TSB
screen printing => General Screen Printing => Topic started by: CSPGarrett on January 07, 2015, 08:22:40 PM
-
Thought I would ask to see what people thought before we keep making the same mistake too many times. On our new Anatol the prints are coming out great, but many times especially on larger runs we are getting squeegee "marks" the length of the stroke (usually to one side more than the other if not both). So when we break the screen down they are still there even when using 701 or IR18 which are both good ink degraders and stain removers.
Should we be taking the squeegee side of the screens? Many times the ink is getting pushed through the emulsion right on the edge, but our exposure times are on since we have step tested our 2/2 coat a lot and know our burn times.
I should have taken a photo today of my purple screen since it was easy to see, also our pressure isn't drastic. Just enough pressure that when the print stroke finishes you can barely tell the blade was bending if at all, basically kissing. Our edges are clipped off by Anatol when we got the squeegees.
Thoughts?
-
need more info. . . where are the marks, on the shirts? is it ink or pressure marks? is the emulsion breaking or is it something else?
pierre
-
It sounds like your trying to say the edge of the squeegee is digging into the emultion. At least that is what I think it sounds like. If this is happening its the emulsion breaking down. A good emultion that has been burned correctly will last thousands of prints with even a hard sharp point on the end of the squeegee digging into the screen.
Expose longer. If your ink is penetrating the emulsion the emulsion is breaking down. This could be caused by the screen holding too much water or the emulsion is thicker then the one you step tested. Each screen will expose a little different. Exposing longer will fix almost all break down problems.
-
Are the edges rounded. Use double bevels. :)
-
I have attached a photo of one of the worse ones I had, the squeegee marks are mainly on the outside edge of the squeegee stroke (it has been recoated).
We are using Textile PV with a 2/2 coat. Exposing on a Workhorse Point 1000 with an average time of 7 Minutes. This happened on a 285 piece run (we thought this emulsion would last for long runs). I will expand our burn times another 30 seconds to a minute. Also we keep screens stored in our dark room at an average of 95 degrees and 11% humidity (I have a gauge in the office that I know what it is 24 hours a day). When loading wet screens in we get humidity up to about 28-30% but don't touch them for 4-6 hours and until it hits 10-11% consistent.
I do have sample quart of Ulano QLT to sample soon (just have to go through my 4 gallons of PV).
On press, yes the ink does push through the mesh, on the outer edges when done if you went under the press you can see a thin ink line going down the screen, usually heavier to one side.
(https://www.dropbox.com/s/m9fu9rhoe66lnwb/2015-01-08%2009.17.01.jpg?dl=0)
-
His Dropbox link doesn't seem to work but here's his pic downloaded and attached
-
What Jon said.
-
Thanks guys, about to burn a 5 color and will extend times. I always thought PV was a good emulsion so expected it to be the operator not the product.
-
Thanks guys, about to burn a 5 color and will extend times. I always thought PV was a good emulsion so expected it to be the operator not the product.
Underexposure is probably the most common problem (or root of other problems) in the biz!
-
I've got this problem too, but I've only printed 3 (three) jobs...actual FOR SALE jobs... on this new-to-me Gauntlet.
I just figured the squeegee pressure was too high, or I needed to go to higher EOM. I am currently using CCI WR-25 on everything, plastisol or not...and 2 over 2 with the sharp edge. I have a micron guage, but its got dust on it. I get consistency and I figure that--at least--is a good thing for my stage of development.
So maybe I'm a little underexposed too. But I'm afraid I can't hold all the dots if I go up very much.
How about post exposure for a harder stencil? Does that even really work for THIS particular problem?