Oxalic acid / Muric acid.....

Sy-Revolution

Sy-Revolution

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Hi Folks,
Springs coming so it's clean-up time. Here in Portugal, in the local supermarket I found some Acido Muriatico, so I bought some hoping that it might be Oxalic acid. Well it seems similar, has cleaned up my top sides nicely plus got rid of rust stains on the stainless and brightened up the teak.

Googling I see that it is in fact Muric acid not Oxalic (yes perhaps i should have done that before using it!). So is it similar and more importantly is it safe to use as a boat cleaner as oxalic acid is?

Any ideas?

Cheers,

Cx
 
I've never come across muric acid, but muriatic acid is an old name for hydrochloric acid, which is possibly a bit fierce for the sort of use you describe (depending on concentration).
 
Yep muriatic acid is hydrochloric acid. A strong acid which I personally would not use for general cleaning. Keep off metal components if you do. Under controlled conditions or where no damage could be done it is very effective for de-scaling.
It is a solution in water of hydrogen chloride. Max concentration IIRC is around 36%. It is very corrosive.

Oxalic acid is a weak acid supplied as a white/colourless crystalline solid. It is only moderately soluble in water it is also somewhat toxic. Difficult to find solubility figures but probably about 12% (as the anhydrous form) at 20C

Oxalic acid is the active constituent of Y10 gel and is very effective for removing rust stains and the brown stain around the water line. It has gained the reputation as an effective GRP cleaner.
Also advisable to keep off metal fittings.

Oxalic acid is also used as for lightening wood work and can be effective in removing stains due to water.
 
Sy-Revolution said:
Ok gotcha, will be relegated to bog duties. Did a great job of my topsides though (concentation 12%)
Click to expand...

As well as a cupful in the bog every now and then, I used it to good effect in a spray bottle to get the barnacles off my propellor. Nothing else would touch them. Wear Gloves, it's very painful on the skin, particularly if it gets into tiny cuts or scrapes - how do I know :(
 
Oxalic Acid

In Italy they sell something that the local hardware store call "Acido di Muratore" which is white crystals and which is used for cleaning marble/tiled floors e.t.c.
The word Muratore is the term for a builder/bricklayer, deriving from Muro = wall.

Now, I have always used this as Oxalic acid which one of the hardware stores assured me it was (but I do not necessarily trust them). I have never had any problems and I use it about 10% -15% solution (one handfull in a 5 litre bucket) with my bare hands (don't tell H&S) and I've never had any problems either with hands or boat!!! and it cleans the gelcoat up a treat.

I am wondering if what you found in the supermarket is really Muric acid and not the Portuguese equivalent of Oxalic acid????

Alan.
 
Phosphoric acid also works well as a general cleaner on all sorts of things on a boat and at home. Widely available as - Cillit or even diet Coke!

It may not do all the things oxalic acid does, but it's great for cleaning up stainless, and all sorts of other kitchen / bathroom cleaning. Similarly kind on the base materials as oxalic, yet effective at getting contaminants and stains off.

That's certainly been my experience, don't know what VicS's thoughts are?
 
The Portuguese for 'hydrochloric' is clorídrico, but that's not to say it's always sold under that name. After all, in the UK it's often sold as 'spirit of salts'.

Oxalic is a much gentler acid than hydrochloric, but very effecive for gel cleaning, stainless rust removal, etc. It's found in, for instance, rhubarb, so an old engine-cleaning trick was to boil parts in a pan with a few rhubarb sticks. Like Vic, I'd caution against using anything stronger (than oxalic, not rhubarb).

Can't help with Portuguese common name for oxalic, but if it helps the formula is C2O2(OH)2 . The '2s' of course, should be in sub-script.
 
I believe HCl solution is sometimes sold as "Brick Cleaner", so very possible that that Italian product is some of the same!

Tho just spotted it was in crystalline form, so possibly not!
 
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On the bottle it's called:

Acido Muriatico
Acido Cloridrido 25%
Click to expand...

25% hydrochloric acid then .

I would have diluted it more than 50:50. Probably 1 part in 5 parts water if I used it at all for this purpose.
 
The Portuguese word is oxálico but the girl behind the counter in the drogaria in Olhão didn't know it - but she eficiently produced a proprietary brand when I asked for "tratamento para ferrugem " (rust).As has been said muriatico is fierce.
Jim
 
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