Hydrochloric acid effect on prop antifoul?

LittleSister

LittleSister

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Following on from recommendations on a recent thread, I was going to use dilute Hydrochloric (actually a Domestos gel product of 8.5%) to remove the fouling (remains of barnacles etc.) on a bronze prop

The prop currently has some remaining antifouling paint on parts of it (Trilux IIRC), as I had run out of time/patience/energy trying to get the paint and fouling off with wet and dry. Will the hydrochloric remove the paint? Or create some terrible hazard (worse/different from the fumes said to arise from the acid on the fouling itself)?

Any other advice/suggestions welcome.
 
LittleSister said:
Following on from recommendations on a recent thread, I was going to use dilute Hydrochloric (actually a Domestos gel product of 8.5%) to remove the fouling (remains of barnacles etc.) on a bronze prop

The prop currently has some remaining antifouling paint on parts of it (Trilux IIRC), as I had run out of time/patience/energy trying to get the paint and fouling off with wet and dry. Will the hydrochloric remove the paint? Or create some terrible hazard (worse/different from the fumes said to arise from the acid on the fouling itself)?

Any other advice/suggestions welcome.
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Goggles and gloves and a good water supply to wash away splashes and spillages.

I'd not think it will have much effect on the paint.. Get that off with some caustic soda perhaps, or paint stripper, if you want to get it off..........Full face shield, gloves and an plastic apron for using caustic soda
 
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VicS said:
Goggles and gloves and a good water supply to wash away splashes and spillages.

I'd not think it will have much effect on the paint.. Get that off with some caustic soda perhaps, or paint stripper, if you want to get it off..........Full face shield, gloves and an plastic apron for using caustic soda
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Many thanks, Vic. Just the sort of practical advice I needed. Much appreciated.
 
Be careful, it WILL attack the zinc in the prop. That's the problem with using any acidic product to attack the calcium fouling.
 
Topcat47 said:
Be careful, it WILL attack the zinc in the prop. That's the problem with using any acidic product to attack the calcium fouling.
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Nonsense. In the first place the OP says he has a bronze prop, which contains no zinc. Secondly, I tested and wrote up in YM a series of tests in which I exposed brass, bronze and DZR to a range of chemicals including HCl. None had the slightest effect. Thirdly, alloys are exactly that, not a mixture from which one element can be selectively leached.

Even if the alloy was susceptible to the acid it would take some considerable time to have any appreciable effect. Aluminium is supposedly attacked by HCl but I have used the acid several times to remove carbonate deposits without any noticeable attack of the aluminium.
 
May I drift my own thread? A while back I asked for suggestions for getting the old scale off of an anchor chain. Some suggested brick cleaner (IIRC) and the like, but others said that would be too strong and probably remove the galvanizing too, and a mild acid like vinegar was suggested. Would dilute (8.5%) hydrochloric be any good for that job?
 
Vinegar is an extremely weak organic acid that has minimal effect on cabonate scales. Hydrochloric acid in any strength is going to react with the zinc on your chain, that's how it is removed professionally before re-galvanising. Sulphamic and phosphoric acids have good reputations for cleaning out scales in engines but I think VicS may have to advise their effects on galvanising.
 
Phosphoric acid will attack the zinc. It's used in etching galvanized steel prior to powdercoating for example.
I'm not sure about sulphamic acid. Suphuric though will certainly attack zinc, similarly to HCl.
Getting it dilute doesn't really help in this case. Galvanizers use typically 1-3% HCl to strip old galvanizing off steel prior to re-galvanizing, as much stronger is too vigorous a reaction.

I've cleaned up chain by putting it in a concrete mixer with water and sand.
 
LittleSister said:
Following on from recommendations on a recent thread, I was going to use dilute Hydrochloric (actually a Domestos gel product of 8.5%) to remove the fouling (remains of barnacles etc.) on a bronze prop

The prop currently has some remaining antifouling paint on parts of it (Trilux IIRC), as I had run out of time/patience/energy trying to get the paint and fouling off with wet and dry. Will the hydrochloric remove the paint? Or create some terrible hazard (worse/different from the fumes said to arise from the acid on the fouling itself)?

Any other advice/suggestions welcome.
Click to expand...

Apologies if you've already checked this but are you sure the Domestos product you are using is based on hydrochloric acid? Domestos bleach is based on sodium hypochlorite, a very different beast material from hydrochloric acid. I don't think it would have much effect on barnacles etc but it might be better for removing the old paint than acid
 
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LittleSister said:
May I drift my own thread? A while back I asked for suggestions for getting the old scale off of an anchor chain. Some suggested brick cleaner (IIRC) and the like, but others said that would be too strong and probably remove the galvanizing too, and a mild acid like vinegar was suggested. Would dilute (8.5%) hydrochloric be any good for that job?
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vyv_cox said:
Vinegar is an extremely weak organic acid that has minimal effect on cabonate scales. Hydrochloric acid in any strength is going to react with the zinc on your chain, that's how it is removed professionally before re-galvanising. Sulphamic and phosphoric acids have good reputations for cleaning out scales in engines but I think VicS may have to advise their effects on galvanising.
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MM5AHO said:
Phosphoric acid will attack the zinc. It's used in etching galvanized steel prior to powdercoating for example.
I'm not sure about sulphamic acid. Suphuric though will certainly attack zinc, similarly to HCl.
Getting it dilute doesn't really help in this case. Galvanizers use typically 1-3% HCl to strip old galvanizing off steel prior to re-galvanizing, as much stronger is too vigorous a reaction.

I've cleaned up chain by putting it in a concrete mixer with water and sand.
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Firstly do not confuse strength and concentration. The term "strength" relates to the extent to which an acid is ionised , or dissociated, in aqueous solution.
The strong acids, hydrochloric, sulfuric and nitric to all intents and purposes dissociate completely. They will react vigorously with carbonates such as limescale or shell and with metals such as zinc, even when well diluted
The weak acids eg the organic acids, sulfamic acid and phosphoric acid only partially dissociate. They react relatively slowly with carbonates and metals.

Oxalic acid is the strongest of the common organic acids. Phosphoric acid is slightly weaker and sulfamic acid slightly stronger. Acetic acid is considerably weaker.
The concentrations of oxalic acid and sulfamic acid solutions is limited by their solubility. Likewise the concentration of hydrochloric acid is limited by the solubility of hydrogen chloride gas in water.

Although dilution will slow the rate of reaction of a strong acid it will also reduce the quantity of scale it can remove before becoming neutralised. The concentration of acetic acid in vinegar is about 5%. it will dissolve about the same quantity of scale as hydrochloric acid diluted to a concentration of approx 3% HCl but it will do so very much more slowly..
 
Pasarell said:
Apologies if you've already checked this but are you sure the Domestos product you are using is based on hydrochloric acid? Domestos bleach is based on sodium hypochlorite, a very different beast material from hydrochloric acid. I don't think it would have much effect on barnacles etc but it might be better for removing the old paint than acid
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One of these perhaps which contain hydrochloric acid and sulfamic acid

2089-994492-power-fresh-312x525.png
2089-994493-zero-limescale_312x525.png
 
We can buy over the counter 20% HCl as a concrete and toilet cleaner. It works a treat on my prop and other underwater metals. Spray with a hand atomizer, leave it for a bit, scrape, wash. Repeat several times. Coarse wet n dry. Straighten back, Grin.
 
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