[rugman59]

Next time you wear out a batch of Park solution or it gets contaminated with oil, don't toss it out.
Put it in a homer bucket with a screw on lid and keep it handy.
When you get some fresh steel to carve on and it has all that scale that looks like black paint on it, just drop it into the bucket overnight. The phosphoric acid will knock that stuff right off. A light hand wire brush with rinse and it's gone.
I don't know for sure how well it would do to clean flux from a brazed part, but I've read it works.
That being said, I did have a freshly brazed steel part fall off after using phosphoric for Parking, but I'm fairly positive that was chiddy brazing by me.:tongue:

 

[Korn]

That is a great tip, the mill scale is hard to remove with a sanding disc. I always remove the scale before TIG welding, makes a much cleaner weld.

 

[fizzlooney]

cleaning

pool acid ,HCl ,works well on rust also, 50% solution. eats the rust but leaves the iron alone.. cheap also get it at home depot about 7 bucks a gallon

 

[glassmountains]

pool acid ,HCl ,works well on rust also, 50% solution. eats the rust but leaves the iron alone.. cheap also get it at home depot about 7 bucks a gallon

Not sure about using HCI. Won't that cause hydrogen embrittlement?

 

[fizzlooney]

hydrogen

Only applies to high strength steels under stress, like a fastener torqued to a high load. your run of the mill gun parts are fine