Oxalic acid again

[Mr Cassandra]

I got some Oxalic acid from the chemist 1 kg £10 asked him what sort of ratio to mix it with he did not know . He was very inpresed when I explaind what I was going to use it on [ Cleaning Gell coat ]Mixing it with wallpaper paste, so that it would stick to the vertical sides of the boat . I have read all /most of the posts on the forum but still need the answer what ratio to mix it to for best results .
Thanks bob t

Bob T

 

[steve_cronin]

Re: Oxalic acid

Mix it up until you get a concentrated solution (school chemistry) . This will take about four tablespoons in a jam jar as I remember.

This is a much cheaper way of de-rusting than Y10 but as you say it is thin and has no holding power. I personally wouldn't use wallpaper paste as the gelling agent as this can dry like concrete if left in awkward places for too long. Try cheap hair gel instead. You can get it in tinted varieties and it is always water soluble.

Don't forget that you need >60F for the oxalic (phosphoric) acid to work at all. On a hot summers day it seems to work instantly. It is also superb for brightening stainless steel and keeping bottle screws free & looking smart.

Steve Cronin

 

[Mr Cassandra]

Re: Oxalic acid

I got expelled from chemistryWhen we attemted to make exposives ,can still remember the BANG, even now. Was also chucked out of English [ Better get that in before the crowd voice it] I am going to Greece 2nd week in feb it is 17deg at the moment there. I supose i could mix it with warm water? and use the tinted hair gell to hide the grey Thanks bob t

Bob T

 

[ianwright]

One pound of oxalic acid to a gallon of boiling water (2oz to a pint) will give you a saturated solution.
The teak cleaners you might buy in your chandlery use a 10%-16% solution so you might like to start weak and see.
A strong solution will mark paint and gelcoat so rinse the hell out of it.

IanW

Vertue 203, Patience

 

[steve_cronin]

Never marked when I used it...

But caution, like patience, is a Vertue!!

 

[Geoffs]

Thing to remember, as has been pointed out before, Oxalic Acid is highly toxic. So when mixing it's rubber gloves safety goggles etc. If it gets on skin wash off quickly, if any ingested, medical help double quick. Any clothing worn during the process, wash soon after.

 

[Miker]

So that was what burnt holes in my jeans.

I spilt a proprietory cleaner containing oxalic acid when cleaning the boat. I must apologise to my wife for blaming her laundry services.

 

[ianwright]

Try leaving an oxalic dribble down your topsides ,

,,,,,, and letting it dry in the sun. Ouch!

IanW
Patience Vertue 203

Vertue 203, Patience

 

[vyv_cox]

Toxic Oxalic acid

Concentrated oxalic acid can burn the skin and for this reason a weaker mix is safer, about 15% will do little damage to anyone. Keep it in perspective though, this is not fuming nitric, it's about as dangerous as domestic bleach. It is quite poisonous, about 25 grams needed to kill, but again bear in mind that most vegetables contain oxalic acid, especially rhubarb leaves. Apparently you need to eat about 5 kg to kill you - probably not many takers for this particular form of suicide.

I use TeakBrite for my source of oxalic. I've had the same pot for years now. It acts very quickly, so I have never found the need to thicken it with anything. I just dip a wet brush in a small tray of the powder, rub it on decks and topsides and within seconds it removes all traces of yellowing. Sometimes a little encouragement with the brush is needed. Trouble with using it is that everything else then looks old and tired and the whole boat needs doing.

I recently "found" Black Streak Remover. This is EDTA solution, not poisonous at all. Fantastic stuff, even better than oxalic acid. I have sometimes suspected that oxalic roughens the surface of GRP, allowing yellowing to occur more quickly the next time. EDTA does not do this.

 

[steve_cronin]

Re: Try leaving an oxalic dribble down your topsides ,

Yes it dries but apart from the cleaning effect it has no chemical effect on the gelcoat.

 

[steve_cronin]

Re: Try leaving an oxalic dribble down your topsides ,

Yes it dries but apart from the cleaning effect it has no chemical effect on the gelcoat. However, if your Vertue is painted??

 

[steve_cronin]

Oh yes....

it will remove any vegetable material & cotton will do nicely.

It is very effective (much more so than hypochlorite bleach) on patio tiles & paving slabs. It is usedd also to clean wooden garden furniture.

 

[longjohnsilver]

EDTA?

What does this mean?

 

[Guest]

effect on painted gelcoat

I intend to use this stuff for the deck, if it drips on to the painted topsides and i don't notice it, will it do ant damage to my paint work?

 

[ianwright]

Re: effect on painted gelcoat

Yes, but slight.

Vertue 203, Patience

 

[vyv_cox]

Re: EDTA?

You asked for it. It stands for ethylenediaminetetraacetic acid, used as a sequestrant food additive to remove unwanted metal ions that would otherwise cause the food to go off. It is also used in medicine, somewhat controversially it seems. However, these two examples indicate it to be perfectly safe, and it is the best topsides cleaner I ever found.

 

[Nikolai]

We also don't use oxalic acid for this purpose here in Russia. The idea about EDTA seems to be good, and it is simplier to buy, too

Nikolai, Moscow

 

[Rosa]

Re: EDTA?

Vyv-having told us what EDTA is, I'm still in the dark-What do you do with it? From what you say it sounds good stuff, but I'd like to know about solution strength, time, rinsing, safety etc. Thanks.

 

[vyv_cox]

Re: EDTA?

It's sold as Black Streak Remover in chandlers. If you have a source of supply elsewhere, e.g. chemicals suppliers, no doubt this would be much cheaper. From memory, and a very long time ago, we used to make up fairly weak solutions, ~ 10%. No safety issues, it's an approved food additive.

 

[Rosa]

Re: EDTA?

Thanks for the information, Vyv. Will try it.