Pad printing

 

Teca-Print AG is a manufacturer of pad printing machines in a town in north-eastern Switzerland. For the last year and a half, we have been using their machines to pad print onto our watch dials, and just last week I did a day of advanced training in their headquarters in Thayngen! Thayngen is a very small village about 20km north of Schaffhausen on the Swiss-German border. Pad printing is a dark art. Even after nearly two decades, the techniques, processes, and "know-how" for high quality pad printing are still heavily guarded and regulated.

High quality pad printing is like a dance, a perfect end result is the consequence of constant parameter tuning. The ink viscosity, the room humidity and temperature, the material of the dial being printed on, the surface finish, the pressure applied to the dial, the composition, hardness, age, and quality of the pad that is transferring the ink, the pigment size in the ink, the ratio of thinner to hardener, to ink pigment... the list goes on.

One example of how difficult and varied the parameters of printing can be is in the ‘pad’. Generally, pads are cone shaped and made from specific types of silicone with varying hardness’s. The specific shape of the pad has a large influence on the way the pad printing process behaves - flatter, less sharp cone shapes tend to have LESS distortion in the design that is being printed (imagine a square design getting distorted into a cushion shape, or a circle turning into an ellipse). On the other hand, sharper, pointier pads tend to be less susceptible to errors like smudging, ghost images or streaking in the print. Moreover, the type of silicone, and the hardness of the silicone are also variables that can be tuned. Some silicones have antistatic properties that work well with inks that print onto plastics, whereas other silicones work exceptionally well for types of inks that bond better to metals. The hardness of these silicones is also tuneable. Hard, stiff silicone is fantastic for reproducing the finest of details, hair-width lines, and font, but require a lot of pressure to work, which can damage the dials! Soft silicones are a great alternative for delicate parts that require printing but have the tendency to smudge or not be able to pick up very fine details.

To make things worse, Teca-Print stocks 2000 different sizes and shapes of pads, with 5 different silicone compositions and 5 different silicone hardness's! That's a very large selection to choose from! While I was at Teca-Print, I was being trained by a gentleman called Armin. Armin was the top applications engineer at Teca-Print, with 4 years of experience as the go-to guy for the leading Swiss pad printing machine manufacturer. He trained many people within the watchmaking industry, local within German speaking Switzerland, (think IWC), as well as the French speaking side, (think Swatch group, Richemont, LVMH, as well as... everyone else). Armin guided us with some tricky requests that we provided him, and produced some processes and tips that we will for sure take home! After a full day of training, just before we were due to go home, Armin disappeared into an Alibaba's-cave-like storeroom that contained every single pad printing supply that Teca-Print stocked... He emerged with a cheeky yet victorious smile and handed me a small package with a very specific looking silicone pad. "This one will work. I know for sure". Puzzled, I couldn't help but to ask, "How do you know!?" "Ah well, of all the pads we stock, shapes, sizes and colours, our neighbour in Schaffhausen, who prints all their dials in-house, uses this one, and only this one." Thank you Armin!