I didn't even know it was possible to screen print leather. Although it makes sense. I think Fluid or Solmu might know of an ink that might work?
I know that it's possible (because I've seen it done - worked well too, was made into custom leather journals/diaries). Unfortunately that's about where my knowledge ends. I haven't printed on leather myself and didn't discuss how it was done.
I'd speculate the printer used a normal paper ink and a 110t (280) mesh, but I'm not at all sure. Hopefully someone else will have specifics.
you can do it, you add a nylon bonding agent, just like printing on a nylon jacket, you can get it from a few different companies. do a few tests, and when you are ready for production make sure you mix enough of whatever color you are doing.
honestly i have never printed on leather cause of my own personal reasons, but i know it works like that, like always do a test and write down all your findings for your own files
Wow, I really have to become an expert on this fast. A game company really liked the pin-up style art we are using for a shirt, and now want it printed on the back of a leather (or fake leather) bomber jacket.
Many years ago I screenprinted leather cases, if I'm remembering correctly we used a sign ink and a medium-high mesh count. The ink basically sits on the surface and leather is smooth so it's more like sign printing than textile printing. I remember it mostly because it was a pain in the butt and the first ones were bad because we put too much ink down.
You're probably going to want to use an airdry ink of some sort. You may want to call NazDar SourceOne -- they manufacture inks for all types of applications.
If you pull off cmyk on leather (vinyl) I gotta see it, but I wonder if you might be better off doing the image in index. The process is alot more forgiving and consistant especially if you have a couple extra heads to spare for extra colors.
leather? 
