If I remember correctly, I picked up some Gordon's Stump killer. There were two varieties of Gordon's, one indicated it was 100% pure Potassium Nitrate, the other was Potassium Nitrate with some other ingredients. I used the 100% Gordon's. It seemed to work well on some pins and a trigger guard I nitre blued.
I used a propane burner a stainless pot I picked up at goodwill and a BBQ thermometer that registered 700 degrees. My thought at the time was I need to pick up a better thermometer that registers a bit higher temp.
A bit of a learning curve and I didn't do enough nitre bluing to gain good consistent results for the fire blue I was attempting to get. I did get some nice blue and blacks but it was inconsistent!
