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Cabinet and Chassis Restoration and Refinishing For help with cabinet or chassis restoration (non-electrical), please leave a message here. |
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15th Jun 2006, 12:25 pm | #1 |
Pentode
Join Date: Jun 2006
Location: Malaga, Spain.
Posts: 235
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Battery acid corrosion
What is the best way to stop corrosion of an aluminium chassis caused by acid from dry cells? I have tried cleaning and soaking in a bicarb solution but after a couple of days the white deposit returns.
Cheers, Boiss |
15th Jun 2006, 1:13 pm | #2 |
Triode
Join Date: Oct 2005
Location: Southampton, Hampshire, UK.
Posts: 46
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Re: Battery acid corrosion
Try, Hammerite rust remover it is excellent! Goeff
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15th Jun 2006, 4:51 pm | #3 |
Retired Dormant Member
Join Date: Sep 2003
Location: Bristol, UK.
Posts: 808
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Re: Battery acid corrosion
I have a recollection that Aluminium is attacked by caustic soda. It might well react with other alkalis as well.
This could explain the white deposit. Incidentally do the dry cells have an acid electrolyte? If it is alkaline, then vinegar may help. I seem to remember that boiling fruit in an aluminium saucepan makes it nice and shiny. |
15th Jun 2006, 6:14 pm | #4 |
Pentode
Join Date: Jun 2006
Location: Malaga, Spain.
Posts: 235
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Re: Battery acid corrosion
The problem was started by acid from old dry cells ( Sal Ammoniac?) I cleaned the chassis with a wire brush and dremel etc and then left it in a bicarbonate of soda solution for a couple of days. Then washed it with warm soapy water. After about 2 days there were signs of white deposits again. I have now soaked it in WD40 but I am not convinced that this will cure it. the copper and brass bits are fine after the bicarb treatment. They were not put in the solution together and the solution used was not very strong.
I was wondering if anodising it might be a better long term cure. Cheers, Boiss. |
15th Jun 2006, 6:19 pm | #5 |
Retired Dormant Member
Join Date: Dec 2003
Location: North London, UK.
Posts: 6,168
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Re: Battery acid corrosion
Freshly cleaned aluminium forms a thin oxide film within minutes (seconds?) of being exposed to air. Anodising is the process of thickening this film by an electrolytic process. Ali actually corrodes very readily. It's only the oxide film that stops it corroding away to nothing.
I suspect that the white deposit is a carbonate or chloride. I'm afraid my chemistry runs out about there. |
15th Jun 2006, 8:34 pm | #6 | |
Retired Dormant Member
Join Date: Feb 2005
Location: Monmouthshire,on South Wales border
Posts: 85
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Re: Battery acid corrosion
Quote:
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16th Jun 2006, 12:14 am | #7 |
Dekatron
Join Date: Jan 2003
Location: Bradford on Avon, Wiltshire, UK.
Posts: 3,310
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Re: Battery acid corrosion
I have used vinegar on a cotton bud or toothbrush. I suspect Tomato Ketchup would work well too( very good for cleaning coins).
Take care to wash the vinegar off afterwards and tin the contacts. Cheers Tim
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"Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly." Last edited by Darren-UK; 2nd Sep 2007 at 12:46 pm. Reason: Relevant typo corrected. |
16th Jun 2006, 5:47 am | #8 | |
Octode
Join Date: Jan 2004
Location: Southport, Merseyside, UK.
Posts: 1,156
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Re: Battery acid corrosion
Quote:
Are these copper and brass bits in physical contact with the aluminium? If so, that could be a cause, they form a galvanic cell, and aluminium being the most electro-negative of the two will corrode away. Regards John. |
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16th Jun 2006, 1:57 pm | #9 | |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,580
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Re: Battery acid corrosion
Quote:
Rich.
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21st Jun 2006, 6:38 pm | #10 |
Pentode
Join Date: Jun 2006
Location: Malaga, Spain.
Posts: 235
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Re: Battery acid corrosion
OK, Thanks for the help, the vinegar appears to work a treat. That was a bad mistake putting it in bicarb solution. If it had been left another year or two it would have been unuseable (just powder.) I will lacquer the chassis part in an attempt to halt any further corrosion.
Thanks again, Boiss Last edited by Darren-UK; 2nd Sep 2007 at 12:47 pm. Reason: Reference to non-existent image removed. |