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PADPRINT
NOTEBOOK Useful Tips & Information © ITW Trans Tech An ITW Decorating Company |
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Maurice Caporali
ITW Trans Tech Print Lab Technician
& Applications Specialist
Tips From the Pros:
Watch Those Viscosity Variables
VISCOSITY is defined as the degree of resistance to flow in liquids. Honey is a high-viscosity liquid; water has low viscosity. As it applies to mixing ink, the controlling factor in ink viscosity is how much or how little thinner is added. Here are a few pointers about using thinners which I recommend you keep in mind when opening that next can of ink:
1.
Always mix by weight–
(not volume) by adding thinner at a percentage of the original ink weight. Most are mixed at a ratio from ten to twenty percent by weight. The amount will vary, depending on desired viscosity.
2.
All inks are not equal.
Each individual ink, even each color, has a slightly different weight due to its specific pigments. If you think you may need to reference this information later, write it down. It will avoid guesswork on the next job.
3.
Don’t over-thin.
Important: don’t over-thin your ink, even if it looks and pours OK, excessive thinning may shift the color. To be sure, always check the printed color against the master color swatch.
4.
Thinner buys limited time.
Remember: thinner buys you a little time by extending the window of usability, but that window is not unlimited. Beware of trying to stretch your ink too far; it may affect the final print quality.
5.
Check the variables.
A number of variable factors will influence that time limit:
• Choice of Thinner Speed– For example, with Type P Ink, B Thinner is faster, VD is medium, and BGA is slower. This speed refers to the time required for the solvent to “flash-off” or evaporate from the surface of the pad, cliché or printed part. NOTE: this can also be slowed down, if desired, by the addition of retarder.
Pad Blowers Are Smart Accessories
• Pad Blower Usage–
This standard accessory will help shorten the flash-off time by speeding the evaporation of the solvent thinner from the surface of the pad. Our adjustable units are recommended for nearly every application.
• Environmental Conditions–
The ambient room temperature and humidity must be controlled. Any wide swings in exterior weather or air conditioning may also affect your pad printing operation’s success. For example, ink flashes off more slowly in a humid environment.
Give Your Clichés Professor Tom's Grey Scale Test
• Cliché Depth–
The proper etch depth can make the difference between a successful image transfer and a series of frustrating trial-and-error attempts. A cliché that is etched too deep will deposit too much ink on the pad, making it unable to release it entirely. The result is a residual image left on the pad after transfer.
The opposite problem is created when an etch is too shallow. The ink layer in the cliché is so thin that it evaporates too quickly and then sticks to the plate. The transfer is less than optimum, resulting in a weak image and dried ink residue remaining in the cliché. With the right etch depth these issues can be controlled.
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