oxalic acid as grp cleaner - what dilution please

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Furoner

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Having followed the oxalic acid thread am now ready to lift out boat and wipe its bottom- will our chemist friends pls advise strength (or otherwise) of dilution with water for sponging on and with a hand sprayer. Have read the safety leaflet and will comply....seems nasty stuff.
 
I mix around 2 table spoons in a medium coffee jar size - with warm water - seems to work fine..
See if you can get some borax for neautralsing - or copius amounts of water -wear eye protection and gloves if working upwards - advisable anytime though. 3 tablespoons in the same water container (Jar) works well for teak - never needed anything stronger.

Joe
 
AG Woodcare suggest 2 - 4 tablespoons in 1 pint of hot water (For wood bleaching)

You might as well make it more concentrated rather than less, even saturated many suggest.

You can thicken it with wallpaper paste so that it clings rather than simply running off onto the ground.

Ammonia or borax is the recommended solution for neutralising it an wood and stopping the bleaching action but on grp or spills just use washing soda or bicarb or just wash away with water. Bicarb or just water on you.

Take care but it is not as nasty as many things I could name. I remember the days when we pipetted a near saturated solution routinley by mouth!
 
[ QUOTE ]
seems a strange use for oxalyc ?

[/ QUOTE ] It puzzles me too but oxalic acid seems to have gain the reputation as the magic cleaner for everything. The perfect solution for iron (rust) stains and the brown stain around the waterline, not forgetting its traditional use for wood bleaching, but every thing else ????????
 
Thanks chaps; all seems clear. Didn't want to mix it too strong without knowing consequences. Tks for info re bicarb, didn't know that and can get it easily. Not using it under the boat but intend to clean waterline and hull prior new antifoul.
 
VicS said:
AG Woodcare suggest 2 - 4 tablespoons in 1 pint of hot water (For wood bleaching)

You might as well make it more concentrated rather than less, even saturated many suggest.

You can thicken it with wallpaper paste so that it clings rather than simply running off onto the ground.

Ammonia or borax is the recommended solution for neutralising it an wood and stopping the bleaching action but on grp or spills just use washing soda or bicarb or just wash away with water. Bicarb or just water on you.

Take care but it is not as nasty as many things I could name. I remember the days when we pipetted a near saturated solution routinley by mouth!
Click to expand...

Hi Vic,

To ensure I've understood correctly...

Normally, I just use copius amounts of water and gentle soft bruishing accross the grain on my teak decks. They are now a beautiful grey colour - to match my hair!

But the decks are suffering more nd more from green (suspect algea?) and black (suggest mould?). If I use Oxalic acid to clear this, will there be any damage to the teak at all?

I like the idea of using wall paper paste - excellent idea. But after washing it all off, I then use ammonia or borax to neutralise the acid left in the teak?

I see, for example that Boots sell ammonia in a 9.5% solution. Is this the correct concentration to wash over the decks?

And there's no damage to GRP?

My chemist days are long gone. I liked it at O level, but the A level teacher just lost me, and my love for Chemistry waned. Sad. Hence the above questions.
 
If you use oxalic acid to restore the colour to wood then yes to stop the action rinse with dilute ammonia. SEE http://www.agwoodcare.co.uk/more_info_oxalic.html

I notice AG Woodcare suggest borax as an alternative to ammonia. That might be a good choice in the circumstances but to prevent algae and mould I think what you need is a wood treatment such as Boracol 20 or a deck treatment from your DIY store.
 
Piers said:
Hi Vic,

I like the idea of using wall paper paste - excellent idea. But after washing it all off, I then use ammonia or borax to neutralise the acid left in the teak?
Click to expand...

I have never felt the need to thicken with wallpaper past.

Just use a damp sponge. Cannot see the need for it.
 
I tried the Harpic method, following suggestions on the forum, didn't work adequately for me. Oxalic has been fine, brown stain removed easily, sponge on and leave for ten minutes or up to an hour or more if needed. I often just leave it and forget it, leave it the rain to wash it off.

If your hands are sensitive, then was it off. I ignore it with no problems.
 
I would suggest using water to wash off the Oxalic acid rather than using an alkali to try and neutralise it. Many woods are slightly acidic naturally, so a little remaining acid is not going to do it any harm, however, overdo the alkali, and you risk damaging the structure of the wood. Lots of water is much safer.

Also, be careful about getting oxalic acid on anodised aluminium. It's scary how fast it can eat it.
 
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Woodlouse said:
Also, be careful about getting oxalic acid on anodised aluminium. It's scary how fast it can eat it.
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That's an interesting point, Woodlouse. I was going to have a go with Oxalic acid and envisaged leaving it on the deck for a while to do its job ( a few rusty stains there need seeing to). However, my boat has an aluminium toerail and various aluminium bits on deck. Sounds like I need to be careful! I'll still use it but will keep a close eye on the toerail.
Cheers,
 
Humblebee said:
That's an interesting point, Woodlouse. I was going to have a go with Oxalic acid and envisaged leaving it on the deck for a while to do its job ( a few rusty stains there need seeing to). However, my boat has an aluminium toerail and various aluminium bits on deck. Sounds like I need to be careful! I'll still use it but will keep a close eye on the toerail.
Cheers,
Click to expand...
I use it, slosh it all over, lewmar hatches, toe rail etc etc, no probs
Stu
 
Furoner said:
Having followed the oxalic acid thread am now ready to lift out boat and wipe its bottom- will our chemist friends pls advise strength (or otherwise) of dilution with water for sponging on and with a hand sprayer. Have read the safety leaflet and will comply....seems nasty stuff.
Click to expand...

Surely it depends on the dilution that it comes in to start with
One assumes that you will not be able to buy it in concentrated form
So if it is pre diluted then you would need to know by how much before you know how much more dilution you need
Or is that totally wrong?
 
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