Pad Printing: How to Handle Temperature Swings

How to Handle Temperature Swings in Pad Printing

TOO HOT:

In a warm atmosphere, solvents in the ink will evaporate very quickly. The ink will dry on the pad and only partially deposit onto the substrate, if at all. Here are some ways you can resolve this problem:

Speed up the forward travel of the pad stroke.
Use a different thinner/retarder mix. (I always start with a mix of 25% retarder to 75% thinner, then modify the ratio according to the results. In warm shop, I would increase the amount of retarder.)
Bring down the ambient temperature. (I know this sounds easier sald than done, but can you move the press farther away from the conveyor dryer? Can you move it away from direct sunlight?)

TOO COLD:

If the atmosphere is too cold, the solvents won't evaporate quickly enough. As a result, the ink won't become tacky enough between pickup and laydown to transfer completely to the substrate. You may see patchy prints (as in a shop that's too warm), occasional feathering, prints that vary in density, or even pickup of previous colours in rnulticolour work. The pad picks up some of the ink from previously printed colours and brings it back to the cliche. Over a period of time, it will actually cause the ink in the ink well to change colour. Here are some things you can try:

Slow down the forward travel of the pad stroke.
Select a faster-drying thinner.
Use a hair dryer, normally pointed at the pad as it travels forward after ink pickup, to speed up the evaporation of the solvent.
Raise the ambient temperature.

I hear you ask, "But how do I know if the ink is drying too quickly or not quickly enough?" The easiest way to check is to gently run the tip of your finger over the pad after the print stroke is finished. If the Ink is drying quickly, none will come off on your finger. If the ink is not drying quickly enough, the ink will smudge. (Of course, wear protective gloves when you do this, Ink and solvent contact with the skin must always be kept to an absolute minimum.)

Introduction .. Upgrades in inks and pads have helped make the process more controllable. Better machine design has enabled better consistency in setting and (more importantly) easily adjusting each phase of the print cycle..
Adding & Using Pad Printing Solvents In most cases, pad printing requires you to add solvents to your ink regularly.
Controlling Ink Delivery Many of the problems printers experience can be traced back to solvent evaporation in the ink well.
Controlling Temperature & Airflow The more stable the environment, the more effectively you can control the process.
Controlling Humidity and Static Another troubleshooting step that some printers overlook is how fast the press operates.
Controlling the Variables We've looked at how ambient conditions can affect your print quality, but these aren't the only variablesin the pad-printing process.
How to Handle Temperature Swings In a warm atmosphere, solvents in the ink will evaporate very quickly.