MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Removing corrosion

Not strictly Spridget related, but corrosion is corrosion! In this case it is on the battery contact terminals in a Cannon photo flash unit. It takes 4 AA batteries which have been left in and resulted in the typical blue corrosion on the metal contacts. I've been asked if I can clean it up. The contacts in question are down inside the battery compartment and quite hard to get at so difficult to use an abrasive of any sort.

I was thinking maybe a chemical solution would be better applied with a cotton bud swab as the best way to deal with it, but what product to use? It's quite an expensive item I don't want to damage it furthur!
GuyW

White vinegar and a small fibreglass brush for the hard to reach bits?
Jeremy MkIII

Thanks Jeremy, do you think vinegar will do it? Not doubting you!
I do have a variety of solvents, metal cleaning solutions, meths, thinners and phosphoric acid 5%, in the garage but am a bit wary of using something too fierce. The corrosion has produced a blue "furriness" which I am guessing suggests the contacts are brass, though they look shiny so must have a plating. I dont think they are anything special, just what one gets on most such battery contacts, but would be difficult to replace. I need something to gently clear the blue growth that can then be removed or neutralized so it doesnt continue to consume the contacts.
GuyW

Most acids including vinegar will help. I used some stuff called TCA once that was in the bathroom. It's meant for killing verrucas, of all things!
A good tip I've learned is to make a paste with the acid and some flour, which you can apply with a small brush and being a paste it stays where you put it. When it dries you can pick it out with a pointy thing, hopefully with the corrosion product attached.
Jeremy alluded to a fibreglass brush and quite right too... those things are brilliant. They're cheap and easy to get from electronic shops. I have several in different sizes but they are essentially like a pen which you twist to expose a small bundle of glass fibres. Specifically designed for cleaning small electrical contacts and very effective indeed.
Admittedly I'm careful about removing the glass debris though.
Greybeard

TBH Guy I YouTube'd it and the consensus was white vinegar as it seemed to be common to quite a few videos.
Maybe it's the least abrasive solution to start with and then move onto stronger substances ...to clean the corrosion - although alcohol may help both!
Jeremy MkIII

Ok, white vinegar it is then! I will try that and see how it goes. Good idea about making up a paste too Rob.
GuyW

Guy
Maybe try dipping the nd of your bud into some boiling water and give the terminals a go with that--boiling water is the best thing going for car battery terminals.
Then you could apply some automotive radiator rust inhibitor (coolant) on a bud. It works fantastic on car battery terminals-- to stop them recorroding

willy
William Revit

Thanks for that suggestion Willy
GuyW

Have you considered switch cleaner? I think it is formulated to remove corrosion from electrical contacts.

Jan
J Targosz

Just to complete this story.
I used white vinegar. It worked quite well, though slowly, to remove the blue residues (copper sulphate crystals ??) . I then used contact cleaner though that made no visible difference. Where the blue had gone there remained a small amount of black which I assume is actually rust or some sort of iron based compound? I am not a chemist! It does however conduct electricity as the flash gun now works again.☺ I applied a gnat's whatsit of electrical grease to the terminal to stop the black from spreading.

There was another problem though. On one contact the corrosion had actually eaten through the lower bend in the Z shaped metal contact which provides the springiness to the battery contact terminal. Down in the depths of the battery box I couldn't access to solder it back on. I therefore made a new contact from a small 6x9mm brass base to which I soldered a small coil spring. The brass sits on top of the remains of the terminal and the battery now presses nicely onto the coil spring to hold it all in position and complete the circuit.☺☺
GuyW

This thread was discussed between 08/12/2022 and 10/12/2022

MG Midget and Sprite Technical index

This thread is from the archives. Join the live MG Midget and Sprite Technical BBS now