERICOL


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## Outlaws#11 (Sep 19, 2008)

I had the same issue about a month ago, Now i have started fanning the screens after washing them out. I mean actually waving/ fanning the screen in the air up and down to remove all the excess water, then I put it directly in front of the fan, Haven't had an issue since.


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## printing40years (Dec 27, 2008)

I have always used a fan because I'm always in a hurry. Works great


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## lyricalgenius (Jan 29, 2010)

Hello I have a yudu and I cant seem to get my emulsion to come out right it always ripples or cracks and the plastic part that you take off i cant seem to get it off without pulling the emulsion off can any1 tell me what im doing wrong ? thanks


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## RichardGreaves (Nov 7, 2006)

*Tears of emulsion*



jrc537 said:


> ..... But after it dries, some of the emulsion runs down and blocks out part of the image...it is so faint that you can't really see it, until you try to print.


*
Tears of emulsion*
Dr. Elmar Messerschmidt coined the phrase "tears of emulsion" to describe the effect of unexposed emulsion remaining in the image area after washout. This thin film of emulsion will dry and block the image in the tiny tight areas where you can't see it. 

Screen makers quickly become experts at picking at these areas with a sharp pin to open them up, but the best method is not to allow them in the first place. 

Blotting the washed screen with newsprint will help but the best method is to vacuum the moisture from the screen with a *thin tipped nozzle*. The vacuum is best because it contains the moisture and emulsion rather than spraying it all over the room with an air pressure nozzle.

*Pictures from Sept. 2008 post*
http://www.t-shirtforums.com/screen-printing/t61976.html#post368426


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