The Company - Pad Printing ExplainedThe History of the Pad Printing Process
Origin of the process
Pad printing was originally developed and used in the Swiss watch industry to print watch dials and car instrument dials using manually operated machines with pads made from gelatine, and using slow drying oil based ink.
In the late 1960s the process was further developed in Germany with the introduction of silicone rubber pads and mechanical machines; with the help of Wiederhold (now Coates Screen, part of Sun Chemicals) a range of pad printing inks were developed to allow the process to print onto a wide range of products and materials.
Pad printing is an indirect photogravure process. An image is etched into a flat printing plate and ink is flooded and doctored across the surface leaving ink only in the etch. A silicone rubber pad then presses down onto the etched plate and picks up the ink, which due to solvent evaporation has become tacky.
The image is now on the surface of the silicone pad. Silicone rubber does not allow ink to penetrate its surface and therefore when the pad presses down onto the product to be printed it releases the ink as a clean film. The range of inks and solvents used enable the inks to adhere to the surface after releasing the ink the pad is then clean and free to repeat the process.
Because such a wide range of inks are available almost any material can be printed and due to the flexibility of the silicone rubber pads uneven, curved and awkward shaped surfaces can be printed. As the ink is quick drying, pad printing is capable of 'wet on wet' printing and high quality multicolour designs can easily be achieved including four colour process.
The more recent development of closed cup machines has made the process 'cleaner' and enabled the process to become more user friendly and automated.