How & Why Check a Screen’s Tension?
There are several types of screen frames / ways to stretch a screen with the most common being what are referred to as “stretch & glue”. Every wood and majority of 1 piece aluminum frames are stretch & glue in which the mesh is stretched and then glued around the edge of the frame. Stretching a frame is not terribly difficult, but if the mesh is not stretched at the right tension the screen will not be able to hold registration because it is baggy. Screen tension is very important for not only registration but many other problems. The second most common type of screen printing frame is called a Newman Roller Frame. Newman roller frames are made up of several pieces and allow the mesh tension to be adjusted because it does not use glue, but rather locking strips to hold the mesh in place. It is important to know that more tension is always better, but each mesh count and type of mesh have different recommended tensions for optimal printing results. Also know that a screen mesh count can come with different weaves which will affect how much tension should be used. As you can see screen stretching is a little bit of an art because of how many variables are involved.
How to Measure a Screen’s Tension
In order to measure a screen tensions a tension meter must be set on the mesh of the print side of the screen, which will measure the amount of newtons of force (tension). The tension meter should be placed in the dead center of the screen and measure both the width and length of the screen. Both the length, referred to as the “waft” should have the same tension as the width of the screen, referred to as the “weft”. A quality screen tension meter will typically cost around $500 and must be recalibrated over time to make sure it is delivering accurate readings. It is important that every new screen that is purchased has its tension measured as not every screen stretcher stretches screens at the correct/high tension that they need to be. So always double check new screens to avoid having to use a baggy screen until it is again re-stretched.
