I find Phospheric Prep and Etch--a phosphoric acid solution, does a good
job ot taking rust off my grill. I have the grill in pieces and I'm very
much tempted to dilute the solution and let it nibble at the grill in a
large plastic tub over a few days. I suppose my big problem is how I
should dispose of it. I know it etches concrete so I don't suppose it
should go down the drain.
Outside of not doing this at all, the only idea I have is to let the
solution evaporate down over days and then take it to a hazardous waste
disposal facility; the initial, diluted quantity is going to be too much to
transport elegantly. I just assume that the water will evaporate out over
time. Does anybody have experience with this?
It's probably best to make sure it gets diluted rather than having
a slug of it stand in the plumbing - which if you have copper DWV, could
be a problem. Phosphoric acid strong enough to eat rust will also
eat copper - not very fast, but still...
I just flush it a couple of times.
[IIRC, coca cola has trace quantities of phosphoric acid sufficient
to corrode a copper penny.]
Age and Treachery will Triumph over Youth and Skill
Unless you're talking about several pounds of concentrated acid, I'd
just rinse it down the drain with plenty of water. Large quantities you
could neutralize with limestone, like you spread on your lawn, or
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