Oxalic acid & bronze

I have just been doing this very job with white vinegar AKA acetic acid. It cost me £6 for 5l from my local Indian supermarket. It is quite slow but loosens the encrustations without making the bronze go pink. That being said, the vinegar is now very noticeably blue!
Cheers
Rum Run
 
I know that Phosphoric acid is available in fluids used to clean non ferrous electrical contactor equipment and motor commutators. It may work on bronze. By the way, Phosphoric acid is to be found in Coca Cola!! Yummy!!
 
Phosphoric acid works .... but at stronger dilutions than coke:-)

Muriatic Acid (Hydrochloric Acid) is much cheaper but also more aggressive to the bronze. I use a 5 part water to one part HCl .... but I don't know the concentration of the HCl in the bottle. Keep an eye on it and don't leave it in the solution longer than necessary to soften the fouling. ALWAYS add the acid to the water NEVER the other way round or you could end up with serious acid burns.
 
TradewindSailor said:
Phosphoric acid works .... but at stronger dilutions than coke:-)

Muriatic Acid (Hydrochloric Acid) is much cheaper but also more aggressive to the bronze. I use a 5 part water to one part HCl .... but I don't know the concentration of the HCl in the bottle. Keep an eye on it and don't leave it in the solution longer than necessary to soften the fouling. ALWAYS add the acid to the water NEVER the other way round or you could end up with serious acid burns.
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Concentrated hydrochloric acid as in laboratory chemicals is usually about 36% and anything over about 20% is likely to fume. You can but read the label or check the suppliers literature to determine the concentration of the product you are buying.

The advice regarding adding acid to water is very relevant to diluting concentrated sulphuric acid. It is sensible practice with other concentrated acids but they do not present quite the same dangers as sulphuric acid.
Adding water to 36%HCl produces lots of HCl fumes but the lower the concentration you start with the less problem you will have.
 
Hydrochloric acid does not attack either brass or bronze, so is safe on virtually any prop or skin fitting. Unless buying from a specialist you will be unable to buy in greater strengths than about 20% but as brick cleaner probably less than that.

I posted a photo a couple of days ago showing hydrochloric acid removing carbonate salts from a VHF aerial bracket. The bracket is aluminium, the fitting is stainless steel. All the salts were removed and neither metals was attacked. Hydrochloric acid is generally less agressive than sulphuric and nitric because it is not an oxidiser.
 
vyv_cox said:
I posted a photo a couple of days ago showing hydrochloric acid removing carbonate salts from a VHF aerial bracket. The bracket is aluminium, the fitting is stainless steel. All the salts were removed and neither metals was attacked.
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Would this work on helping remove stainless bolts/screws from aluminium fittings or is it a different form of corrosion in this case?
 
vyv_cox said:
Hydrochloric acid does not attack either brass or bronze, so is safe on virtually any prop or skin fitting. Unless buying from a specialist you will be unable to buy in greater strengths than about 20% but as brick cleaner probably less than that.

I posted a photo a couple of days ago showing hydrochloric acid removing carbonate salts from a VHF aerial bracket. The bracket is aluminium, the fitting is stainless steel. All the salts were removed and neither metals was attacked. Hydrochloric acid is generally less agressive than sulphuric and nitric because it is not an oxidiser.
Click to expand...

I've always found the HCl attacks aluminium rather aggressively ....
 
Here's the pic. The acid is 10%. You'll have to take my word for it that the aluminium was not attacked but I can take a photo to prove it.
IMG_0740_zps4d5a2e38.jpg
 
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