Pad Printing

Pet-peevish clichés are notorious for using a lot of words to say very little, overstaying their welcome and, before long, losing any significance they may once have possessed. However, there is one in existence that uses very little space (and ink) to say a lot, is far from exhausting its possibilities, and lends great significance to previously lifeless items. This cliché is imperative to a process that’s anything but: pad printing.

“Just as a cliché is a phrase that is used over and over, so too is a printing plate something that can be used repeatedly without being worn out,” says Annette Sharon, Pad Print Machinery of Vermont. A pad printing cliché, or plate, helps us to tell time, type coherent emails, and phone home on the first try, in addition to enabling embellishers to customize minute and unusual substrates such as guitar picks, buttons and golf balls. 

Big news in a small package

With minimal space requirements and start-up costs, pad printing is commonly regarded as a perfect add-on offering to screen printing, embroidery and other primary embellishment techniques. But with the increasing amount and versatility of interesting, smaller substrates, many are optimistic about its emergence as a stand-alone decoration discipline.

“I think you could start your own business,” Janet Gould of Imprintor suggests. “A lot of people are going out to schools, churches, city governments and getting in on events.”

While it has some limitations, such as substrate size and single-purpose clichés as opposed to reclaimable screens, Gould believes that pad printing could realistically produce enough volume for a decorator to deem it his or her sole offering.

“Pad printing is designed for small jobs, so if a customer needs fifty or a hundred, you can do that very easily and keep the job in-house instead of having to farm it out,” Gould remarks. “You can also do your own promotional items much more cost-effectively. There are so many options of things to print on.”

Consistent with that sentiment, Sharon not only sees pad printing as a compatible technique, but as one that’s often preferable to any other.

“In some instances pad printing is the marking technology of choice either because the per-print price is so competitive or the substrate can’t be printed with any other method,” she comments. “Some shops specialize in pad printing because of how easy it is to print large quantities of a particular item. Pad printing machines are also well suited for automation add-ons including conveyors, dryers and multiple marking stations.”

Because of the limited ink deposits, pad printing may never rival screen printing when it comes to promotional-apparel decoration but, for that same reason, it surpasses screen printing when garment decoration gets detailed: “On wearables, pad printing can get into places other methods can’t—on the waistband of blue jeans, across the seams of pockets on T-shirts, or on the crease where the crown and bill meet on a baseball cap,” Sharon explains. “More and more tag-less labeling of T-shirts and undergarments is being done with pad printing, precisely because it uses so little ink.”

How’d they get that on there?

The pad printing process starts with the cliché’s production, using a plate coated in photo-sensitive emulsion and, much like with screen printing, creating a photopositive image.

“Placethe film positive on top of the clichéin an exposure unit,and expose for a specified time period depending on your application,” explains Bobby Dyer, ERB Industries.

Once the non-image area goes through the first round of exposure, the plate is immersed in a baptism of sorts: “A water or alcohol developing solution is used to etch the image into the plate’s surface to a depth of just microns,” says Sharon.

The next round of exposure involves applying a screen tint film (similar to a mesh) to the image area and burning it into the cliché to control the ink deposit once printing commences.

“The screen is giving it texture to hold the ink,” Gould states.

The tint is then removed, and the cliché is washed, dried and exposed a final time in order to harden the plate and insure the microscopic design detail that pad printing makes possible. 

After creation of the cliché, the prepared plate is placed on the pad-printing machine, and the fun begins. “The ink cup slides back and forth over the etched artwork, leaving ink behind in the image,” Sharon reports. “The pad then lifts, moves over to the cliché, comes down and picks up the ink, lifts, then moves over to above the substrate, and descends to print on the item.”

The ink-to-substrate part of the printing can be altered by several factors, such as the use of a manual versus an automatic pad-printing machine, as well as the number of colors involved in the job.

“Multi-color pad print jobs use a machine with multiple pads,” comments Sharon. “Each pad, and its corresponding ink cup, is dedicated to one color. For example, if you are printing athree-color logo, the part is shuttled down the line of pads with a conveyer that stops it precisely in the right place to receive the next color.”

Full-process CMYK jobs work the same way, according to Sharon, who also discusses the different amounts of thinner and hardener that must be added to the colors to control the ink-drying time when printing any multicolor image.

Inkcredible options

Possibly the biggest variable involved in pad printing is the ink, with choices in color, type and, most fundamentally, application method: “An open inkwell uses a doctor blade to carry the ink over the etched image and clears the excess ink off of the cliché,” says Dyer. “An inverted magnetic cup—known as the closed cup—carries the ink over the etched image, performing the same task as the doctor blade. In recent years, this technology has been improved and more widely used due to environmental concerns. The closed cup provides hours of maintenance-free operation without any odor or exposing ink to environmental conditions in a factory setting.”

Glass, metal, plastic, fabric—the substrates available to pad printers are limitless, but must be matched to a corresponding ink, all sources emphasize.

“Inks are available in any color imaginable and in series specific to the type of substrate to be printed on,” Dyer explains. “Different materials react differently to the various elements in the ink. For example, you would not use a plastic ink on a metal substrate.”

Perhaps the most essential ink-matching task involves a very unique pad printing application: “There are edible inks as well that are printed onto food products,” says Dyer.

While pad printing inks are chemically similar to other types of product-marking inks, they are uniquely designed to dry quickly and adhere to the range of available substrates, according to Sharon, who also comments on the many ink-related advantages: “Because pad printing transfers the ink image from the plate to the substrate, only a few microns of ink are needed to print an image,” she states. “Likewise, the minimal amount of ink required in the pad-printing process allows for extremely fine and precise images, making it ideal for industrial uses, product marking and decorating. Some types of ink we carry can be post treated to create an extremely weatherproof, dishwasher proof and pocket proof printed image.”

Most commonly employed to print hard-to-otherwise-reach areas, microscopically small substrates, and everyday items such as keyboards, cell phones and dashboards, pad prints of greater proportions, such as for basketballs and wheelbarrows, are proof of the possibilities.

“In time, technology will allow us to imprint on larger and largersubstrates,” says Dyer.

To that, Sharon adds that, in spite of ink-cup and pad-size limitations, if you can get the part onto the machine, you can print an image on it. “Our customer base is extremely varied,” Sharon states. “Every week someone is sending in something new and different for our technicians to figure out how to print on. The biggies include car parts, appliance panels, metal and plastic tanks for liquids, snowboards and even satellite dishes.”

Small to large, practical to promotional, add-on or dedicated decorating service, pad printing’s precision and flexibility pick up where other services leave off and, according to Gould, “It’s just endless ideas.”