Had auto shop uniforms in the past. They seemd to be flame retardant and also resistant to battery acid. I am thinking most of their blue collar uniforms are FR and acid resistant. I believe they are chemical cleaned. They could get most any stain out except RTV. Never remember a problem with grit in the pockets.
I worked at a factory that made large air filter products. They took cotton thru a pool of ? to make it flame retardant.
