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Ratio for mixing oxalic acid and water


#1

Just a quick and easy question. What is the correct ratio for mixing
oxalic acid and water? I want to clean some rough by soaking it in
this solution but I don’t recall what the ratios were. I have the
oxalic acid in the powder form but no mixing instructions.

Thanks for your help in advance.

Rick Stutt
Wire Wrapping Etc.


#2

G’day Rick and y’all; be very careful with oxalic acid; it is very
poisonous. It combines with part of the blood haemoglobin and a
victim virtually suffocates from lack of oxygen. Use rubber gloves
and then wash your hands thoroughly - just in case. The concentration
for what you want to do is quite unimportant; a dessertspoon full in
the equivalent of a cup of warm water is sufficient. I suggest you
might prefer to use citric acid or sparex to do the job.

Cheers
John Burgess; @John_Burgess2 of Mapua Nelson NZ


#3

Wow John ! Oxalic acid is an old standby here in the “States” It has
been a standby in rock shops for the removal of ferrous stains from
rough rock and has never been associated with hazardous materials
considerations except to the extent that it is highly acidic and
should be treated as such. The conventional approach to its use has
been that it is best used when slightly heated and used in an
aluminum container. The net effect is that the ferrous contaminant is
precipitated on the aluminum container. I am alarmed by your
assertions that it is highly poisonous…it has been used
extensively by persons in the rock and gem hobbies and businesses for
many years and there have been no suggestions that it is hazardous.

I have been using oxalic acid for decades and have never used a
precise acid to water ratio. I simply mix a warm water / oxalic
combination and wait about twenty-four hours and examine the results.
If the results are efffective or promising, I proceed accordingly.Ron
at Mills Gem, Los Osos,CA.


#4
    Wow John ! Oxalic acid is an old standby here in the "States"
...It has been a standby in rock shops for the removal of ferrous
stains from rough rock... 

G’day; Whilst Oxalic acid is indeed poisonous, there is no need to
be over worried about it’s use; just treat it with all reasonable
care. And it is no more powerful an acid than Sparex.

As I suggested in my post, the reason it is poisonous is for the same
reason it is good at removing iron stains; it has an affinity for
iron and doesn’t really care where the iron comes from. So it mops
up the iron from blood haemoglobin and puts it in a sort of molecular
cage from which it can’t escape very easily. This ‘chelation’ causes
it to lose it’s colour too.

Perhaps I might mention here that in the old days (when I was a boy,
in fact!) ink was made with iron, and a solution of oxalic acid was
the housewife’s cure for ink stains on boy’s clothing. And fingers!
It was often referred to as ‘iron mould’. After such a use the cloth
and/or fingers would be washed in dilute washing soda, then
thoroughly rinsed under the tap.

Oxalic acid also exists in rhubarb leaves, hence all the old cook
books bore an admonition not to cook or eat the leaves, though the
stems were perfectly safe. The plant/weed ‘oxalis’ also contains the
substance - which is why you never see bugs and caterpillars eating
the leaves.

    I  have been using oxalic acid for decades and have never used
a precise acid to water ratio. I simply mix a warm water / oxalic
combination and wait about twenty-four hours and examine the
results. If the results are efffective or promising, I proceed
accordingly 

That’s fair enough; in many such applications of chemicals the
required strength is %$& “enough!” –

John Burgess; @John_Burgess2 of Mapua Nelson NZ


#5

It would be very wise to listen to John advice.I’ve got an English
dictionary because I like to improve my language and even the
dictionary is pointing on the very poisiouness fact of oxalic acid.I
never used this “hot” stuff and I think I never will.

Regards Pedro
Palonso@t-online.de


#6

Oxalic acid also exists in rhubarb leaves, hence all the old cook
books bore an admonition not to cook or eat the leaves, though the
stems were perfectly safe. The plant/weed ‘oxalis’ also contains the
substance - which is why you never see bugs and caterpillars eating
the leaves.

Some books say that 5 pounds of rhubarb stems are enough for serious
problems :frowning: Isn’t the oxalis plant sorrel or dock in plain English? I
should like to post a caveat from my experience - I have established
beyond doubt that oxalic acid (as in sorrel or rhubarb) causes
allergic rash on my poor body, so I have to avoid eating these
delicacies. If used just for removing iron, there should be no
problems, if some carbonates are present in/on the specimen
(limestone, marble and like), the “fizz” will take certain amount of
acid in the air, so people with possible allergies (and even without)
should avoid being close to this brew. Eddie, the chemist from Latvia