# the devil is in my screens



## denneyjr (Apr 6, 2013)

I keep having that issue that drives you through the wall.

I wash and degrease my screens before letting them dry, then applying emulsion (2 coats in the inside, 1 on the outside), letting that dry, then burn and rinse the screen. I've been doing this for a few years and haven't changed anything about my technique because it's always worked.

Now, this issue comes up in probably 1 out of 5 screens. The screen will look entirely fine, crisp images, no blockages. Holding the screen up to a light, I can tell that the image is great, no pinholes for the most part, definitely no visual blockages.

Then, for no reason, a portion of the screen won't allow ink to pass through (plastisol). After trying an initial few passes, you can immediately after a pass that most the ink has gone through as planned, but there's randomly a blockage. Once this happens, no light passes through, it's fully blocked in whatever area is affected. I can't figure it out. What causes a great burned screen to all of a sudden block ink from passing through? I can go at with the edge of a squeegee forever and sometimes, it partially comes out. Most of the time I just deal with it and after about 20-30 prints, it'll actually start transferring ink better. What is the deal?

I'm sure you guys have seen this or know which items the screen printing god accepts as a bargaining for good screens. Any help would be wonderful.


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## ShirlandDesign (Nov 29, 2009)

If your exposure units getting a little weaker there might be some emulsion scum left in the open mesh. Do you blow out your stencil with compressed air after washing it out?


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## denneyjr (Apr 6, 2013)

I don't blow it out, but I can see the benefit in that.

So there could somehow be enough remaining emulsion residue from the previous use that it could block the screen, even if I can't see it? I've also had the same exposure unit for a little over 2 years so that may be an issue.


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## Fresh Prints (Apr 13, 2011)

denneyjr said:


> I don't blow it out, but I can see the benefit in that.
> 
> So there could somehow be enough remaining emulsion residue from the previous use that it could block the screen, even if I can't see it? I've also had the same exposure unit for a little over 2 years so that may be an issue.


Scum Not from previous use, but from underexposed emulsion. It can run down the screen after washout and clog it. Try a little longer exposure. also gently pat it dry with newspaper after washing out the image. Good luck.


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## bertiewooster (Jul 7, 2007)

It's just a bit of scum that's liable to run down in to the open areas, especially if you dry your screen vertically.
As is said below padding the shirt with newspaper (or newsprint to some) is the best option, then drying it straight away. I have an old hair dryer at work it's perfect for drying the screen quickly.
Old emulsion and under exposure tends to escalate this problem!


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## TYGERON (Apr 26, 2009)

What type of exposure source are you using?

And if about 1 in 5 screens are having this issue,

is it the first one's of the day or after the exposure unit

has sat for a while?

Had an issue with first screen underexposing and 

emulsion washing out, then subsequent screens coming

out fine. I use HO UV tubes. Sean @sben763 suggested

output is significantly weaker when first used turned on

cold after sitting. I now turn them on to warm, no issue

since.


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## debbbbsy (Jan 11, 2011)

> Now, this issue comes up in probably 1 out of 5 screens. The screen will look entirely fine, crisp images, no blockages. Holding the screen up to a light, I can tell that the image is great, no pinholes for the most part, definitely no visual blockages.


Hi 

There is no problem with the screen, the emulsion or your exposure.

You are experiencing water blockage in the stencil. After you have dried the screen hold it up towards a light, and tilt slightly, water blockage will appear in the stencil as a shiny/varnish type spots.

It happens mainly in courser meshes. To prevent it, simply lay your screen flat after washing out the stencil, exposed side up, using a quality absorbant paper towel, rub across the stencil, you can actually see the water being removed from the stencil.Than dry as normal.

The only way to remove water blockage once you have set up, is with a damp/wet rag and rub gently. 

Debs xx


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## denneyjr (Apr 6, 2013)

Normally if this happens, it happens in the first couple prints. The first print is always slightly irregular for me since no ink has passed through the screen yet. It's on the second or third pass that I realized the blockage is there, and also that my sanity is about to go out the window.

I just did another 4 screens, and they all worked flawlessly. I did change some of my technique though. I normally burn the screen for 6 minutes at a distance of 15 inches. This time, I kept it on for 7.5 minutes. Immediately after rinsing out the screen, I dried it with a basic, fairly smooth rag. I added a second step where I take a fairly rough rag and used it only on the actual image to make sure there wasn't a drop of water left in the mesh. Then, I allowed them the finish drying entirely in the horizontal position, whereas normally I dry them horizontally. There were no visible blocks, and print after print, I realized either today was just a great day or the new rinse/dry method did the trick.

So, I'll keep up with the new stuff. If I have trouble again, I'll throw my troubles your way. I do appreciate the precise advice from everyone, it made all the difference.


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## 3inkpro (Nov 26, 2014)

I make one last pass to get any emulation off the inside of the screen to try and prevent that form happening in the past we would let the screens dry flat in a rack also


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