Find out how to manipulate artwork and select the right equipment and consumables to pull off the project successfully.
By Linda Huff
The shape of the part isn't really a deciding factor when selecting an ink. As with all prints, the part's material composition dictates which ink will work best. Ink manufacturers have formulated an array of inks with specific properties that facilitate adhesion to virtually any substrate. Familiarize yourself with the materials on which you're printing, and ask your supplier to recommend an ink that will best adhere to the substrate and resist damage caused by abrasion.
Some materials, such as those in the polyolefin family, require surface treatment before printing. The options range from corona or flame treatments to simple ink additives. But if you're unsure of the material, ask your supplier to recommend an ink and test it for you. Make sure you send enough samples for your supplier to test several different inks. There may be more than one that will do the job. Post treatment procedures may also be required.
Additionally, be sure that your supplier can provide the ink in any color. Be aware that you will be charged extra for color matching than what you would normally pay for your supplier's standard line of colors. There are several universal systems of identifying color. Most suppliers can work with all of them. If needed, your supplier may be able to match to a wet sample, or even a printed sample, of the part.
Once you have selected the right ink for the job, make sure you use auxiliaries that are compatible with your production run. Pad-printing ink is available in one- and two-component formulations. One-component ink requires only a thinner, whereas two-component inks require both a hardener and thinner. Two-component inks usually have only one hardener of choice. However, the thinners required are available with different rates of evaporation. Thinner selection is based on the production environment. Identifying your machine speed, image size, facility temperature, and humidity will help to narrow the field of choice. Again, consult your supplier for assistance.
If you plan to use a two-component ink, make sure you are aware of the ink's curing time. There is a significant difference between drying and curing. Single-component inks can dry within seconds, whereas two-component inks can take as long as several days for the chemical curing process to complete. Allow for this time when preparing for production. If the temperature of the part changes significantly prior to curing, then the chemical process will stop and the part will have adhesion problems later on. You should allow the ink to fully cure before you package the part. Curing can be accelerated, but consult your supplier for the best options regarding your particular project.
Approaching the unusual
Accepting a strange or challenging pad-printing job can be a nerve-racking proposition. But if you take the time to understand the demands such jobs bring to the process, you'll save yourself time and money—and most of your hair. Correcting artwork distortion on your cliches, using the best pad for the image, selecting proper tooling and pad support, and bringing a compatible ink to press will help production run smoothly and leave you with plenty of hair to spare.
About the author
Linda Huff has eight years of experience in pad printing and consulting as consumables sales manager for Tampoprint International Corp., Vero Beach, FL, a manufacturer of pad-printing equipment and supplies.
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