I sometimes use an abrasive grit blaster at work. It does the same
thing on carborundum grit, but at least in my case it's static
electricity causing the glow. The charge can and does build up to the
point where the rubber gloves on the cabinet break down and you get a
nasty static shock. I have seen it jump at least 3/8" of an inch to
anything grounded. This usually only happens in fairly dry weather on
this machine. Our plant air is also very dry as it all goes through a
aftercooler and chiller drier before being piped around the building.
The dry air probably increases the buildup of charge. If somebody took
the time to run a ground wire to the gun body on our machine this
probably wouldn't have to happen...