Answers to frequently-asked questions
If the blade height is not uniform across the screen, you might find one side or corner of your print is out of registration. Maladjusting the platen level to compensate for the poor printing might even ruin a well-designed automatic press.
Instead of pitching the blade, why not resharpen it? Squeegee sharpeners (ranging from $400 wheel-type sharpening kits to 16-ft-long automatic belt-type mega-machines that will do everything, including help you apply for a second mortgage) can remove a thin layer from an 80- or 90-durometer squeegee blade and restore a perfect edge. Many printers use an abrader wheel for softer durometer squeegees. An automated machine with a special blade-holding device is also available.
One distortion that sharpeners cannot correct is lateral warping or meandering of the blade from left to right. Such twisting is probably due to improper care of the tool.
How Long Should the Squeegee Be?
Squeegee length should fit the image being printed. Choose a blade that extends about 1 in. beyond each side of the widest section of the design.
The squeegee also needs to fit within the screen. If the end of the blade is too close to the frame, the ends of the squeegee will exert excess pressure on the stencil and cause pinholes. There should be at least 2 in. of free space between the image and the screen frame. For example, if the width inside your frame is 22 in., your squeegee should not be longer than 18 in.
Most squeegee manufacturers recommend rounding the sharp ends of every squeegee blade. A rounded end is less likely to dig into and fatigue the stencil, resulting in a band of pinholes.
What is a Good Angle of Attack?
If you hold your squeegee at 90° to the mesh, you will be unable to muster enough pressure to compress the ink into the screen. Conversely, if you reduce the blade angle so the blade is too close to the screen, you will push too much ink through the mesh.
Most printers find that pulling the squeegee at 15-20° off the vertical ensures an even deposit of ink. The setting of the exact angle depends in part on the squeegee's profile and durometer.
If you are printing puff, glitter, or a thick undercoat with a bullnose-profile squeegee, the angle will make little difference, since a round edge is, well, round on all sides.
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