Which Oxalic Acid to buy

[Hoist]

I'm interested in trying Oxalic acid to clean and whiten the decks of our Moody 336.

I keep on top of it every year with the jetwash and polish the shiny parts however it is a bit creamy now or dull rather than white

I've seen time and time again this oxalic acid stuff being mentioned but never used it or know which is best to buy

I did try some crystallized stuff labelled as gelcoat stain remover from the chandlers but I didnt see any difference in the stain I was trying to remove!

The chandlers warned me it was super strong but honestly I saw it do nothing so I doubt it was oxalic acid. In the end I used fairy washing powder to do the job!

Just would love to hear experiences and products used.

Ready mixed or do it yourself etc etc

Happy Sunday!

( just found the one I tried Riptide Wipe Clean GRP Cleaning Powder - Polymarine RIB Inflatable boat repair (polymarineshop.com) )

 

[Graham376]

I usually buy off ebay, powder dissolves better in hot water than crystals. In use, needs warmish weather and usually removes yellow hull waterline stain in about 20 minutes. Can be thickened with wallpaper paste but for a deck, just paint on or use a rose sprayer or similar.

 

[Jamie Dundee]

Oxalic acid removes staining, waterline, rust etc but doesn’t actually clean a dirty/faded surface.

 

[pvb]

I'd try something like dishwasher gel on a deck.

 

[Daverw]

This is what we buy

Oxalic Acid 1kg Tub Boat Cleaner and Rust Remover Pure Chem (White) | eBay

 

[Ian_Rob]

This is what we buy

Oxalic Acid 1kg Tub Boat Cleaner and Rust Remover Pure Chem (White) | eBay

That what I bought a quite a few years back. According to the label it is well past its expiry date but it continue to be very effective.

 

[Hoist]

does it whiten the deck also in your experience?

cheers for the replys everybody!

 

[Ian_Rob]

My experience is that it certainly whitens the decks. I mix as a 12% solution and add wall paper paste and assuming it is reasonably warm, you can see most yellowing disappear within 10 mins or so. It is remarkably effective.

 

[Stemar]

According to the label it is well past its expiry date

Unless it gets damp and sets into a lump, it's hardly going to go off. I had some I had in a jar for 10 years or more, but I foolishly left it on Jissel when I sold her. I'd been half looking for some more, but had only seen the stuff sold for bee-keepers' at silly money, so I've just ordered one of those tubs, which should see me out.

 

[Appledore]

The last batch I bought off Fleabay did not seem to have the same strength as purchases from a few years ago. Like most chemicals, they seem to be less effective than they used to be.

 

[Refueler]

I bought powder version .. 1kg of eBay .....

Mix : - The recc'd 100gr to 1 ltr hot water did nothing .... so I upped to 200gr + Wallpaper paste ... that then did the trick.

But it does need something after washing off the Oxalic ... a non silicon wax. if its hull ... but deck ? Reckon just leave that as is after.

 

[Ian_Rob]

When you consider the price of the proprietary gel that you can buy and that you mix up your own with an £0.80 bag of wallpaper paste and achieve exactlly the same if not better results, there is no contest. I have seen it mentioned that you can add food colouring to help you see where you have applied it. I never done this but it seems a good idea.

 

[Refueler]

The last batch I bought off Fleabay did not seem to have the same strength as purchases from a few years ago. Like most chemicals, they seem to be less effective than they used to be.

I found same - I had to double the ratio to water ....

My previous cure for hull staining was Cilit Bang Lime and Rust Remover ..... but last few years - its been absolute rubbish.

 

[jwilson]

In present 20 C temperatures oxalic acid crystals mixed with hot water to a saturation solution (till no more crystals dissolve), gets brown waterline stains off in 2-3 minutes. Rust stains on deck from rusty mooring chains take slightly longer, but not much. Then i wash off as soon as possible: I'm not convinced it's good for other metalwork.

Some GRP hulls and decks seem to suffer worse from brown staining than others. Whatever I do with polish over winter does not seem to stop my hull getting a brownish around-waterline stain. After 2-3 months afloat it looks horrible, and oxalic acid sprayed on warm and then hosed off fixes it, though it may well strip the polish off locally.

 

[pvb]

When you consider the price of the proprietary gel that you can buy and that you mix up your own with an £0.80 bag of wallpaper paste and achieve exactlly the same if not better results, there is no contest. I have seen it mentioned that you can add food colouring to help you see where you have applied it. I never done this but it seems a good idea.

I suppose it depends on how much of the stuff you need to use, which probably depends on where you use the boat. I find that a tub of Y-10 or similar is very convenient to use and lasts me years.

 

[Ian_Rob]

In present 20 C temperatures oxalic acid crystals mixed with hot water to a saturation solution (till no more crystals dissolve), gets brown waterline stains off in 2-3 minutes. Rust stains on deck from rusty mooring chains take slightly longer, but not much. Then i wash off as soon as possible: I'm not convinced it's good for other metalwork.

Some GRP hulls and decks seem to suffer worse from brown staining than others. Whatever I do with polish over winter does not seem to stop my hull getting a brownish around-waterline stain. After 2-3 months afloat it looks horrible, and oxalic acid sprayed on warm and then hosed off fixes it, though it may well strip the polish off locally.

I believe I am right in saying that it should be kept away from aluminium……?

 

[Ian_Rob]

I suppose it depends on how much of the stuff you need to use, which probably depends on where you use the boat. I find that a tub of Y-10 or similar is very convenient to use and lasts me years.

I reckon I use the equivalent of two 320g tubs of Y10 each season to clean my hull at and about the waterline, at the stern and around the exhaust outlet.

 

[pvb]

I reckon I use the equivalent of two 320g tubs of Y10 each season to clean my hull at and about the waterline, at the stern and around the exhaust outlet.

As I said, it depends on boat location. It probably also depends on what protection you put on the hull after using oxalic. I do two coats of polish, followed by two coats of wax.

 

[Daverw]

Being in the east coast mud we have to wash off mud stain each month, nothing else moves it as easily as oxalic acid, quite weak solution needed, spray on with garden sprayer, wait 10 minutes and brush off with soft brush and we are white again

 

[Refueler]

Being in the east coast mud we have to wash off mud stain each month, nothing else moves it as easily as oxalic acid, quite weak solution needed, spray on with garden sprayer, wait 10 minutes and brush off with soft brush and we are white again

That's fine when you do it regularly before the mud actually stains .... but I bet if you didn't do that - if left for a season - then that weak solution may have a less effect.