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Hiya 

I would like peoples thoughts on roof colours do you model them white  or do you model them grey , why do you model  them in that  colour

Daz

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Depends if you want a factory fresh vehicle - GWR white roofs quickly turned to grey due to grime and oxidation of the lead pigment.

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I use grey but vary it between vehicles, as different times out of the shops and different environments would have meant that they were not uniform. A useful way of using up those oddments of grey paint, especially if like me you are modelling pre-grouping.

Jonathan

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Never pure white (apart from when freshly painted) but a slightly weathered white and every shade of dirty grey in between that and absolutely filthy.

 

7 hours ago, dpgibbons said:

Depends if you want a factory fresh vehicle - GWR white roofs quickly turned to grey due to grime and oxidation of the lead pigment.

 

This is a very misleading statement, how quick is "quickly"?  I've seen some people (not saying you) suggest a matter of days without any evidence at all! There is plenty of photographic evidence to show that "white" roofs were a lot more numerous than people keeping repeating the same old memes that you would never see them in service. Here's an Example of Taunton from Britain From Above website:

WhiteRoofsDontExist.jpg.063eea8b74eb19af38c6ad4644743894.jpg

 

Not every roof would be white, but then not every single one would be grey/black either. The key is variety. Also don't forget, that lead white is not a pure white colour, it's an off white to start with.

 

 

 

 

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I model 1948 so any white roofs (stopped in WWII?) would be quite weathered by then.  I have some stock with bright white roofs painted before I knew better.  When upgrading, I weather or use grey but try and vary it a bit.  There are photos on the forum of coach roofs where the white is weathered very differently at one end to the other (eg autocoaches that always had the loco at the inner end).

 

Will

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This gets discussed fairly regularly on RMWeb & elsewhere & I remember it being observed that whereas white van roofs appeared in greater numbers than many assume it does seem that white carriage roofs were much rarer - they seemed to discolour quicker. It was suggested that carriages spent a greater percentage of their lives actually running behind steam locos & so were subject to more loco exhaust than vans which spent a lot of their lives idle in goods yards. An interesting theory.

 

Martin

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3 hours ago, WillCav said:

I model 1948 so any white roofs (stopped in WWII?) would be quite weathered by then.  I have some stock with bright white roofs painted before I knew better.  When upgrading, I weather or use grey but try and vary it a bit.  There are photos on the forum of coach roofs where the white is weathered very differently at one end to the other (eg autocoaches that always had the loco at the inner end).

 

 

Good point about post-war GWR, my comments are more related to pre-WWII. Having said that I have a 1950 pic that shows a small sprinkling of very light roofs on a train of vans still, so not totally unfeasible.

 

I posted a pic of the railmotor at Didicot showing just that sort of weather on it's roof, heavier at the engine end, very little at the far end. Also check out the clerestory coach at the front of the train in 1929. Surprisingly clean compared with the others! As Martin said, from the pics I have collected, they do seem a lot rarer on coaches though, not totally absent.

 

Westbury1929-2.png.6c58a57f156051f5a5377b7d48b8edd9.png

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I reckon that the "everything was dirty and rusty" is a bit of a misnomer.

 

Look at the colour photos in this book and see all the dirty engines, carriages and wagons. Very few of them, even in the background.

 

https://www.amazon.co.uk/Big-Four-Colour-1935-50/dp/0906899621

 

Even the cover shows a very presentable red Jubilee and train post war. ISTR the photo is dated 1949 but nearly all the stock is still in pre war livery and cleanish.

 

 

 

Jason

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2 hours ago, Steamport Southport said:

I reckon that the "everything was dirty and rusty" is a bit of a misnomer.

 

That has definitely become one of the modelling memes floating about.

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I have had many interesting conversations with friends who have considerable coach research. I get told off as, although  the white roof discoloured very quickly, a black roof is a stoning offence. Key express sets would be cleaned on a regular basis, including the roof, but other sets the outside, including the roof was not cleaned as often.

 

My Torbay Express has all clean white roofs as Old Oak cleaned the set that morning. A have a few others and my Hornby non corridor set is still as bought....but not for long.

 

My roof sections tend to be grey. I spray them with Holts Rover Tempest Grey. For non express vehicles, I tend to give an additional blow over with a quick pass of white and a final quick waft of black, to add some hint it was once white. ( it's all in the wrist action!)

 

Clerestories do look good with  a two tone roof. For the white section I prime with Holts grey and put a light coat of white with the grey showing through. Now I have too many clerestories, not long out of the paint shop, but it is my trainset!

 

Mike Wiltshire

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White carriage (or wagon) roofs had very little to do with frequency of cleaning but everything to do with the quality of air in the areas where they worked (notably the concentration of H2S) and how recently they had been repainted.

 

The white paint used was a white lead-based paint and as such subject to chemical conversion of the white lead oxide component to very dark grey lead sulphide. How quickly this happened would have depended on air quality, gas woks  were notable producers of low atmospheric concentrations of hydrogen sulphide (hence the typical gas works smell) but so was much marshland, so vehicles used only on country branches could be as susceptible to darkening roofs as those based in urban areas. The darkening of roofs had little to do with soot, except perhaps close to the chimney on rail motors, as rain would wash most soot off when it fell.

 

It seems likely that there was also a white lead component in the cream paint used on GWR carriage panels and it was this that caused those same panels to darken over time as a result of the same chemical process, inhibited to some extent in this case by the varnish coating.

Edited by bécasse
"lead sulphide" corrected to "hydrogen sulphide"
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6 hours ago, bécasse said:

How quickly this happened would have depended on air quality, gas woks  were notable producers of low atmospheric concentrations of lead sulphide (hence the typical gas works smell)

 

Presuming you meant hydrogen sulphide there. ;)

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4 hours ago, 57xx said:

 

Presuming you meant hydrogen sulphide there. ;)

Yes, sorry. I will amend the original post!

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All this discussion of the reaction of lead oxide mystifies me. According to Wikipedia white lead is a complex mixture principally composed of lead carbonate.

My GCSE level understanding of chemistry is as follows:

Hydrogen sulphide gas is I believe relatively unreactive (and the sulphur is less reactive than oxygen so would not displace it from lead oxide anyway) and would disperse quickly in the atmosphere. In the atmosphere hydrogen sulphide would dissolve in water droplets forming sulphuric acid (acid rain). This would react with lead carbonates to form carbon dioxide, water and lead sulphAtes, which are also white, but possibly importantly are soluble.

 

With regard to the role of carbon (soot). Carbon is more reactive than lead so would displace it producing carbon dioxide and lead metal, (this applies to lead oxide too) which is of course grey. At atmospheric temperatures however this would be a very slow process. However none of this takes into account any effect of the oils used in the paint formulation to inhibit or alter these reactions.  We need a paints chemistry specialist for that.

 

The soot in the atmosphere would be composed of very fine particles (microscopic) which, much like weathering powders, would adhere to any non-glossy  or oily surface and would not easily wash off (think of buildings in the industrial heartlands). It is often hard now to appreciate just how much soot there was. A lecturer at Leeds uni. once told me that in the 60s a sheet of white paper left by an open window would turn grey by the end of the day.

 

So the suggestion that coach roofs were more subjected to soot from being behind a locomotive seems a reasonable one.

 

Just as an aside my Dad always swore that the old lead white gloss he used to paint window frames with had far better colour fastness than modern lead free paints.

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