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Stencil nightmare!

1463 Views 12 Replies 5 Participants Last post by  JeridHill
Hi guys,

Im still having a problem with my stencils!

The problem is that when printing images, on certain parts of the image the ink is retained/not penetrating through and as a result parts of the image are missing.

Im using a 77t mesh (however have had this problem also on 55t) with white plastisol ink.

The image is small enough for the screen, the ink is getting thru fine elsewhere, the screen is degreased before applying emulsion, screen cleaner has been used before printing and also to try and remove the 'blockage'.

There does not seem to be any obstruction preventing ink transfer, and after attempting to clean the affected areas with screen cleaner, the screen looks totally clear just like the rest of the screen. However, subsequent prints display the same problems.

Its almost as if some invisible force is holding the ink from passing through. the only way I can get any transfer thru the affected area is to use a small squegee and press very hard (this still does not do the job fully)

Any ideas???

Thanks

Dave
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Hey Dave, so the only times we have ever run into this issue, the problem was the stencil not being washed out enough on the specific area. If you do not see any obstruction or any spot where the emulsion was not sprayed off where it should be, then it could still be like a dried bubble of emulsion residue that is clear when you look at it but still solid enough not to let ink thru. Does that make sense?
Might be, I have had this problem before and attempted to wash the screen out again to no avail. I remember on the areas of screen where this was occurring i saw a 'shining' area on the screen and tried to wash the screen thru again with wayer, also tried dabbing stencil remover on it but didnt really help. tried degreaser again but this just pulls the stencil off.
Am at a bit of a loss with it really!
http://www.t-shirtforums.com/screen-printing/t44918.html

This sounds like a suitable candidate for solving the problem.

Dry my screens vertically, and the emulsion is a little slimy after washing. I dont think its under exposed though.

Will try re- doing the screens. Means reclaiming tho. Bugger!
the only times ivee ever had the problem were when my pallet wasnt clean. sometimes there was pallet adhesive mixed with shirt lint rolled up into a ball that was preventing the ink to get through, sometimes it was tape i used to align the shirts. if the screen is completely clean and open and you used screen opener ect... i would look at your pallet. if not that.. maybe.. and its a far shot.. your screen tension in that specific area.
This is caused from underexposure. When the screens are drying the emulsion is broken down in the water and goes over the washed out area and dries. To avoid this, you need to increase your exposure time. This will stop the water from containing broken down emulsion.
its definately under exposure.any trace of slime on the emulsion when water is applied is the first idication.some of this slime is running back into your image then drying clear.ifyou hold your screen up to a light source at an angle you will see a shiny trasparent area in you image.this will not allow the ink to pass through.just up your exposure time.this will solve the problem.
Still havin problems with this, tried upping the exposure time, done 15 mins instead of 12.5 on halogen lamp with same distance between the lamp and the stencil.

Problem is when i expose for too long the image under the stencil starts to cure and i lose the definition. Suppose i could double up on the transparencies?

Tried also blowing out the image with compressed air, seems to just blow the stuff all over the image

Dave
You want to dry the screens flat. To help get rid of this issue since you can't effectively increase your exposure with your current films, place a lint free paper towel over the printable area. Don't rub it, but just dab the water up first, then let it dry. This should get rid of the excess water and not allow it to build up in your screen.
I have been drying them flat but this hasnt owrked, dabbing up excess water may be an idea.

Thinking about ddoing this and buying a small compressor to blow out the image once water is dabbed off to make sure the image is clear.

Does this sound like an idea?

Also, i presume there is no way to rescue the stencils i already have without completely reclaiming.

Dave
Thinking about ddoing this and buying a small compressor to blow out the image once water is dabbed off to make sure the image is clear.

Does this sound like an idea?
Some people tilt their screens up and blow a fan on it. A compressor could be overkill.

Also, i presume there is no way to rescue the stencils i already have without completely reclaiming.
It depends on the image. If you can touch it up, you can take a fine paint brush and brush on either emulsion and then let it sit in regular light to dry and be exposed, or there is a screen filler you can also use. It air dries, so it works a little better. For sharp lines, you could put a piece of tape on the area you want to be opened and paint the blown out areas.
With regard reclaiming the screens, the problem i have is emulsion (clear) in the image area that needs to be removed, rather than areas where it has been stripped off. I suppose i could paint stencil strip on the affected areas, bu thtis will be painstaking!

dave
Sorry, I was involved with something when I typed that and forgot the original problem!

You can work with it, but it is a little tough. You have to wet it down and rub it out without breaking down the screen. Oftentimes you break through the emulsion that you don't want to. But I have used screens like this. You may also be able to put it back in the wash area and wash the build up out with your sprayer.
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