Rust removal methods safe for cutting tools / precision parts?

[mark smith 20Participant @marksmith20]

**LINK**

[Tim StevensParticipant @timstevens64731]

An interesting error in the Patent which Mark Smith has found – and thanks for that, very helpful:

The much higher free acid present in the solutions according to the invention allows much of the ion to exist in a ferrous state.

I am certain that the word 'ion' should be 'iron'. There will be ions in the mix, for sure, but there ain't no such animal as an ion in a ferrous state, when you start with citric acid and ammonia, and therefore you include no iron at all until the rust removal starts. I think what they actually meant was 'iron ions … in a ferrous state'.

The intro does make it clear that the text has been prepared by OCR, so may include errors.

In conclusion, make up your ammoniated citric acid in concentrated form, and use it diluted. Once diluted it will go mouldy.

Regards, Tim

Edited By Tim Stevens on 03/12/2017 15:27:42

[maurice bennieParticipant @mauricebennie99556]

hi Martin Thanks for the reply , I was ,many years ago ,a technician in a pharmaceutical co, know a bit of chemistry

that was a nice lesson ,now understand what happens .

Maurice.

[Mark RandParticipant @markrand96270]

As I noted above, you do get ferrous citrate produced with steel and citric acid. It's almost insoluble, so you get a thick layer of precipitate. You wouldn't get that with the other posited reaction.

 

PS:- I see nothing novel in that patent application. I hope it was denied…

Edited By Mark Rand on 03/12/2017 21:01:40

[Martin DowingParticipant @martindowing58466]

@Fowlers Fury

Quote from your link regarding Copper citrate:

"H302 (100%): Harmful if swallowed [Warning Acute toxicity, oral]
H315 (11.43%): Causes skin irritation [Warning Skin corrosion/irritation]
H400 (77.14%): Very toxic to aquatic life [Warning Hazardous to the aquatic environment, acute hazard]
H410 (74.29%): Very toxic to aquatic life with long lasting effects [Warning Hazardous to the aquatic environment, long-term hazard]"

I cannot find here at all that it is causing serious eye damage and only 11.43% of reports (not 93.75% as you claim) are recording skin irritation.

My own impression about copper citrate is that it is relatively harmless compound, unless consumed deliberately in considerable quantities and will cause skin irritation and sometimes allergy in rather few particularly careless or sensitive individuals, though I would avoid breathing in dust of it.

Statements about toxicity to aquatic life are correct albeit I would call it "toxic", not "very toxic" because if it is "very toxic" then other common industrial chemicals like cyanides would be "very very very toxic". You could not call them "extremely toxic" either because if you do, then alcaloid pilocarpine would be "extremely extremely toxic" etc.

From my own long industrial experience as research chemist I have found that most of risks assesments are rather political/legal documents of very limited value in real life. Their production is a great time wasting exercise and it is sometimes actually endangering health of workers because they are first forced to produce this nonsense to satisfy legal requirements and then they still must complete planned tasks, often in hurry and therefore without proper attention, because much time already was wasted on writting risk assessments, getting them authorised etc.

Re: descaling of copper from copper oxide: I would use 10-20% hydrochloric acid but on copper, not on brass. You can remove copper oxide from copper or brass with disodium salt of EDTA (di-sodium ethylenediamiotetraacetate or di-sodium wersenate) at pH 7-8, eg essentially neutral conditions.

You can easily buy this reagent over Internet. It is used for lead battery reconditioning and many other things and rather cheap. It will not remove copper sulfide scale only copper oxide.

Martin

[Fowlers FuryParticipant @fowlersfury]

(1) "only 11.43% of reports (not 93.75% as you claim) are recording skin irritation."
I am not claiming that, it is reproduced from the literature.
(2) "R(risk) and S(safety) phrases are assigned to chemicals by concensus in an expert committee of the EU. The risk phrases are somewhat of a misnomer because they are hazard phrases but distinguishing between those 2 concepts is linguistically difficult elsewhere in Europe.You are of course free to make your personal assessment of risk with "My own impression about copper citrate is that it is relatively harmless compound".
(3) "From my own long industrial experience as research chemist I have found that most of risks assesments are rather political/legal documents of very limited value in real life".
From my long experience as a toxicologist in the chemical industry I have a different view.
(4) "Their [risk assessments] production is a great time wasting exercise and it is sometimes actually endangering health of workers because they are first forced to produce this nonsense to satisfy legal requirements"
As a past member of the HSE's Advisory Committee on Toxic Substances, I assure you the TUC, CBI and HSE members think otherwise.
(5) I also use dil HCl to remove Cu oxide.

[Martin DowingParticipant @martindowing58466]

@ Silly Old Duffer

Reaction of citric acid with rust is discussed here:

"Chemistry and metallurgy" Second Revised and Enlarged Edition; A. Sherry; J. S. Beck; A. E. Cruddace; page 357;

It reads:

"Fe2O3 + 2 H3Citrate —-> 2 FeCitrate + 3 H2O

where citric acid is represented by H3Citrate to simplyfy formula."

Martin

[Martin DowingParticipant @martindowing58466]

Posted by Fowlers Fury on 03/12/2017 22:32:41:

(1) "only 11.43% of reports (not 93.75% as you claim) are recording skin irritation."
I am not claiming that, it is reproduced from the literature.
(2) "R(risk) and S(safety) phrases are assigned to chemicals by concensus in an expert committee of the EU. The risk phrases are somewhat of a misnomer because they are hazard phrases but distinguishing between those 2 concepts is linguistically difficult elsewhere in Europe.You are of course free to make your personal assessment of risk with "My own impression about copper citrate is that it is relatively harmless compound".
(3) "From my own long industrial experience as research chemist I have found that most of risks assesments are rather political/legal documents of very limited value in real life".
From my long experience as a toxicologist in the chemical industry I have a different view.
(4) "Their [risk assessments] production is a great time wasting exercise and it is sometimes actually endangering health of workers because they are first forced to produce this nonsense to satisfy legal requirements"
As a past member of the HSE's Advisory Committee on Toxic Substances, I assure you the TUC, CBI and HSE members think otherwise.
(5) I also use dil HCl to remove Cu oxide.

"it is reproduced from literature"

Not really. Link specified by you is claiming explicitly "H315.(11.43%) causes skin irritation", *You* are claiming 93.75% contrary to link which you have submitted yourself. So perhaps read it again.

"R(risk) and S(safety) phrases are assigned to chemicals by concensus in an expert committee of the EU"

There are plenty of commities in the EU, unfortunately most of them entirely useless.

"As a past member of the HSE's Advisory Committee on Toxic Substances, I assure you the TUC, CBI and HSE members think otherwise."

Who cares what they think? Industry is moving production to China and elsewhere and they have nothing to say there. Bureaucrats you mention are one of many causes of pending economic ruin of West where everything is outsourced and only bankrupt banksters and hopelessly indebted public is left.

Martin

[AdrianRParticipant @adrianr18614]

I have just tried citric acid to clean up some rusty tool makers clamps, very impressed with the result. Actually it was Ecover toilet cleaner 1:4 with hot water.

I after scrubbing I soaked them in a solution of sodium bicarbonate to neutralise any remaining acid and then a light oil.

[Brian HParticipant @brianh50089]

I can vouch for the Frosts rust remover. I foolishly did some major silver soldering in the workshop and all unprotected steels went rusty.

I soaked a couple of items in Frosts, wiped them with a tissue, washed them in water and immediately sprayed on some WD40.

The items cam out a matt grey colour but free of rust.

Brian

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