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Author Topic: Old chassis sheet metal  (Read 966 times)
ZS1ZC
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Posts: 4




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« on: October 19, 2018, 01:54:09 AM »

What is the process used in boatanchor chassis that gives the steel that light golden-yellow look? Is it zinc anodizing of some sort? I have some that was so corroded I had to strip it right back, but now of course  I'm looking at bright silver. Best I can think of for corrosion prevention is clear enamel, but it would be nice to get the same look as before.

73,
John ZS1ZC.
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KAPT4560
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Posts: 550




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« Reply #1 on: October 19, 2018, 02:29:47 AM »

 It is likely an MFP (moisture and fungal protectant) varnish. You can Google for information about it:
 https://rec.antiques.radio-phono.narkive.com/p7bb5Aoy/moisture-proofing-military-radios

 I see a tradename of Hysol®, but I don't know if it is the vintage tinted protective coating that was originally used.
 I do conformal coating of finished circuit boards at work. It is a clear polycarbonate coat that cures under UV light.
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VU2NAN
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« Reply #2 on: October 19, 2018, 03:35:45 AM »

What is the process used in boatanchor chassis that gives the steel that light golden-yellow look? Is it zinc anodizing of some sort? I have some that was so corroded I had to strip it right back, but now of course  I'm looking at bright silver. Best I can think of for corrosion prevention is clear enamel, but it would be nice to get the same look as before.

73,
John ZS1ZC.

Hi OM John,

It's Zinc plating with yellow passivation.

Zinc plating by itself is bright and silver colored. Chromate conversion coatings are applied on the zinc plating for increased corrosion resistance. They are available in blue, yellow, olive-green, black etc. colours. Another name for  chromate conversion is passivation.

73,

Nandu.
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KE4OH
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Posts: 221




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« Reply #3 on: October 19, 2018, 06:32:37 AM »

Cadmium plating was very common on steel chassis and imparts a yellowish tint. Cadmium is pretty much a bad actor if you ingest it, whereas zinc isn't too bad. So unless you can tell the difference between zinc and cad plating, take care not to breath any filings/dust if you decide to use medieval methods (like sanding, scraping, steel wool, etc.) to clean the chassis.
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73 de Steve KE4OH
W8RXL
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Posts: 70




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« Reply #4 on: October 19, 2018, 06:38:35 AM »

I have not seen this used in a lot of radio equipment but it is a dichromate coating. There are paints that mimick it from Eastwood restoration supply company that I've used on carbs and other underwood components, so I assume that it would be alright for radios.
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G3RZP
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« Reply #5 on: October 19, 2018, 08:12:03 AM »

Quote
Cadmium is pretty much a bad actor if you ingest it,

KE4OH is right.

'Cadmium plate and passivate' was the term used to specify the finish - at least, in the UK, and it produces a yellow colour.

It is highly recommended to carefully wash your hands after handling cadmium plated parts. There's a village in UK West Country where the levels of cadmium salts in the soil are so high that you are not supposed to grow vegetables for food there.
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AE5GT
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« Reply #6 on: October 19, 2018, 09:24:41 AM »

Cadmium is still in common use ,especially on grade 8 steel hardware (farming equipment ect. ) . You also find it used in some "marine" fresh water applications as a cheap alternative to galvanize.
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KM1H
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Posts: 4772




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« Reply #7 on: October 19, 2018, 09:44:27 AM »

Military and some commercial radios used MFP. Ham/consumer

Carl grade used cadmium plating or nothing. I havent heard of anyone getting sick from scrubbing any radio chassis as the exposure is minimum when a bit of water is included.

Carl
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G3RZP
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« Reply #8 on: October 20, 2018, 12:55:05 AM »

The effects are cumulative, although even a short term exposure to cadmium dust can lead to problems. Realistically, especially as this is only occasional exposure, use plenty of water so there isn't any dust and wash your hands carefully after handling. Then handling cadmium plated boat anchor chassis is nowhere near as dangerous as driving.
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KM1H
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« Reply #9 on: October 20, 2018, 09:51:18 AM »

I meant to say Consumer Grade!!
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N3DT
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« Reply #10 on: October 20, 2018, 03:20:03 PM »

There's also anodizing. But I don't know anything about it. I remember this company I worked for would anodize their chassis and it looked very yellow, almost gold colored.
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KM1H
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« Reply #11 on: October 20, 2018, 03:33:18 PM »

On aluminum
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G3RZP
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« Reply #12 on: October 21, 2018, 01:11:36 AM »

Anodising  on aluminium leaves a non-conducting film, so it's a PITA to make grounding connections to.
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KM1H
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« Reply #13 on: October 21, 2018, 08:35:37 AM »

Then use Alodine altho SS star washers do well on anodized, just dont use rivets.
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