It's Oxalic-time again!

Krusty

Krusty

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It\'s Oxalic-time again!

In recent years I've adopted Oxalic acid in solution, thickened with a little wallpaper paste, in preference to the costly stuff on chandlery shelves: thanks to advice on this forum.
I choose a dull damp day so that it has time to work its wonders before drying off, and have a hose rigged up and handy. Then work in panels; that is areas from toe-rail to waterlinw that I can cover without moving the step-ladder: paste panel 1; move; paste panel 2. Then into the repetitive sequence of paste panel 'n'; hose-off panel 'n-2'; move; paste 'n+1'...
I find that gives the stuff about three to four minutes to work, and it stays moist for at least that time, so it hoses off OK.
Once set up, I get round the hull in about an hour. Today I broke the sequence to take pictures before-and-after its 3-4 minutes work on waterline staining.

Oxalic01.jpg


Oxalic03.jpg


On reflection, it was well worth the time and small effort.
 
Re: It\'s Oxalic-time again!

am well impressed, bet its cheaper than the bottle of starbrite for £11 i bought the other week, can you go into detail about where you get the stuff from and what the ratios are?
Stu
 
Re: It\'s Oxalic-time again!

Just one point re oxalic acid and Y10..It appears to rip all the existing polish off as well! I did pretty much what you have done ie the entire hull and was amazed at the improvment, however having observed just how quick it attracted dirt again, I now only ever clean up the water line and always polish afterwards !

Regards Nick
 
Re: It\'s Oxalic-time again!

I don't like to worry you but.......
















someone' has nicked your mast and boom...

/forums/images/graemlins/laugh.gif
 
Re: It\'s Oxalic-time again!

I bought 1kg Oxalic Acid crystals from agwoodcare.co.uk: (Google for address)
and have used it at about 20% w/w solution; adding enough wallpaper paste (by trial and error) to make it creamy; in an old ice-cream tub; applied with a car-sponge. Wearing rubber gloves of course; it is poisonous!
I think I paid about £20, including delivery, and at this rate it is going to last me at least five years, perhaps nearer ten.
 
Re: It\'s Oxalic-time again!

I agree it does seem to take the shine off, but I don't think it actually strips off the polish; just matts the surface, perhaps, because I find the re-polish is easier than 'last time'. I have been using 'Mer'. The finish is not likely to come up 'as new' after 35 years and close to 100K sea-miles, but it is not bad; at a distance!

Piotapontoon2.jpg
 
Re: It\'s Oxalic-time again!

I am no chemist. The bits on my boat that need staining cleaning off are around the anchor locker and foredeck: what does the acid do to aluminium toerails and cleats and S/S fittings ?
 
Re: It\'s Oxalic-time again!

Nothing damaging, (as far as I can recall, but my chemistry is becoming rusty). I hope a more recently-practising chemist will come in and confirm that for you.
Oxalic does not shift rust stains in minutes, if ever; they need something like citric acid (lemon juice) or phoshoric acid. But it does shift green algae from crevices, wood and treadmaster-type deck-coverings.
Good luck with your problem-solving!
 
Re: It\'s Oxalic-time again!

...what does the acid do to aluminium toerails and cleats and S/S fittings

No effects in my experience; we regularly (once every couple of weeks) oxalic acid the foredeck during the summer, it shifts the rust-stains without apparent damage to either our cleats or non-slip deck paint.
 
Re: It\'s Oxalic-time again!

[ QUOTE ]
what does the acid do to aluminium toerails and cleats and S/S fittings

[/ QUOTE ] I would have advised avoiding contact with aluminium although stainless steel should be OK but if others have found no problems then fair enough.

I am surprised that anyone has found it slow to remove rust stains. I would have expected it to be better than citric acid and certainly lemon juice. Phosphoric acid is a stronger acid so it is reasonable to expect that to be quicker.
 
Re: It\'s Oxalic-time again!

In Malaysia we use "Mosaic Tile Cleaner". Available from most stores and "supermarkets" It rips the rust from stainless in no time as well as cleaning rust marks off GRP. It is obviously an acid but no markings on the container. Cheap at about 2 UK Pounds/Ltr.
 
Re: It\'s Oxalic-time again!

Great post, Piota. Dramatic photo too.

[ QUOTE ]
and what the ratios are?

[/ QUOTE ]
Shake up a lot of crystals with warm water to get a concentrated solution (keep adding crystals till there are some undissolved ones at the bottom). Then pour off the solution from the top into a suitable working container - bowl or whatever. Add sufficient paste to only slightly thicken (too much and it dries quickly and is more difficult to wash off).

I keep the 'solution' bottle permanently filled . . . no paste is needed for rust stains around stanchion feet, so then that's just a quick wipe and wash job.

Mister health and safety will jump down my throat for saying this, but many people consume oxalic acid regularly - in very small amounts - through rhubarb stalks. The leaves have much bigger concentrations - around 0.5% - which makes them distinctly poisonous.
 
Re: It\'s Oxalic-time again!

[ QUOTE ]
You can buy it at your local chemist

[/ QUOTE ] You might be able to but other folk have found that some pharmacies will order and sell it while others won't.
 
Re: It\'s Oxalic-time again!

Great picture ! I have given up the battle to try and make my 1971 built hull shine ! Actually she was sprayed about 18 years ago ( don't know why but I have the invoice)...so all the old paint is coming off and new 2 pack going on. Also whilst she is out and being 'dried' I am having the bottom blasted and a couple of coats of 'poxy gel seal applied.

Regards Nick
 
Re: It\'s Oxalic-time again!

Thanks for the comments and more practical tips. I shall adopt the idea of a bottle of saturated solution in the 'bosun's box'.
Also glad to know that I was wrong about its effect on rust-stains: thanks to VicS. I've been fortunate in not having to deal with any significant ones.
As usual, this forum comes up trumps!
 
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