Most shop welders show up in a Carhartt FR jacket or a Lincoln welding jacket and a polyester base layer. Spark hits the jacket and bounces off, no problem. Spark goes through a seam, lands on the polyester, and the polyester melts to your skin. That's the burn that puts a guy in the ER.
FR isn't just the outer layer. The base layer matters more than the jacket because the base layer is touching your skin.
Carhartt FRB001 long-sleeve henley is the standard. NFPA 2112 rated, HRC 2. About $60. We sell more of these than any other welding base layer.
Bulwark Excel FR ComforTouch tee is the lighter summer option. Same NFPA 2112 cert, lighter weight, better for shop welding in July when you'd otherwise just wear cotton.
Cotton t-shirts are not FR. They burn slower than polyester but they still burn, and the GC or shop foreman who tells you cotton is FR is wrong. The reason cotton is sometimes-okay is it's better than polyester. It is not better than actual FR cotton.
Outer layer: Carhartt FR Heavyweight Sweatshirt for shop, Lincoln Electric K2989 jacket for stick or MIG, Steiner Weldlite split-leather jacket for heavier overhead work. The lighter Tillman 6230 cape sleeve is for vertical and overhead where you don't need the bib. Pure leather welding jackets are still the best bet for stick at amperage; FR cotton is fine for MIG and TIG.
Pants: Carhartt FR Rigby pants or Bulwark FR work pants. Avoid synthetic blends, even FR-treated. NFPA 2112 cotton FR pants only.
"Spark goes through a seam, lands on the polyester, and the polyester melts to your skin."
Boots: 8-inch leather, no laces if you can manage it. The Thorogood 804-4910 8-inch GEN-flex2 with the Vibram lug, or the Red Wing 2406. Kevlar laces if you're keeping laces — sparks burn through cotton laces like nothing. Avoid metallic eyelets if you can — the slag finds them. Internal MetGuard if you're shop welding heavy plate where dropped slag is a real concern.
Boot covers — Tillman split-leather spats — go over the boot for any kind of overhead work. They cost $40 and save the boot leather. Most welders I know own a pair.
Gloves: this depends on the process. Stick — a heavy gauntlet like the Tillman 875 elkskin or a Lincoln K2980. MIG — a medium-weight Tillman 1338 goatskin or the Black Stallion 750. TIG — a soft, thin glove like the Tillman 1488 kidskin so you can feel the rod. Most welders carry all three. The TIG glove is shocking the first time you try to weld in a stick gauntlet.
Helmet: Lincoln Viking 3350 or Miller Digital Elite if you can afford it. ESAB Sentinel A50 for the guys who like the futuristic look. Auto-darkening, variable shade. The Harbor Freight $40 hood works for hobby welding; for production it's not enough. We stock Lincoln, Miller, and a couple ESAB models.
Bandana under the helmet: a flame-resistant welder's beanie like the Comeaux 1000. Cotton is acceptable here; treated FR is better. A regular cotton ball cap will catch a spark and you'll feel it.
Earplugs and respirator: HEPA filter under the hood for stainless welding (chromium fumes are real), regular respirator for galvanized (zinc fume fever is real). The 3M 8233 P100 disposable is fine for general MIG. Stainless gets a 3M 6502QL with cartridges.
FR is a system. The jacket isn't enough. The shirt under it has to be FR too.