your advice on repairing a crack on sharktooth grill

For crack repair on plastic parts, my body shop owner did a repair of the rear interior side plastic panel crack.. There can't be any missing parts, just a crack. He used a two part product, a liquid and a black powder. He poured the powder on the crack then swirled the liquid onto the powder and worked it into the crack. It seeps into crack and supposedly makes it as strong a the original plastic. I didn't get the name of the material, but it worked well.