User login

The Secrets of Successful Pad Printing

(February 2003) posted on Wed Mar 12, 2003

This discussion expains how you can make the most of your machine by considering all aspects of production, from climate and press location to substrate readiness and ink preparation.

click an image below to view slideshow

By Carol Swift, Peter Kiddell

Flaming Flaming is generally thought of as a means of pretreating polypropylene or polyethylene to increase its surface energy for improved ink adhesion. But flames can also be used as a post-printing method for flash drying conventional pad-printing inks. In certain applications, flaming not only provides the fastest drying solution, but actually promotes ink adhesion better than other alternatives.


One example is when you are pad printing on certain engineered plastics. Flame treatment creates a bond between the ink and substrate that would be minimal if another drying method were employed. The dyes in sublimation inks can also be transferred into certain copolymer plastics with the careful use of flaming. Should you decide to use flame drying, make sure you've eliminated all potential hazards by incorporating the proper safety devices and cutoff systems.


Other, more specialized, drying systems may also be called for, depending on the application. Sensitive substrates might require a static oven that applies a very controlled heat level without air movement. Newer ultra-violet (UV) curing pad-printing inks require a UV dryer to provide the proper wavelengths of energy to achieve a cured state. And when pad printing is used to apply frit-based colors for glass and ceramic decorating, a high-temperature kiln or lehr is required to "fire" the inks to the substrate and form a permanent coating.


The broader perspective


Pad printing can be a very effective and efficient decorating method if you consider all the components of the process and the way they work together. The ideal system requires more than just the right machinery; it requires knowledge of the variables that influence printing success and the means to control those variables. By following the suggestions presented here, you'll be closer to achieving that ideal system and boosting the quality and consistency of your products, as well as the productivity of your printing operation. Gloves and Personal Safety


One important facet of pad-printing production that gets little recognition is worker safety, particularly as it relates to the use of protective gloves. Pad printing uses volatile, often aggressive solvents and inks that contain highly reactive resins. Skin contact with these materials can lead to their absorption into the user's bloodstream, which may cause adverse health effects in the long run. If nothing else, users repeatedly exposed to these chemicals may become highly sensitized to them, so much that they are unable to work with or near particular inks or solvents.

Most pad-press operators, if they use gloves at all, use basic household gloves of thin latex or vinyl. While these gloves may be suitable for warding off occasional drips and splashes, they are a poor line of defense against heavy coverage or complete immersion in pad-printing inks and solvents. Pad-printing solvents, in particular, can destroy these household gloves in a very short time.

No single glove material (or combination of glove materials) provides unlimited resistance to all chemicals used in pad printing. Any glove material will eventually fail to protect the wearer from aggressive chemicals, which can find their way to the user's skin in one of three ways:


*Permeation: The process by which a chemical agent migrates through the protec tive glove at a molecular level.


Penetration: The bulk flow of the chemical agent through closures, pores, seams, pinholes, or other imperfections in the protective glove.


*Degradation: A damaging change in one or more physical properties of the pro tective glove as a result of exposure to a chemical agent.


When choosing work gloves for your operation, seek help from a glove supplier. You will need to inform the supplier of all the chemicals you use. You may get assistance from you ink suppliers, whose Material Safety Data Sheets should indicate compatible glove materials. Good working practices must be part of your glove-use policy. Minimizing contact with harmful chemicals is much more effective than only relying on a barrier in the form of gloves.


Did you enjoy this article? Click here to subscribe to the magazine.