screen printing > 4 Color and Simulated Process Printing
impact of squeegee pressure on halftone ink deposit
blue moon:
Doug,
what happens if you push harder and drive that dot in? I would imagine more dot gain, but if this i something that can be controlled, we should be able to get more ink on the garment.
When is more pressure too much pressure (on the squeegee)?
pierre
DouglasGrigar:
--- Quote from: blue moon on May 14, 2011, 12:43:53 AM ---Doug,
what happens if you push harder and drive that dot in? I would imagine more dot gain, but if this i something that can be controlled, we should be able to get more ink on the garment.
When is more pressure too much pressure (on the squeegee)?
pierre
--- End quote ---
Good question - the above was printed with about 25 -30 pounds of pressure (and for reasons I can go over later) - where do we go from here and is that too much pressure? I have thoughts and have tested for some results but of course that was not the point of the post - the point was the conversation about the issue.
How much can we flatten the garment substrate threads and weave before we have the blade bend over and have a loss of control?
This subject brings up loads of questions that need to be tested, studied, and if possible applied...
blue moon:
--- Quote ---Good question - the above was printed with about 25 -30 pounds of pressure (and for reasons I can go over later) - where do we go from here and is that too much pressure? I have thoughts and have tested for some results but of course that was not the point of the post - the point was the conversation about the issue.
--- End quote ---
well, we can fix that!
why waste a good topic? Here is a new thread . . .
soooo,where do we go from here and is that too much pressure?
jsheridan:
--- Quote from: blue moon on May 14, 2011, 12:43:53 AM ---Doug,
what happens if you push harder and drive that dot in? I would imagine more dot gain, but if this i something that can be controlled, we should be able to get more ink on the garment.
When is more pressure too much pressure (on the squeegee)?
pierre
--- End quote ---
Squeegee pressure is mute in relation to the ink volume being passed through the mesh. You can't put any more ink through a screen than the stencil thickness will allow. This is the single largest problem with screenprinters, they think they can get more ink on the substrate by adding more squeegee pressure. The only thing excessive squeegee pressure does is make things worse. It increases dot gain, drives the ink into the substrate, forces fibrillation and reduces the overall opacity.
The only way to get more ink ON the shirt is to make a thicker stencil.
blue moon:
--- Quote from: jsheridan on May 14, 2011, 10:21:49 AM ---
--- Quote from: blue moon on May 14, 2011, 12:43:53 AM ---Doug,
what happens if you push harder and drive that dot in? I would imagine more dot gain, but if this i something that can be controlled, we should be able to get more ink on the garment.
When is more pressure too much pressure (on the squeegee)?
pierre
--- End quote ---
Squeegee pressure is mute in relation to the ink volume being passed through the mesh. You can't put any more ink through a screen than the stencil thickness will allow. This is the single largest problem with screenprinters, they think they can get more ink on the substrate by adding more squeegee pressure. The only thing excessive squeegee pressure does is make things worse. It increases dot gain, drives the ink into the substrate, forces fibrillation and reduces the overall opacity.
The only way to get more ink ON the shirt is to make a thicker stencil.
--- End quote ---
well, I agree with a little caveat. . . the amount of ink deposited probably resembles a bell curve. There is a max that can be deposited with the given stencil and squeegee combination. If the settings are not in the optimal position, some changes can still be made to increase the amount of ink deposited. So yes, there is usually a way to add more ink.
What I am not sure about is the impact of the softer squeegee and the really low angles. It is pretty obvious that both of those will lay down more ink, but I am not sure why. They also negatively impact the ink deposit by increasing the dot gain. Or . . . are they just spreading the ink more and thus appear to lay down more?
The question in the end is: "Where on that curve is the right balance of ink deposit, dot gain and all the other factors?"
pierre
pierre
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