Smokeboxes. Matt, satin or gloss?

[JZ]

Browsing through layout on here and in the press, I notice that quite a few people paint their smokeboxes matt black. Looking through old prototype photos, it appears that the same finish, certainly on black loco's, is more the norm, maybe 60-70%, where as a more matt finish to about 20-25% and on the rest it appears to be a glossier finish. Is this down to each particular works? Or perhaps what paint was in stock at the time?

 

Just interested and I don't want to start a heated debate on the matter.

[Mick Bonwick]

When newly painted they'd be gloss and would then turn matt in service. Heat and paint don't go too well together.

 

If you don't want heated debate on RMweb, don't post there.     

Edited December 16, 2017 by Mick Bonwick

[Coppercap]

Not sure what they were painted with in the works, whether it was a special paint or not, but bear in mind the boiler and firebox are covered in relatively thin cladding with a layer insulation underneath, whereas the smokebox is just a thick single skin, i.e. with no cladding or insulation, so the outside surface is going to suffer more due to the heat. Whether this makes it go matt, I dont know, but you often see rust bleeding through paint on smokeboxes.

 

Edit: ah, beaten to it!

Edited December 16, 2017 by Coppercap

[34theletterbetweenB&D]

Practise probably varied between the big four, but I have had sight of the LNER paint specification, and the finishing coats on black locomotives were the same 'Japan black' on steelwork, including boiler clothing, roof and smokebox. But on the smokebox - and fittings mounted on it such as the chimney - after preparation, filling and red oxide undercoat standard all over the loco, a coat of 'Asbestos Black' was specified in addition, before the Japan black was applied. I imagine the asbestos black was intended to help the finish 'hold' against the heating. Colour photographs of newly turned out black locos from the paint shop are uniformly the same gloss black all over.

[Killybegs]

If it's a model you are painting, go by a photo of the loco (and period) you are trying to replicate.

[kevinlms]

Browsing through layout on here and in the press, I notice that quite a few people paint their smokeboxes matt black. Looking through old prototype photos, it appears that the same finish, certainly on black loco's, is more the norm, maybe 60-70%, where as a more matt finish to about 20-25% and on the rest it appears to be a glossier finish. Is this down to each particular works? Or perhaps what paint was in stock at the time?

 

Just interested and I don't want to start a heated debate on the matter.

I was under the impression that smokeboxes got painted more often than other parts of the locomotive. Why because the paint more often was burnt due to extra heat, especially if the smoke box door had been leaking air.

[Dunsignalling]

General rule of thumb that works for me - If you have a photo of your chosen loco or another of its class in the condition you want to model, copy it.

 

Other than that:

 

• ex-works loco - gloss.

 

• working loco that is well looked after - satin

 

• high mileage/neglected/mucky loco - matt off-black (dark grey) - the pigment noticeably fades after a year or two in traffic. 

 

John

Edited December 16, 2017 by Dunsignalling

[34theletterbetweenB&D]

... the pigment noticeably fades after a year or two in traffic...

 Pigments don't fade or shift in colour (unlike dyes) they are intrinsically the colour they are. The pigment in traditional black paint is lamp black, essentially soot, which is amorphous carbon. What happens is that the paint binder and surface finish degrade, and this with the deposit of other dirt changes the perceived colour. Chip the paint off, and the inside will be as black as the day it was applied, as you are able to see the pigment with nothing else intervening.

[The Johnster]

I am by no means an expert on works' practice in paint shops, but brand new locos show the same finish on smokebox as the rest of the loco.  But smokeboxes get very hot, and this means that they need repainting between overhauls, at the shed probably during boiler washouts.  Locos in service often show the smokebox with a different finish to the rest of the loco, discernible even when the loco is quite dirty.  One sees locos with smokeboxes 'matter' than the rest of the loco, glossier, and just, well, sort of different.  

 

I have replicated this on my Hornby 42xx, weathered by myself but with the smokebox left as Hornby made it, in this case slightly shinier than the rest of the loco, and it has attracted some favourable comment from a contributor to this site whose opinion I greatly respect in such matters; yay me!