The rating that matters is arc thermal performance value (ATPV), expressed in cal/cm², which must exceed the incident energy of the work being done.
Welding jackets are the standard outer layer — leather for heavy spatter and radiant heat, FR cotton for lighter work and better breathability. Leather jackets protect against spatter and heat but are heavy, hot and stiff; FR cotton jackets are lighter and more comfortable but will not stop heavy spatter or resist radiant heat for long.
Sleeves, capes, bibs and aprons cover the specific areas that get exposed. Leather sleeves protect the forearms during overhead and out-of-position work; a bib apron protects the torso and lap when welding seated or kneeling; a cape protects the shoulders and upper chest. These are the pieces that get worn through first and replaced most often.
FR shirts, pants, coveralls and sweatshirts are the base layer for shop work. The material must be inherently FR or durably treated — untreated cotton will burn, and synthetic fabrics melt onto skin, which is worse than burning. Washing instructions matter: some FR treatments are removed by detergent residue or fabric softener.
Leather aprons and split-leg bibs are used for heavy spatter work and for protection when the arc is close to the body. They are the practical choice for stick welding in tight positions and for any work where spatter falls rather than sprays.
