Treating corrosion from leaked cells

[Phil G4SPZ]

I'm restoring a WWII-era Record Bond Tester which has suffered badly from battery leakage. The original battery was a single alkaline (NiFe) 1.2 volt rechargeable cell. The corrosion has eaten away much of the internal wiring and has tracked along as far as the movement itself.

The pictures show the sorry state of the connections to the movement, which - amazingly - still works. I would like to remove this corrosion and stabilise the conductors to ensure that it doesn't keep insidiously creeping back, as this type of corrosion is prone to do if not completely removed.

With the cell being alkaline, I'm assuming that the corrosion itself is alkaline in nature, so could it be removed by carefully brushing on a dilute acid, such as vinegar or lemon juice, with a modeller's paintbrush and washing off with distilled water? Or does anyone have any other recommended solutions? All advice welcome!

Phil

[MrBungle]

Vinegar and distilled water is what I use when this happens. Takes a while and irritates the nose but it's surprising how good the stuff is.

[Phil G4SPZ]

Good-oh, thanks Mr B and I'll give it a go.

[emeritus]

Yes, vinegar works fine. I have an old pickled onion glass jar that I keep vinegar in for this sort of thing. I apply with an artist's paint brush or cotton bud until the fizzing stops, and wash off with tap water, then blow dry using the BLOW facility of an old cylinder vacuum cleaner. Must have dealt with this dozens of times, especially when the kids used to buy what had been expensive, but non-working, battery-powered toys with corroded batteries for pennies at school jumble sales. Vinegar worked every time.

[TonyDuell]

I use a strong-ish solution of citric acid (sold for home brewing or winemaking, I think, at least that's where it is stocked in the local Wilkinsons). It doesn't irritate my nose like vinegar does.

The electrolyte in NiFe (and NiCd) cells is potassium hydroxide solution. Often the corrosion is potassium carbonate (it reacts with CO_2 in the air). It will fizz a bit when you put the acid on, but that is nothing to worry about. The green corrosion is probably some copper salt, which will disolve in the weak acid too.

[Boater Sam]

Copper nitrate and copper sulphate ( is it to be sulfate now?) Mostly through the fumes of the hydroxide attacking other metal parts.
Will dissolve, you can't always do it but a dishwasher works wonders.
Sulphuric acid corrosion is much harder to neutralise.

[Phil G4SPZ]

Excellent, thanks for all the advice.

As the corroded item is a moving coil meter movement, I'll pass on the dishwasher idea, Sam!

[poppydog]

I cleaned a metal battery holder in a Murphy B495 that I thought had had it the other day, in a bath of white vinegar. It came up really well. The white vinegar is purer/stronger and does a far better job.
regards poppydog

[Sinewave]

I use a fibre glass pen to remove what I can, then clean the contacts up by brushing on some ACF-50.

[Phil G4SPZ]

I eventually used a 50:50 mixture of white vinegar and lemon juice, something I've used previously for cleaning intricate brass parts on vintage oil lamps. I applied it with an small artists' brush, left it a few moments and washed it off with hot boiled water. Not a perfect end result I confess, but a lot better than what I started with.

I was interested in the ACF-50 but the price rather put me off...

Thanks for the all interest and advice.

Phil

[Refugee]

That has cleaned up nicely.
Well done.

[Sinewave]

Originally Posted by Phil G4SPZ

I was interested in the ACF-50 but the price rather put me off...

It is expensive, however it really is worth every penny of it's cost - it really is that good.

But you've done a good job of cleaning those terminals up.

[Bazz4CQJ]

Originally Posted by Phil G4SPZ

I eventually used a 50:50 mixture of white vinegar and lemon juice, something I've used previously for cleaning intricate brass parts on vintage oil lamps. Phil

So in reality, some acetic acid and some citric acid, both (but mainly the latter) being previously recommended on here (multiple times over the years) as very good chelating agents and just right for the job...and they still are.

B

[Phil G4SPZ]

Well, my original question was a simple one, but as always with the Forum, I've learned a lot more than I expected!

[stevehertz]

One can debate the best chemical to remove battery leakage and oxidisation, but these can themselves cause further damage, leave residues etc. These days I only use mechanical methods to remove the problem. I have a collection of tools comprising small brass and steel brushes, tooth brushes, fibre glass pen, impregnated rubber blocks etc etc. Then I follow up with a coating of Servisol either sprayed on or brushed depending on the application.

[Herald1360]

^^^WHS^^^

Except I use silicon grease afterwards.

[Bazz4CQJ]

Originally Posted by stevehertz

One can debate the best chemical to remove battery leakage and oxidisation, but these can themselves cause further damage, leave residues etc. These days I only use mechanical methods to remove the problem. I have a collection of tools comprising small brass and steel brushes, tooth brushes, fibre glass pen, impregnated rubber blocks etc etc. Then i follow up with a coating of Servisol either sprayed on or brushed depending on the application.

Sounds a bit like you don't believe in the rationale approach of science then, or at least not in chemistry? Your assertion that "one can debate the best chemical...but..." is most likely to be true when none of the participants in the debate are chemists. For the most part, this is neither Witchcraft nor Rocket Science. I suspect that in places like the Science Museum, this is frequently the task assigned to fairly junior technicians who simply look the problem up in their procedures manual.
B

[ColinTheAmpMan1]

Originally Posted by Boater Sam

...copper sulphate ( is it to be sulfate now?)

No, not while I still draw breath, anyway. Unfortunately there are a lot of Americans and they have made a pretty good job of mangling the English language. Fair enough for them, but it is the English language, after all. They have had a go at the ancient Greek alphabet, too. "Bayter" indeed!
Colin.

[dseymo1]

In general I agree with your sentiment, but in this case the official spelling has indeed been standardised to 'f', which for once is etymologically correct.

[Bazz4CQJ]

Well.... when did that happen? I just looked it up and looks like IUPAC gone done it.

B