I may have identified the (non-stunt version) slime blower gloves from GB II!
They appear to be "Neoprene Heat Gloves" for grilling. They have the same odd cracked texture that extends from the finger tips to the wrist, and the glossy/semi-gloss cuffs extend right up to the bottoms of the elbow pads on my uniform (like the film gloves do).
The only real hiccup is the logo on the cuffs. A couple companies seem to offer these or similar style gloves, and they all seem to have logos on them. Stripping off the logo also strips off the gloss finish of the cuff. Once the weather warms up though, I'm going experiment with covering up the logos with either a spray-on rubber or Krylon Fusion.
The palms and cuffs are the same shade of black, but the palms sometimes take on a lighter appearance depending on lighting (which I believe is what we see in the films... and you can see in my photo).
The cheapest I had found these gloves so far was through Big Poppa Smokers ($15.00). They seem to also have a more expensive version with removable liners, but I went with the cheaper pair, so I can't really say if there are any other differences between the two.