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I am currently building a Micheline railcar in EM. These things had rubber tyred wheels.

 

Fortunately the wheel treads are mostly hidden by splashers that come down quite low, but I was thinking that I might chemically blacken some steel tyred wheels to hide the steel glint that might otherwise be apparent.

 

I haven't looked into the chemistry of what the blackened surface actually is, but it raises two questions:

 

1. Is it electrically conductive after blackening, or does the surface become insulating?

 

2. Is the surface layer robust - is it likely to come off with normal running and cleaning?

 

Cheers,

Simon.

Edited by sharris
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Try gun blue, it ends up shiny black, conducts and is fairly robust. Available off ebay, or a local gun shop.

 

Wash and degrease the bits to be blackened carefully, dry without touching with your hands.

 

Apply the gun blue with a cotton bud etc, allow to dry and buff up with another cotton bud. finally wash off any residue, and dry again.

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Eileen's Emporium sell gun blue. They have it either in a jar - suits the cotton-bud technique - or in a pen.

 

By my experience, it doesn't work on some steels. It won't blacken the tyres on Exactoscale wheels, for instance (I think they may be made of stainless steel).

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The stuff I bought from Eileens is of American manufacture, by an outfit named Birchwood Casey. It is a liquid, whereas the only Gun Blue I've had from a gun shop has been a paste.

 

With the liquid, wet a cotton bud and rub the surface to be blackened. As Jeff says the surface receiving treatment needs to be completely clean, and any grease at all messes up the blackening process. Afterwards wash off, I usually wipe with a damp rag or cotton bud.

 

The fluid comes in several varieties, and strangely enough I've found the one supposedly for brass is less effective on brass than ones for other metals. It leaves a grey-brown patina on the treated item, rather than someting actually black, but is highly effective in toning down bright metal, and looks particularly good in my opinion on valve gear, provided the post application washing has been thorough (otherwise it can cause the valve gear to seize up!)

 

Be a little careful using the stuff, you only need a bit on a cotton bud, and whilst not wishing to sound preachy do make sure you wash hands very thoroughly afterwards.

 

John.

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Does anyone know if the chemical blackening from Birchwood casey going to react with plasticard?  I have some 7mm wagons which came with brass couplings.  I was going to blacked them, but one looks like it could be a right pain to remove the couplings first.

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Does anyone know if the chemical blackening from Birchwood casey going to react with plasticard?  I have some 7mm wagons which came with brass couplings.  I was going to blacked them, but one looks like it could be a right pain to remove the couplings first.

I'm sorry to say I don't have a definitive answer to your question, and quite possibly the answer in any case is that it depends on the type of plastic.

 

You could try rubbing a tiny bit on the underside of the wagon to see what happens.

 

In my own use of the stuff you don't apply much and it can be quite controlled - its not as if there needs to be immersion or anything like that.  You could perhaps cover the adjacent plastic surfaces with low tack masking tape to give a bit of protection, and then just apply sparingly to the coupling with a cotton bud that has been dampened but not saturated with the blackening fluid.

 

John.

Edited by John Tomlinson
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Does anyone know if the chemical blackening from Birchwood casey going to react with plasticard?  I have some 7mm wagons which came with brass couplings.  I was going to blacked them, but one looks like it could be a right pain to remove the couplings first.

 

Should be fine, I've blackened a few things in situ on plastic wagons and the like and nothing has disintegrated yet. 

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  • 3 weeks later...

I've been using Birchwood Casey blackening fluids for years and as far as I can tell, the various types (Steel, Brass, Aluminum) have no adverse effect on plastics or anything else, for that matter. 

Be aware they are all toxic and have 'Poison' written on the bottles. 

 

There is a stainless steel blackening fluid made by www.caswelleurope.co.uk/stainless-steel-blackener-500ml/ and although quite expensive, is the only effective method of darkening the metal. I use it to darken stainless steel wheels on 7mm scale RTR locomotives made in China and Korea. Again, it's not to be inhaled or imbibed - its pungent smell should act as a warning.

 

Hope this is of some help.

 

Martyn

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  • 4 years later...
  • RMweb Premium
On 25/05/2016 at 00:41, Weatherman said:

I've been using Birchwood Casey blackening fluids for years and as far as I can tell, the various types (Steel, Brass, Aluminum) have no adverse effect on plastics or anything else, for that matter. 

Be aware they are all toxic and have 'Poison' written on the bottles. 

 

There is a stainless steel blackening fluid made by www.caswelleurope.co.uk/stainless-steel-blackener-500ml/ and although quite expensive, is the only effective method of darkening the metal. I use it to darken stainless steel wheels on 7mm scale RTR locomotives made in China and Korea. Again, it's not to be inhaled or imbibed - its pungent smell should act as a warning.

 

Hope this is of some help.

 

Martyn

Hi Martyn,

I'm looking for a stainless steel blackener, as Markits wheels are now being made from stainless instead of Nickel Silver.

Just checked that out that link;  now its here:  https://www.caswelleurope.co.uk/metal-patina-process/?sort=featured&page=2 

One litre is a bit too much just for a few wheels, especially at £72! 

Any idea if can it be had in smaller quantities?

Cheers, Dave.

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