Just using 5# Sodium Hydroxide + 2.5# KNO3 (any nitrate will work potassium or Sodium, don't use ammonium) per gallon of water, there are many recipies out there, some have a little Potassium Nitrite as well if you can actually find that. I have good results from 270-285 on most steels. You will go through a learning curve, be careful and wear your PPE. Stick your finger in that solution when it's boiling and you will see bone instantly

Monitor your boiling point, if it boils too low just give it some time for the water to boil off and the boiling point will increase (be extremely carful adding water to hot solution) it will spatter at you like water in a deep fryer except this stuff will severely burn you even when it is cold, I use ice cubes when my boiling point starts to get too high, much safer. I made a trip stateside recently and got some extra's to throw in my bath. If you are serious give me a shout next month and I'll show you how it's done.
People look at you real funny when you go around asking for Nitrates, you need to find a source where you are not asking for Potassium Nitrate but getting Pure Potassium Nitrate if you know what I mean