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Old 4th Dec 2018, 1:44 pm   #1
jamesinnewcastl
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Default Restoring WW2 Junction Box - confused?

Hi All

I've just started to take the paint off of a small SBA junction box and at first was greeted by a shiny copper/brass colour. But going deeper into some heavy pitting the colour gives way to silver, I checked and that is true for the whole box.

Is coating a steel box with copper/brass a common practice?

Was it done for corrosion reasons (didn't work)?

Was it done for conductivity/shielding reasons?

I need to 'fill' in the deeply pitted sections or they will look ugly after painting - what is the best method for this (after passivating the rust). I am worried that the filler will just fall or crack out.


Cheers
James
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Old 4th Dec 2018, 2:23 pm   #2
ex seismic
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Default Re: Restoring WW2 Junction Box - confused?

I don't think car body filler will fall out, after all it is designed to withstand vibration which you won't be subjecting it to. If you are worried that your pitting isn't deep enough for a good key then just drill holes in the pitted area which will let you form a "blob" on the inside which will hold on better. I did a large repair on a Landrover wing like that which vibrates and flexes in use. Nothing fell out.

Gordon
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Old 4th Dec 2018, 4:32 pm   #3
Silicon
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Default Re: Restoring WW2 Junction Box - confused?

I hope it is not Cadmium plating. It is regarded as being toxic.
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Old 4th Dec 2018, 6:18 pm   #4
M0FYA Andy
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Default Re: Restoring WW2 Junction Box - confused?

Quote:
Originally Posted by Silicon View Post
I hope it is not Cadmium plating. It is regarded as being toxic.
It won't be once it's painted, just take sensible precautions cleaning the box up, don't breathe in the dust and wash your hands before eating!

Andy
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Old 4th Dec 2018, 6:22 pm   #5
G6Tanuki
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Default Re: Restoring WW2 Junction Box - confused?

For metal that's deeply pitted but not rusted-through, my approach is to 'pickle' it in something aggressive to make sure all the rust is _really_ removed from the bases of the pits, then first 'mist' over lightly with an acid-etch primer followed by layering-on several coats of high-build primer, sanding down in between each coat, until the pits are filled.

Then leave the item somewhere hot [I use the flue-pipe of my combi-boiler] for a few weeks. Why? Because the primer will still shrink slightly! Then another couple of coats of high-build with more sanding and the job's ready for the topcoat.

Etch-primer and high-build primer are available cheaply in 'rattle-cans' from these guys: https://www.u-pol.com/
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Old 5th Dec 2018, 8:59 am   #6
jamesinnewcastl
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Default Re: Restoring WW2 Junction Box - confused?

HI Guys

Thanks for the replies. I know that cadmium colour and it isn't that - it's very like copper plumbing pipe colour. I've had a Google and it seems that copper coating steel isn't uncommon but it just seems a bit extreme for a junction box.

However it also seems that steel doesn't take paint well so perhaps the copper is just a primer?

This is at odds with my usual method of just spraying anything with any old paint..... mmm time for a rethink on that one then!


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James
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Old 5th Dec 2018, 9:39 am   #7
M0FYA Andy
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Default Re: Restoring WW2 Junction Box - confused?

I'm familiar with the Junction Box James refers to, and I agree that it is copper-plated.

I don't know why, maybe because wartime production was shared out to all sorts of industries to make things they had never made before, and whatever this company normally made before the war was copper-plated, so they just followed their normal practice and it was accepted by the Air Ministry.

Andy
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