People do it, straightening a length of MIG wire and using it as filler. On mild steel for non-critical work it produces an acceptable weld.
The reservations are real: MIG wire is copper-coated, which can introduce copper into a TIG pool, and its deoxidiser content is formulated for transfer through an arc rather than for dipping into a pool. Proper TIG rod is inexpensive, and using it removes a variable from every weld.
The questions welders ask
What about stainless MIG wire for TIG?
The same reasoning applies more strongly. Stainless welds are judged on corrosion resistance as well as strength, and getting the alloy right matters. Buy 308L or 316L rod for stainless TIG rather than improvising from spool wire.
Last reviewed 2026-08-14