Received quickly, at a great price, this is what you use to weld Stainless Steel 30x 304 316 321 TIG exhaust or any use case where you don't want to run a backflush to protect against carbide buildup from the backside. I mix it with heat, which you can buy at any auto shop, so the fuel doesn't freeze. It is methanol and it is recommended to mix with sun flux. Make a paste out of it, runny, like the consistency of olive oil, not very runny but not thick like toothpaste. It will become hard after you mix it. You just need to add more methanol or heat to dilute it. If you have extra ones, just save them. It will dry and you can just heat it up and thin it again. I use an acid brush. Works well. Make sure it is completely dry before welding.