How to use oxalic acid?

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prv

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In the past I've not really bothered much with cleaning the outside of KS, beyond a hose and very occasionally a bit of washing up liquid. But she's looking particularly grubby right now so I think a bit more deliberate effort on the deck might be called for.

It's fibreglass with non-slip pattern, so I hear oxalic acid is the stuff to remove stains and general grime. I can see packs of it as powder on eBay for a few quid, and I assume I can just mix it with water in a bucket, slosh it on the decks, agitate a bit with the brush, then sluice it off.

But - what sort of proportions should it be mixed in for this kind of job?

With that mix - how nasty is it? (sandals / boots / long trousers and sleeves / spacesuit ?)

Likely to harm any other materials normally found on deck? How about varnished timber, which I have a fair bit of?

I did a quick search of the forums for the mixing proportions without finding anything - so all advice welcome.

Pete
 
Saturated, or nearly saturated, warm water will speed up the dissolution. use non metallic vessels

Can be thickened with wallpaper paste for use on vertical surfaces.

Keep it off deck fittings.

Remember it's toxic, its corrosive, its harmful by skin absortion and splashes will burn exposed skin if not washed off promptly.

Gloves and goggles are the absolute minimum protection required.

Read the safety data supplied or published by the supplier!

Dispose of waste safely . Properly label any you keep
 
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VicS has covered it. Only thing I might add is low temp. related. Vic said that warm water would speed things up (you can practically see stains go at 20 deg. C).

But don't bother using it on a cold day with cold water. I seem to remember the reaction pretty much stops below 10 deg. C. So it doesn't appear to do anything much at all. I remember giving someone some from the lab. years ago. He came back and said that it was useless (he'd tried it out on a cold day). Much happier when I mentioned the low temp. issue.
 
Cheers - I was imagining it as something closer to vinegar :) (I would of course have read the datasheet after buying any). Dissolves deck fittings, does it? I might have to revise my "slosh it about" plan.

Thanks,

Pete
 
prv said:
Cheers - I was imagining it as something closer to vinegar :) (I would of course have read the datasheet after buying any). Dissolves deck fittings, does it? I might have to revise my "slosh it about" plan.

Thanks,

Pete
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No does not dissolve deck fittings but could mark them.

However it's definitely not a "slosh about" sort of stuff.

An horrific tale on here very recently from someone who let it run up his arms

http://www.ybw.com/forums/showpost.php?p=3446187&postcount=3

It's a lot stronger acid than acetic acid and saturated is much more concentrated than the acetic acid in vinegar.
 
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I used some with washing up liquid on the yellow staining on the bows to try it out. Amazing stuff.
The problem is now the bow is back to white and the rest of the hull looks dirty.
 
prv said:
Cheers - I was imagining it as something closer to vinegar :) (I would of course have read the datasheet after buying any). Dissolves deck fittings, does it? I might have to revise my "slosh it about" plan.

Thanks,

Pete
Click to expand...

It won't dissolve your deck fittings THAT quick. I have gone off the idea of wall paper past, partly because it is one more thing to remove. If you add some detergent and get the mix to "foam" that can help it stick to the topsides for long enough to act.

Temperature: In practical terms it work well last week-end on Tigger. OK it was mild-ish, but not hot. (Cornwall, 18 March)
 
If you want to see what it can be used on etc. Have a look for BKF (Bar Keepers Friend) in your local supermarket. It is oxalic acid. It's what I use, one pot cleans all my topsides (Sigma 362). I have not taken any great precautions in use, but having read them on here, I may rethink that!
 
TiggerToo said:
If you add some detergent and get the mix to "foam" that can help it stick to the topsides for long enough to act.
Click to expand...

Ta, but I'm not applying it to the topsides. They're painted with basic one-pot black, so a) the acid might take it off b) they don't show the dirt so there's no need for it anyway. It's the white decks that have accumulated a layer of grime from being moored next to a scrapyard.

Pete
 
prv said:
Ta, but I'm not applying it to the topsides. They're painted with basic one-pot black, so a) the acid might take it off b) they don't show the dirt so there's no need for it anyway. It's the white decks that have accumulated a layer of grime from being moored next to a scrapyard.

Pete
Click to expand...

Fine, but adding a strong detergent (foamed up) to the oxalic acid mix will help to maintain a larger volume of water acting for a little while, as well as disperse oily residues.
 
i used half a 1kg bag in a gallon/4l of hot water with a squirt of fairy. worked ok. wear waterproof clothes wellies and marrigolds. and have a hose for washing off after about 10min of scrubbing with broom. not sure but i think thats about a 12% solution.
 
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The oxalic acid I bought from Ebay (500g) had instructions for boat cleaning - "Dissolve 150g in 1 litre of warm water and spray on" - DO NOT DO THIS! - unless it's a totally still day, it's impossible to avoid some of the spray blowback, and it's a nasty irritant - especially, don't breathe it in!

I've had best - and safer - results by mixing a similar quantity into a litre tub of Aldi gel handcleaner. Sticks well to vertical surfaces, and helps to penetrate any grease. Rub on with a nylon scouring sponge, leave for half an hour, then pressure wash. Wear gloves, and don't get any of the gunk in your eyes. Do the whole hull or you'll get a patchy result.

This mix will shift waterline brown stains a treat, but some other marks need a cutting agent - any cream cleaner suitable for baths works fine. Then after thorough washing, apply a good wax polish - I use Mer. Job done.
 
I mix mine with Fairy liquid. This has three advantages:
1. Makes it foamy, which means it doesn't dry out so fast when used on cooler days.
2. Allows me to see what area I've done, and the slight gree tinge helps too.
3. The detergent cleans other muck off that the acid doesn't.

So my recipe:
For a 250 ml container:
2 tablespoons of crystals (but don't use a metal spoon, it will etch it, use plastic)
Warm water to dissolve, about 100 ml warm.
A good healthy squirt of detergent, about 100ml.
Top up with cold water to make 250ml.

Use a scrubbing brush (plastic) to get the suds working, even on smooth surfaces.
Wait a while (temp dependent, 20 mins in Scotland!)
hose off.
 
One more thing I may add is to wet the whole hull first. That way you will not get what they call" super clean" streaks. That is run marks where it has cleaned just the parts where it has run down.
It is also used to brighten bare timber, decks, hand rails etc.
I have used it on prawn trawlers to remove grime etc. I have never had a problem with the acidity. Just wash yourself well after you finish. Glasses for eye protection are a nobrainer though.
 
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