Pocono Mt. Screen Supply, Inc.

Problems Associated With Insufficient Tension

Question

We are having trouble getting enough ink laydown. We have even gone down as far as a 61 mesh for our white ink, and are still not getting good enough coverage. We coat our screens once on the print side, and twice on the squeegee side, but think there might not be enough solids content in the emulsion. Do you think a higher solids emulsion would help with our problem?

Solution

In a word...no. The impact of using a thicker stencil (whether you make it by switching to a higher solids content emulsion or simply applying more coats of the brand you are currently using) will only be felt on the ink deposit of small detail, and around the perimeter of the larger detail in your design.

Once you move a certain distance away from the edge of the stencil, it can no longer exert any influence on the amount of ink that is deposited. The responsibility for that job falls to the mesh itself, with the important factors being mesh thickness, and probably more importantly its percentage of open area.

The 61 mesh that you used to print your white with poor results normally lays down a very thick ink deposit, actually way too thick for most people! Look at your printed samples, you will see that you do not have a problem laying down enough ink. You do, however, have a problem with poor coverage.

It looks like the underlying cause of your poor coverage problems is due to insufficient mesh tension in your screens during printing. Instead of laying the ink on top of the shirt by a smooth, continuous film, you are forcing most of it into and through the shirt. The result being that you have both poor coverage, and a very heavy hand caused by the thick ink film on the garment.

In these days of rigid metal frames used with off-contact pneumatic clamps, and self-tensioning frames, there is no good argument for going to press with less than 20 newtons of tension in your screens. By printing with a tighter screen, you will then need to reduce both the off-contact distance and the squeegee pressure. By reducing the squeegee pressure, you will then allow the ink to lay on top of the shirt, instead of being driven deep into the fabric. Screen tension is perhaps the single most critical element that determines just how much control you have over the printing process, and how successful it will be.

Indeed, there are now many people who take the view that 20N is insufficient tension for their needs. That's because even higher tension levels result in better registration, and faster printing speeds with less smearing and ink build-up when printing wet on wet. Along with numerous other benefits that are outside the scope of your current problem. However, don't try to run too fast before you can walk! Invest in some decent frames and/or a new stretching system, and tension your screens so they go to press with a minimum of 20N. With the right print set-up, you should then get good coverage with your white ink through an 86 or 110 mesh, or maybe even a finer mesh count, depending on the surface of the garment.

Don't be put off by the cost of some new frames. Your rewards will be a better looking and feeling shirt. Remember that a gallon of ink will go much further, and think of all the money you will save.