I'm setting up a shop and hot bluing is out of the question for a number of reasons. I've got a PVC pipe tank to hold hot water for rust bluing. Buying distilled/deionized water for every job seems a bit expensive and dumping rainwater down the drain after every job seems wasteful to me as well. So really 3 questions:
1. Does rainwater do the job as well as distilled?
2. Can the water be reused for the next job?
3. Is there a test, such as pH to tell when the water needs to be changed?
Opinions and guesses welcome. Please let me know when you're guessing, opining, and when you've got some hands on with this.
Thanks in advance.