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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 11th Apr 2024, 5:41 pm   #1
line sync
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Default Cleaning metalized valves.

Many times I've come across a valve with a dirty metalized coating and despite trying many things over the years i can only make a small improvement.
The valves in question would have stopped being made about 1955 and would be British 4 pin & 5 pin ,side contact and octal,s to name a few.
I've got a mazda T41 and DD41 that test good but they are very dirty , does anyone know a good way of cleaning them ?

Robin
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Old 11th Apr 2024, 7:30 pm   #2
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Default Re: cleaning metalized valves

It's often the case that a good ultrasonic cleaner (with a good cleaning additive) will work wonders when all else has failed, but I've never put a valve in one.

Are you sure that what you are referring to as dirt is not actually some deterioration of the surface coating (I'm not familiar with these valves) which is effectively irreversible? Maybe a pic or two would be useful?

B
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Old 12th Apr 2024, 9:25 am   #3
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Default Re: Cleaning metalized valves.

I agree with Bazz it's the coating that deteriorates I have tried cleaning them in the past to no avail, I did once try a light dusting of the appropriate colour taking care around the printing this improved the look. Mick.
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Old 12th Apr 2024, 1:45 pm   #4
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Default Re: Cleaning metalized valves.

Thank both for the reply's
I don't have an ultrasonic cleaner so cannot try that.
I agree alot of the times the coating has deteriorated or flaked off due to damp and in these cases little can be done.
In my case the valves are grubby and have heat marks.
I will try to photograph this later .
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Old 12th Apr 2024, 3:13 pm   #5
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Default Re: Cleaning metalized valves.

I'd try Servisol 30 foam cleanser with a toothbrush. It's my 'go to product' for cleaning most things, and mostly it's successful.
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Old 12th Apr 2024, 3:41 pm   #6
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Default Re: Cleaning metalized valves.

I have used Ambersil foaming car upholstery cleaner to get the gunge off a bunch of the red Mullard Octals I acquired as unboxed water damaged stock (black mould included) a while back.

I would only suggest using water based cleaner, organic solvents might lift the metallised coating and remove any printed labelling.
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Old 12th Apr 2024, 6:10 pm   #7
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Default Re: Cleaning metalized valves.

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Originally Posted by G6Tanuki View Post
I have used Ambersil foaming car upholstery cleaner to get the gunge off a bunch of the red Mullard Octals I acquired as unboxed water damaged stock (black mould included) a while back.

I would only suggest using water based cleaner, organic solvents might lift the metallised coating and remove any printed labelling.
Red Mullard valves tend to have a shiny finish that is easier to clean than the more 'rough' finished silver-grey Mazda ones that seem to cling on to grime.
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Old 12th Apr 2024, 7:41 pm   #8
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Default Re: Cleaning metalized valves.

Once you've got the coating as clean as possible, and assuming its adhesion is good, you could try rubbing in a little 'wax gilt' of appropriate colour.

Steve
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Old 12th Apr 2024, 8:11 pm   #9
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Default Re: Cleaning metalized valves.

I just tried servisol foam with a tooth brush and I'm sorry to say it didn't work Steve.
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Old 12th Apr 2024, 9:08 pm   #10
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Default Re: Cleaning metalized valves.

I wonder what would happen if you tried to perform electrolysis on them?
Many people clean rust off steel using electrolysis. Think the first valve would have to be something you were prepared to spoil.

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Old 13th Apr 2024, 1:14 am   #11
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Default Re: Cleaning metalized valves.

Quote:
Originally Posted by line sync View Post
I just tried servisol foam with a tooth brush and I'm sorry to say it didn't work Steve.
Have I misunderstood you? Have you tried a wax gilt obtainable in a tube from art shops? If you rub it in over that surface with a finger, you should see a dramatic improvement. I used to use the 'antique gold' shade. Silver is also available.

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Old 13th Apr 2024, 8:22 am   #12
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Default Re: Cleaning metalized valves.

If the adhesion is good have you tried isopropol etc, bleach or petrol? I've found bleach watered down a bit in warm water, applied with an old toothbrush cleans most gunk off.

Andy.
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Old 13th Apr 2024, 8:53 am   #13
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Default Re: Cleaning metalized valves.

Quote:
Originally Posted by Panrock View Post
Quote:
Originally Posted by line sync View Post
I just tried servisol foam with a tooth brush and I'm sorry to say it didn't work Steve.
Have I misunderstood you? Have you tried a wax gilt obtainable in a tube from art shops? If you rub it in over that surface with a finger, you should see a dramatic improvement. I used to use the 'antique gold' shade. Silver is also available.

Steve
His response was to me Steve. See my earlier post.
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Old 13th Apr 2024, 9:05 am   #14
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Default Re: Cleaning metalized valves.

Thanks Steve and my apologies. I must avoid using my phone to reply, since it prevents me getting a feel for the whole thread. S
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Old 13th Apr 2024, 1:26 pm   #15
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Default Re: Cleaning metalized valves.

Steve (panrock) i,ve not heard of wax gilt and if it works as well as you say then i must try some.
Andy , not tried any of the ones you suggest but we use isopropyl at work so can try that on monday.
Electrolysis is also another good idea.
I tried alloy wheel cleaner yesterday and it worked well.
I just applied a little on a small paint brush and it started fizzing straight away, i left it for about 30 seconds and rinsed the valve off with water.
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Old 13th Apr 2024, 2:47 pm   #16
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Default Re: Cleaning metalized valves.

Some alloy wheel cleaner is citric acid, other versions use alkalis.

I wonder if the stuff used for cleaning limescale off showers might work??
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Old 13th Apr 2024, 3:27 pm   #17
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Default Re: Cleaning metalized valves.

Its called Wonder wheels and just says it contains 5% non ionic surfactants.
I don't know what that means but there's lots of health warnings on the bottle and it smells horrible.
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Old 13th Apr 2024, 3:48 pm   #18
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Default Re: Cleaning metalized valves.

Citric acid is a very good "de-scaler" for some applications, note the term de-scaler rather than cleaner. It chemically reacts with metal corrosion products. But it is very mild and safe to use; think "lemon juice".

Mostly, the alloy wheel cleaners are horribly concentrated alkalis and generally unsuited for any type of restoration/preservation work... not particularly well suited to cleaning anything without causing some level of harm!

B
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Old 14th Apr 2024, 12:25 am   #19
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Default Re: Cleaning metalized valves.

Wonder Wheels used to contain Hydrochloric acid.
Not sure what it has now.
Hydrochloric acid is a great cleaner.
It is the basis for Traffic Film Remover for cleaning HGVs.
Only have to be careful to rinse off quickly on aluminium and stainless steel.
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Old 14th Apr 2024, 5:26 pm   #20
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Default Re: Cleaning metalized valves.

Quote:
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Hydrochloric acid is a great cleaner.
Hydrochloric acid is a great destroyer of metals. It really has no place in radio restoration. Chloride ions adsorb on metal surfaces, and once there, they are hard to get off and are likely to initiate corrosion even after water washing. The technical literature dealing with chloride-induced corrosion fills entire libraries.

I'd be very surprised if there is hydrochloric acid in TFR, which I think are mainly alkaline.

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