I bought a cut-to-fit thick rubber mat for my 08 long bed. When I installed it, I noticed the black pigment rubbing off on my hands and clothes. I removed it, washed it, let it dry , and re-installed. Same problem.
Is there something I can coat the mat with to prevent this problem.

Some rubber products need a period of time where it is exposed to air and sunlight to put a cure to the material. If not cured, I'd suggest a cleaning with a product like Armor All or its ilk.
You might also check the FAQ at the manufacturer's site. I'm sure they know how to deal with your problem.
Let us know what your figure out, okay?
Red

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2005 Titan KC SE, Helwig, True-Track, ARE MX Canopy

Who made the mat?