Why are you needing to paint the rubber?  

Any "paint" you could use would be a type of rubber (technically an "elastomer") in its own right, in order to flex with the substrate rubber and maintain adhesion.

Can you not color the rubber to achieve what you want?  Use an EPDM compound, or Santoprene, among other polymers they hold up well to steam at 180 C.  

btrueblood:

thanks for the reply.  for specific purposes, we need to assign a unique number to each piece.  at the end of each day, these, along with other items, would be autoclaved, so as to not cross-contaminate materials.  thus, the paint must be able to withstand the necessary conditions for sanitization.

best,
g

Well then, instead of thinking "paint", think "ink" - i.e. you want to apply a pigment that either sticks to, or is absorbed into, the base rubber.  If the base color of the rubber is black, use a UV-fluorescent ink.

thanks btrueblood.

any recommendations as to a type and supplier?

regards,
g

what about lasermarking?

TTFN

gkar,

How long or how many cycles do you want the marking to survive?  We've had pretty good luck in the past marking parts in hot water/steam service using plain old permanent ink markers.  Of course, these are a light-colored rubber part, and black ink shows up nicely, and we take care to mark areas not subject to abrasion (although showing where abrasion is occurring is another great use for the technique).

Beyond that, I would talk to your supplier about their suggestions.