# Metallic color at front end of steam loco



## musicwerks (Jan 4, 2012)

Hi,

I have a burning question- why do amercian steam locos always spotting a metallic grey in front of the boiler? Similarly why is that piece below the cab always metallic grey too?

Refer to attached pic...

What Tamiya color do you guys use for the metallic part ? and also the engine black for the main body...

I am trying to airbrush my undecorated proto 2-8-8-2

Cheers


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## N scale catastrophe (Nov 18, 2012)

According to other members of the forum (previous discussion with TJ) , the grey/metallic paint on the boiler withstood higher temperatures and would not flake off like the black. I use bolt metal grey for all of the "silver" on my engines and midnight flat black (Citadel colors). I am not sure about the other part you mentioned however, sorry.


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## tjcruiser (Jan 10, 2010)

Ditto to N's comment, above. I learned about the silver paint (on real trains) from a prior discussion here on the forum ... not sure who first brought it up. I tried to do a quick search for the thread, but came up empty handed.

Anyone else add to the history / tech lesson?

I use simple off-the-shelf rattle can paint on most of my redos. Krylon flat or satin black would work well for a boiler shell like that. No experience with Tamiya or airbrush on my end, I'm afraid.

Keep us posted, 'werks!

TJ


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## Gansett (Apr 8, 2011)

Below the cab is the ash pan or so I was told. Why silver/gray I haven't a clue. Back then high temp paints were years away, not sure how different colors could withstand the heat.


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## StevenIsBallin (Jan 4, 2013)

I think its because dark pain absorbs the heat from the sun more than light paint. So they put light colored paint on the hotter parts of the engine because it absorbs less heat from the sun and therefore less likely to flake off.


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## Southern (Nov 17, 2008)

I agree that it was that those where the hotest part of the locomotive and the gray held up to the heat better. I dought that it had anytihng to do with the solor heating. I just use gray primer.


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## StevenIsBallin (Jan 4, 2013)

I think its partly due to solar heating because I dont see why silver paint would hold up any better to heat than black paint besides the color difference. If it has something special added to it then they could just add that to the black paint and paint the whole engine black. It also makes sense to me since you would want black paint which absorbs more heat to be on the boiler to help keep the water hot. Im no expert or anything but that just sounds the most logical to me.


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## tjcruiser (Jan 10, 2010)

If I recall, standard old-fashioned black paint would bubble-off in the high heat. The silver paint had something special in it (I forget what, exactly) that would allow it to adhere in the high-heat conditions of the boiler front / flue uptake.

TJ


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## wingnut163 (Jan 3, 2013)

remember (if your old enough to ) have radiators the house.silver paint made just for them. it was called radiator paint. it let the radiator give off as much heat as was possible. i would think that the engines did the same. to help control the heat. i helped re-tube a steamer at a sight seeing RR in CT at lime. there is not a lot of room between the face plate and the start of the tubes.


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## gunrunnerjohn (Nov 10, 2010)

What's confusing me is that for radiating heat, black is best. However, for absorbing heat, black is best also. 

I'm waiting to see if anyone finds the real reason for the different color paint.


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## Gansett (Apr 8, 2011)

In the later years of steam the silver painting appeared to be abandoned.
NYC Mohawk in 1948 So it'll remain a mystery for now...


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## StevenIsBallin (Jan 4, 2013)

Maybe we're all just over thinking it and they just did it because it looked good at the time. lol


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## santafe158 (Jul 14, 2010)

Only a few road used silver high temp paint on their smokebox fronts. The rest weren't actually paint. It was a mix of graphite and linseed oil that would protect the metal against rust while being able to withstand the high temps. The spot in the rear by the cab would be the firebox. Depending on the ratio of Graphite to oil used, you'd get darker or lighter colorings.

Several railroads (such as the Santa Fe) ran the boiler insulation and sheetmetal all the way to the front of the smokebox and just used the graphite mixture on the very front. Most static displays just use paint to simulate the graphite/oil.

An example of a painted smokebox front (though i believe the sides and stack are still the graphite/oil)









Graphite/Oil smokebox


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## EMD_GP9 (Jun 19, 2012)

In the model engineering world heat resisting paint is often used on hot parts such as the smokebox and firebox ( the part under the cab ).
As this is often aluminium based it is usually siver or silver grey coloured.
I assume the same is true on full scale locomotives.
The same can be used on motor vehicle exhaust manifolds for the same reason.

Hope this helps, Colin.


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## tjcruiser (Jan 10, 2010)

SantaFe,

I think you pegged it ... at least from my fuzzy memory ... the graphite mix ... I think that's what we had discussed here a while back.

Thanks,

TJ

PS -- John, I remember my old Science teacher telling us students that we should all go home and paint our cast-iron radiators BLACK for better efficiency. He was right, of course. Wouldn't win any home decorating awards, though!


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## gunrunnerjohn (Nov 10, 2010)

That's the reason that high efficiency heatsinks are black for efficient radiation, and for the other direction of heat transfer, solar heating arrays as well are black.


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## BK R (Dec 8, 2012)

Radiators in trucks and cars are black too.


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## tjcruiser (Jan 10, 2010)

Good point. And, let's not forget the importance of summer-white attire in the sticky doldrums of July. Mine, at least ...


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## wingnut163 (Jan 3, 2013)

tjcruiser said:


> SantaFe,
> 
> I think you pegged it ... at least from my fuzzy memory ... the graphite mix ... I think that's what we had discussed here a while back.
> 
> ...


then why did the make the paint called radiator silver, i can remember reading and painting it on our radiators.

and john, black is used to capture heat in solar set ups.


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## gunrunnerjohn (Nov 10, 2010)

wingnut163 said:


> and john, black is used to capture heat in solar set ups.


Exactly what I said, read it again. 



> _*and for the other direction of heat transfer*_, solar heating arrays as well are black


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## tjcruiser (Jan 10, 2010)

wingnut163 said:


> then why did the make the paint called radiator silver ...


Looks and style, perhaps? In the end, the color doesn't affect efficiency all that much. See here ...

http://www.newton.dep.anl.gov/askasci/eng99/eng99320.htm

Lots and lots of other 'net discussions on the subject, too.

TJ


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## gunrunnerjohn (Nov 10, 2010)

From your same source...



> So black is a very good radiator precisely because it is a good absorber.


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