Answers to frequently-asked questions
You need to know that the instrument used to measure durometers is itself called a durometer. This device has an indenter pin, which is pushed onto the surface of the squeegee. The resistance in A Shore units is read from an analog dial.
Choosing a squeegee durometer, available from 50-95 Shore A, depends on your substrate, mesh count, and screen tension.
Very soft squeegees (for example, a 55 durometer) are soft enough to conform to varying garment thicknesses or uneven platen surfaces. However, they tend to bend under high squeegee pressure.
Harder squeegees (for example, an 80 durometer) are much less forgiving and will not print an even layer of ink on an uneven surface, such as a textured weave. However, these higher durometers are required to stand up to the high pressure needed to print at high speed or with high-opacity, high-viscosity thick plastisol inks.
Squeegee manufacturers, in pursuit of a you-can-have-it-all squeegee, have captured part of the market with alternatives to the single-durometer squeegee.
A multidurometer squeegee offers two durometers on the same blade and is available in two styles. The first is the front-back dual-durometer squeegee (for example, a 60/90 combination). One disadvantage of this style is that it offers only one printing edge and must be rested after sustained use. Pulled in only one direction, it tends to bow out. The harder back of the blade is also less permeable to solvents and tends to swell less than the lower-durometer printing layer.
The triple-durometer blade (for example, a 70/90/70 combination) was a natural step in the evolution of the squeegee. In our example, by laminating softer polyurethane on both sides of the 90-durometer material, the printer has two working edges and can avoid the bowing and warping problems of the dual-durometer squeegee.
Another answer to the must-be-stiff-to-avoid-roll-over-but-soft-to-follow-the-substrate question is to modify the blade holder. For example, the Indexable Squeegee®, from Printer's Edge, Warren, OH, has a squeegee holder that reduces the unsupported blade height, and thus maintains the rigidity of the squeegee (which can be a soft 60, or even 50, durometer). The blade is then advanced from the holder as needed, somewhat similar to the action of a mechanical pencil.
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