browning

[yip]

  i don't want to be rude and  igorant but is it true that urine to accelerate rust?

[Dave B]

I had heard that Hersel House has students  when they have to go  to water down the barrels out back of the shope that he is aging. The salts from urine would cause rusting no question. I perfer to use Jim Cambers laurel mt browning, it dosent smell as bad as old urine.

[satwel]

According to a book I bought many years ago that covered the history of the Remington Arms Company, Eliphalet Remington used a solution of iron filings and urine to brown the barrels of the first rifles he built in the early 1800's.

Also, a friend of mine, who is a prominent black powder gunsmith, told me that to match the patina of an antique muzzleloader he will sometimes heat a newly-made replacement part with a propane torch and then dunk it in urine.

[Goo]

I thought urine was more like ammonia than acidic

[parve]

I thought urine was more like ammonia than acidic

It is, the hydrolysis of urea results in ammonia, bicarbonate, and hydroxide ions. This causes the pH to rise to ~9.2 and yields ammonia concentrations upwards of 10 g/L. I assume the main driver of urine rusting steel is the high ionic strength, depending on an individual's hydration level and diet it can reach the same order of magnitude as seawater. All of my books are currently packed up but I know in one of them there's a recipe for Hacker Martin's browning solution, which calls for chamber lye (old urine). Utilizing urine for its salt content makes sense if you have other uses for the salt in your kitchen.

[Scota4570]

Lots of things will promote rusting.  Anything that attracts water will work.  Urine is smelly and nasty, not for me.  I have seen on line demonstrations of rust bluing using hydrogen peroxide and table salt solution.  IT may be a more user friendly option for the experimenter. 

I bought a quart of LMF.  It should last a while.  It works fine.