Not to be confused with blade profile, the squeegee’s blade edge profile refers to its sharpness. Edge profile establishes the amount of ink that will ultimately be delivered to the substrate. The sharper the edge, the less ink it will deliver. The amount
of ink going through the screen affects the resolution of the image: the less ink that is deposited, the sharper the printed image.
Mixing these three parameters in different combinations presents a wide range of possible squeegee types. For practical use, the primary combinations can be grouped to provide 12 general squeegee types.
Since a squeegee can be either sharp or dull and the profile can be basically one of three shapes, this gives rise to four possible combinations:
1. Square/rectangle profiles with sharp edge.
2. Square/rectangle profiles with round edge.
3. Beveled profiles with sharp edge.
4. Round profiles with no edge.
Each of these combinations can occur in one of three general durometers (soft, medium and hard), for a total of 12 squeegee types. Selecting the appropriate squeegee out of these 12 types depends on the nature of the product being printed and a near infinite variety of production variables. Those variables include the substrate, ink, image, equipment and operator skills. Substrates, for example, can be hard or soft, smooth or rough, even or uneven, absorbent or nonabsorbent, etc. Inks may be opaque or transparent, tacky or non-tacky and high or low viscosity, etc.
The image can comprise high or low resolution detail, or it may simply be a coating that covers the entire surface of the substrate. The printing equipment you use may be new or old, well maintained or poorly treated and properly or marginally set up. Operators may be accomplished craftsmen or newly trained employees without any experience. And, of course, you face a wide range of possibilities between any of these extremes.
All these situations add up to a vast number of possible product/processing combinations. For this reason, it is impossible to recommend any one of the 12 squeegee types without analyzing the appropriate processing variables. On the other hand, it is possible to correlate the 12 squeegee types with the general functions of the squeegee.
Note that besides the previously mentioned variables, the squeegee also has an attribute that is difficult to quantify: resistance to abrasion and chemicals. No standards or tests exist to evaluate this attribute. However, it is strongly recommend that you document the performance of your squeegee materials and evaluate them on the basis of actual production.