Simulating Rubber.

Front fork seals & handgrips?, we must be talking bikes here!
Try doing a coat in black and then dry brush over it with a slightly lighter shade.
Rubber, especially on tyres (tires) doesn't stay black too long, due to sunlight, dust etc, the lighter shade (black with a touch of light grey) will add depth to it, especially on convoluted fork seals.
All the best
Pete

Not just Bikes but rubber in general, the reason why I used bike parts as an example is because I am very familiar with them and love them.

Thanks, for the tips will try them on the next model.

What about using the plastic sheath from copper electrical wire, after having used a wire stripper to remove the copper? I've used it once or twice for general scratchbuilding for rubber hoses, etc. Hope this helps. :)

I read somewhere that a good way is to add blue to the black. I did it once on a set of small tires an it look pretty good. When I did that it also made it easy to do a wash and drybrush.

I use the MM flat balck with a little grey mixed in....