Any of you use this? https://www.rustoleum.com/product-c...alants/clean-maintain/phosphoric-acid-cleaner I am wondering if anyone knows it's potency?
Industrial strength phosphoric is 85% and page two of their product MSDS says 25-50% phosphoric, while page three says "less than 40%" so 0.85 x 0.39 = 33% phosphoric acid. It also has 1% hydrochloric acid which may be a hassle.
I am looking at it for a cleaner to prep surfaces for patina... Hydrochloric probably will react to bronze... Interesting there are different cut sheets on this stuff. The first one I read said it was a proprietary amount and didn't mention the hydracloric.
I buy mine from a local cleaning supplies place that makes their own formulations, they have all the acids at industrial strength. 85% phosphoric acid was cheaper by the litre from them than the 30% strength rust neutralizer from an auto parts store.
It's at Cairns, Australia, about an hour's drive from Atherton.....Coxen Cleaning supplies. They have nitric, sulphuric, hydrochloric, phosphoric, and hydrofluoric (not for sale to the public).
Damn! I was just in cairns & atherton a few months ago in march. Not that the airline bastards would have let me take acid home with me to the states haha. Would be nice to find a place in the states New Jersey or CT to buy it.
I use phosphoric all the time to remove rust from old iron, not this brand. It is a great rust remover/inhibitor. With iron it forms an iron phosphate coating. Years back it was used in auto paint prep ... Oxpho (or something like that). I typically use Klean Strip Concrete & Metal Prep, I get it at Home Depot (from memory 35%ish). Or, if I want some without the 40 min trip each way ... I head to our local farm store and get Dairy Milkstone cleaner. This is 25% 0r 30%, but does have some other chelating agents. No clue how the phos reacts to bronze.
What about nitric acid? I've wanted to try it for gold extraction for ages but it doesn't appear easy to find.
Ok, I got some 75%... Probably on some government list, that I wasn't on before... What kind of safety equipment do I need? Space suite? Rubber gloves?
https://www.ccohs.ca/oshanswers/chemicals/chem_profiles/phosphoric.html Looks like nitrile gloves will do. I have a face shield, but no chemical goggles, hmm.
Always, always, always ... add the acid to water when diluting. Never add the water to the acid when diluting.
Gloves and face shield are fine for phosphoric acid. Chemical splash goggles are highly preferred if you can buy some, but a face shield is better than nothing. Phosphoric is nice because it's non-fuming, unlike hydrochloric or ntiric, so you shouldn't get any nasty gases. Here's a handy resource when working with chemicals: the Ansell Chemical Resistance Guide https://ehs.unc.edu/files/2015/09/Ansell_8thEditionChemicalResistanceGuide.pdf It shows how different types of gloves fare against a wide range of chemicals. For concentrated phosphoric, nitrile gloves are the best. (I prefer nitrile for everything, since it's possible to develop a latex allergy.) Short chemistry rant: And yes, always adding acid to water is great advice, and there's absolutely no reason not to do it that way. But the dangers of doing it the other way around are, in my opinion, a little exaggerated. I've seen several tests where water was dripped into concentrated acid with no splashing. But that doesn't mean it can't happen. Just keep doing your research before using any chemicals, and try not to be too scared of them. Just respect your chemicals, wear your safety gear, and have a plan for if something goes wrong. I'd recommend keeping a big box of baking soda nearby to neutralize any spills.
"Do what you oughter, add acid to water" That was the old saying I was taught. I can't say how important it is or is not, but it helps me remember the preferred method. Denis
