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1st Apr 2019, 11:47 am | #1 |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
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Zinc plate and passivate? Restoration.
Picked up a "linear" amplifier.
Front panel looks OK and it needs a good de-dusting. but the back panel could do with a light restoration. Is it zinc plated and passivated and is there a receommended method of restoration? I'm thinking alng the lines of some sort of coloured lacquer ( I'm sure you could get something similar for restoring the finish on carburettors ) rather than completely dismantling the unit and getting the panel re-plated. |
1st Apr 2019, 5:07 pm | #2 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,935
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Re: Zinc plate and passivate? Restoration.
I'm not sure that I've heard of a passivation process being applied to a zinc coating. Perhaps more likely, the platers had some tricks up their sleeve to get a zinc plating with a specific look.
Most carburettors are made of aluminium alloys; I don't think I've seen one with zinc plating. There are kits on the market to carry out plating by means of a cotton swab on the end of a graphite rod, that is dipped in a plating solution and then used to do electroplating. I've seen quite good results from them, especially when the area is small as in your case. They may well be worth a try. B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
1st Apr 2019, 7:58 pm | #3 |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
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Re: Zinc plate and passivate? Restoration.
This was the stuff I was thinking of. Supposed to replicate zinc chromate
https://www.frost.co.uk/eastwood-bro...SABEgJfvPD_BwE |
1st Apr 2019, 8:57 pm | #4 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,935
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Re: Zinc plate and passivate? Restoration.
So, the Eastwood stuff is an acrylic paint which looks like zinc chromate. I wonder how closely it will match?
If you are going to remove the existing zinc with carbide paper or whatever, I guess that will get you down to to plain steel. As you don't have endure the under-bonnet conditions of temperature and petrol, I wonder if you could find something cheaper than £16, perhaps something from the model paint people like Humbrol (who have a metallic bronze). I'm not too sure that any paint will give a really close match to real zinc plate, but guess it depends on how demanding you are . B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
1st Apr 2019, 11:40 pm | #5 |
Heptode
Join Date: Feb 2011
Location: Southend, Essex, UK.
Posts: 803
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Re: Zinc plate and passivate? Restoration.
Unless things have changed I thought a zinc plated finish could either have a clear or coloured passivated finish applied?
Might be worth asking a platers Alan |
2nd Apr 2019, 3:26 am | #6 | |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,935
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Re: Zinc plate and passivate? Restoration.
Quote:
The terminology is a bit loose; a more formal description of passivation is as per Wiki https://en.wikipedia.org/wiki/Passivation_(chemistry) but we start to get in to splitting hairs over passivation and inhibition. For an object which lives in a environment which is not very corrosive, I think you'd expect standard zinc coating to be satisfactory. B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
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4th Apr 2019, 8:47 pm | #7 |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
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Re: Zinc plate and passivate? Restoration.
Linear arrived tonight. Opted for citric acit derust (lemon juice), Brasso, and hard paste wax.
Will do a restoration post in success stories if 80’s kit is deemed vintage / interesting enough |
4th Apr 2019, 11:05 pm | #8 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,935
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Re: Zinc plate and passivate? Restoration.
That looks really good. A re-visit with the wax every blue-moon might well keep it that way!
B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
6th Apr 2019, 8:21 pm | #9 |
Nonode
Join Date: May 2016
Location: Cornwall, UK.
Posts: 2,339
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Re: Zinc plate and passivate? Restoration.
That's made a real difference - it's easy to see where the tissues were (I assume soaked in lemon juice?)
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6th Apr 2019, 8:42 pm | #10 |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
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Re: Zinc plate and passivate? Restoration.
Yes, an hour in lemon juice, brought the rust pits back to grey steel
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7th Apr 2019, 12:28 am | #11 | |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,935
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Re: Zinc plate and passivate? Restoration.
Quote:
B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
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24th Apr 2019, 7:01 pm | #12 |
Nonode
Join Date: May 2016
Location: Cornwall, UK.
Posts: 2,339
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Re: Zinc plate and passivate? Restoration.
My mother had great difficulty getting citric acid a few years ago for some preserves. The shopkeeper said that apparently there was some control of it because of its propensity to get cut with cocaine!
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24th Apr 2019, 8:00 pm | #13 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,935
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Re: Zinc plate and passivate? Restoration.
Never had any problems, either on the High Street or ebay.
Used some citric yesterday to clean up a small mild steel bracket which was rusty in some places and covered with zinc plate in others. Cooked it up to about 50°C, and after about an hour, both the rust and the zinc were gone leaving a very a really nice surface to paint with primer. B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
24th Apr 2019, 8:40 pm | #14 |
Triode
Join Date: May 2008
Location: Chorley, Lancashire, UK.
Posts: 16
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Re: Zinc plate and passivate? Restoration.
That's a good Linear I have one of those, very clean output and the preamps a boon
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