A question of colour

Model and prototype rolling stock, locos, multiple units etc.
tmcsean
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A question of colour

Postby tmcsean » Sun Feb 02, 2020 8:21 pm

In many colour photos of working BR steam locomotives, there is a distinct reddish tinge to the black shades. While working out a paint mix to replicate this I found myself wondering whether the photographs were recording the result of 1950s paint technology degrading from the heat of the metal, or was it perhaps some defect of the emulsion used on some types of colour film?

I've googled this and am no better informed. Does anyone on the forum know?

Tony McSeán

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Noel
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Re: A question of colour

Postby Noel » Sun Feb 02, 2020 10:08 pm

BR steam locos [apart from the ones in red, green or one of several shades of blue] were officially "Blackberry black" and were definitely just black. Variations could be introduced by the film processing. The amount of rust and dirt on the loco could also affect the result. Colour films of the era did vary, and some photographers used slides rather than prints, so the stability of the result was somewhat variable; early Ektachrome slide colours, for example, deteriorated very quickly. Dufay prints from the late 1930s to early 1950s, which used a different technology to some other colour films, could have a colour cast, although not always red, from the few I have seen.

Perhaps you could show us one or two, or give us links , so we can see what you are concerned about?
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Noel

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Jol Wilkinson
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Re: A question of colour

Postby Jol Wilkinson » Mon Feb 03, 2020 5:18 pm

Blackberry Black was the description given to LNWR locomotive black. According the the LNWR Liveries book, it was simply "drop black", with several coats of varnish. The blackberry hue is thought to be a result of cleaning and final polishing with oily rags.

Phoenix Precision Paint's LNWR Blackberry Black has distinct purple tint. Whether or not this is based upon an actual paint sample I don't know.

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Noel
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Re: A question of colour

Postby Noel » Mon Feb 03, 2020 5:33 pm

R A Riddles was on record as intending the BR lined black livery to replicate the LNWR livery; I may have conflated two things wrongly, as, on checking, BR black was apparently just called "gloss black". It would probably not have had such a high standard of finish as the LNWR black.
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Noel

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Tim V
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Re: A question of colour

Postby Tim V » Mon Feb 03, 2020 5:37 pm

In the pictures I have, freshly painted black engines are definitely black. Engines in use exhibit a brownish tinge (as do coach underframes), I put it down to brake dust dirt etc.

So I think you need to brush up (!) on your weathering skills ...
Tim V
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bécasse
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Re: A question of colour

Postby bécasse » Mon Feb 03, 2020 9:50 pm

Tim V wrote:In the pictures I have, freshly painted black engines are definitely black. Engines in use exhibit a brownish tinge (as do coach underframes), I put it down to brake dust dirt etc.

So I think you need to brush up (!) on your weathering skills ...


Using a red rather than grey primer for BR black locos can help to produce that elusive brown tinge although weathering will still be required.

It is perhaps worth noting that the initial specification for the new mid-60s BR corporate livery required coach underframes and bogies to be finished in a matt brown rather than black.

tmcsean
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Re: A question of colour

Postby tmcsean » Tue Feb 04, 2020 11:02 am

Google image comes up short when you are looking for hard-worked BR locos, but I have two colour albums - BR steam in colour and British Railways seam in colour which include many engines that show a red-brown tinge. In his book Martyn Welch recommends including Humbrol 62 (a matte, fairly pale brown) in the blend. I don't usually advocate looking at pictures of locos to work out what to do. But in MW's case I think we are on safe ground, and his online galleries at http://www.martynwelch.com show a red to brown cast in most of the "black" locos.

I've no doubt that BR engines started their lives with a glorious rich black coat, but they didn't stay that way for very long. If you look at a lot of colour photos of working engines, there is a huge range of colour shades in evidence. Many of them, like Mack the Knife, with not a trace of red - which got me wondering if it was real life or dodgy colour film at work. Bit of both, probably.

Tony

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Noel
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Re: A question of colour

Postby Noel » Tue Feb 04, 2020 2:46 pm

tmcsean wrote: I have two colour albums - BR steam in colour and British Railways seam in colour which include many engines that show a red-brown tinge


I have BR Steam in Colour 1948-1968 [I assume that the other book has a different title?] and would refer you to the top photo on page 35. Apart from possible rust, the brownish-red colouration has to be external, most likely brake dust, as this is a green loco, as is the Grange on page 41, although in both cases the green has darkened. Perhaps even more interesting is the G2A on page 44. which shows a number of different colours, including some relatively clean plain black, again supporting the suggestion that the other areas are just dirty [note that red buffer beam…] although it's rust on the wheels and sandpipe and probably the smokebox [which is not insulated, unlike the firebox and boiler barrel]. I think Tim is probably right about the weathering, although the starting point may need to be a very, very dark grey, rather than pure black. What the photos show to me is that, base colour excepted, there is a variety of shades even on one loco.
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Noel

SteamAle
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Re: A question of colour

Postby SteamAle » Sun Feb 09, 2020 10:49 pm

What is really needed is a chemist who knows how to make a black paint!
When I worked in a factory, in another life, we dyed man made materials black but, there is always a but, there was no such thing as a black dye. We had to mix different colours to make black and one of the main ones was red.
No doubt a physicist could tell us about light and how we get black and white light, which is a similar problem!
So - does anybody now how they make black paint and what does it contain?
Philip

DavidM
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Re: A question of colour

Postby DavidM » Mon Feb 10, 2020 3:28 am

Here’s a start:
https://m.wikihow.com/Make-Black

Maybe a demo at Scaleforum, just needs a few tubes of acrylic - and a willing 4 year old.

David

tmcsean
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Re: A question of colour

Postby tmcsean » Mon Feb 10, 2020 9:54 am

SteamAle wrote:What is really needed is a chemist who knows how to make a black paint!
When I worked in a factory, in another life, we dyed man made materials black but, there is always a but, there was no such thing as a black dye. We had to mix different colours to make black and one of the main ones was red.
No doubt a physicist could tell us about light and how we get black and white light, which is a similar problem!
So - does anybody now how they make black paint and what does it contain?
Philip


This is a common problem, because to colours that look the same can be made from different consitutents. This can occasionally produce startling results when you're trying to wear or fade the basic colour. I once tried to fade the BR crimson on a couple of MR non-corridor coaches. They were painted in RailMatch crimson and I mixed in some Humbrol 64, which is a nice lazy way for achieving fade. I ended up with a couple of coaches in a very fetching pale purple. I had to do a complete repaint using Precision's crimson, and H64 worked its usual magic without a problem. After all the trouble, I found that Precision do an excellent premixed faded BR crimson.

The only time I ever use "proper" black is a spray of shiny acrylic base coat to provide a secure key for the lettering, crests and lining. Even for a very clean engine, I prefer to take into account the effects of scale on the perception of colour by lightening the corporate style manual colours rather than risk ending up with something that looks more toylike than a Hornby figure.

Tony

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Guy Rixon
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Re: A question of colour

Postby Guy Rixon » Mon Feb 10, 2020 10:08 am

SteamAle wrote:What is really needed is a chemist who knows how to make a black paint!
When I worked in a factory, in another life, we dyed man made materials black but, there is always a but, there was no such thing as a black dye. We had to mix different colours to make black and one of the main ones was red.
No doubt a physicist could tell us about light and how we get black and white light, which is a similar problem!
So - does anybody now how they make black paint and what does it contain?
Philip

I don't know what goes into modern paint, but traditional black pigments were lamp black, which is made from soot, and bone (or ivory) black, which is made from burnt bone (or posh soot). The lamp black was much cheaper. Artists' ranges still contain "ivory black". It can't be made from actual elephants, and I don't know if it's really bone black or something brewed to give the same spectral response.

When physicists call something black, they mean that it absorbs or emits equally at all wavelengths. It's possible that the red dye in the mix for black dye was there to remove the shorter, bluer wavelengths. However, bear in mind that the colour of a mundane thing is typically the colour of the light that it scatters or reflects. At room temperature, a thing may absorb visible light, but it emits thermally only in the far infrared.

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Noel
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Re: A question of colour

Postby Noel » Mon Feb 10, 2020 11:19 am

I don't have any information about locomotives specifically, but coaches and wagons in the 1930s were painted with oil based mixtures, some of which which included "black in oil", the exact proportions depending on what it was applied to. Wagon sheets were coated in a mixture which included "vegetable black" as the colourant, also known as carbon black, so I would think that the oil in black was likely to be the same material in an oil base, although lamp black and animal black [aka bone or ivory black] are other possibilities. Various qualities of materials were available, but all were based on carbon, albeit from different sources, and could fade to grey over time. The one exception was bituminous paint, a mixture of bitumen and white spirit, used for the interiors of some wagons.

Given that this was the basic paint technology in use during the steam era, it seems a reasonable assumption that engines would also have used it, with the final outcome dependent on the quality of the materials used, the colour of the undercoat and the number of layers of varnish. Any slight blue tint arising from the carbon black would possibly be cancelled out by the brown tint likely from the oil base and the varnish [blue + brown in this context = black, again].

Dyes are a very different form of technology, and since the 1870s have commercially been petro-chemical based. The methods used to create colours are not comparable with paint, so far as I know.
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Noel

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Guy Rixon
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Re: A question of colour

Postby Guy Rixon » Mon Feb 10, 2020 1:57 pm

Concerning dyes, yes they're different to paint pigment, notably in that they are soluble. However, a "lake" paint is made by precipitating soluble dye into insoluble particles of pigment. For example, Alizarin, an organic dye, plus alum yields madder lake.

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LesGros
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Re: A question of colour

Postby LesGros » Mon Feb 10, 2020 5:15 pm

Perhaps an Artistic member, such as Martin Goodall, would like to comment on the effect that ambient light has on colour percception.

At Scaleforum, the change from pre-exhibition glim lighting to ready-to-view illumination of Burntisland, for example, was most instructive.
LesG

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never made anything useful

martin goodall
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Re: A question of colour

Postby martin goodall » Tue Feb 11, 2020 5:32 pm

LesGros wrote:Perhaps an Artistic member, such as Martin Goodall, would like to comment on the effect that ambient light has on colour percception.

At Scaleforum, the change from pre-exhibition glim lighting to ready-to-view illumination of Burntisland, for example, was most instructive.


I was tempted to add my tuppenceworth to this discussion, but then I let it go, until Les Gros tempted me to join in after all.

Leaving aside the variability in colour perception between different people, colours are affected not only by atmospheric conditions (such as smog – which was very prevalent in London up to the late 1950s, even on a fine day), but also by the effects of weather generally, as well as time of day, angle and strength of sunlight falling on the object, etc, etc, etc. As a general rule, colours tend to be lighter and more subdued the further the objects in question are from the viewer, and there is also a ‘blue shift’ in the spectrum the further away an object is from the viewer; i.e. colours tend to go towards the blue end of the spectrum. Thus green trees on the distant horizon may actually appear to be blue. This is a phenomenon well-known to artists, who often aim to reproduce this effect (known as ‘aerial perspective’ or ‘perspective-in-colour’), in order to create a sense of depth in their paintings.

We can do the same on our models, not only by the use of colour but also by reducing surface texture and details the further back on the layout the feature in question is located. This is, in fact, contrary to the oft-repeated mantra that everything on the layout should be built to the same standard. I fundamentally disagree with that proposition. The only models on my layout that are really highly detailed are those nearest the front of the baseboard (such as the Station Building and Train Shed, seen in S4 News No.214 and 215). It would be a waste of time incorporating a similar level of detail in models standing further back on the layout.

I have applied this technique to the buildings on the layout. Those backing on to the backscene, are built of plain styrene sheet with no texture at all, and doors and windows are simply pencilled onto the surface of the walls. This was a deliberate artistic decision, and you may or may not think that it ‘works’, but it’s what I intended. Buildings standing further forward have textured stone walls (Wills scenic sheet), which have been weathered with soot, and so on. Roofs (both limestone and Welsh slate) are noticeably lighter at the back of the layout than those standing nearer the front of the layout. Here is a photograph of the layout that I took a few days ago, in an attempt to illustrate this point. The effect is fairly subtle, so you may be forgiven for not really noticing the difference.

IMG_5815 (2).JPG

However, this brings us back to the original question, which was focused on the ‘correct’ rendition of the livery of locomotives and other railway vehicles. I am quite convinced that there is no such thing, and that any attempt to capture the exact shade of paint applied to a particular locomotive in the paint shop of the Great Smashem Railway on the first Monday of June 1905 is doomed to failure, even if you are aiming to reproduce the engine’s ex-works condition. As for the colour of railway vehicles that have been in service for more than a few months, there are so many factors affecting the perceived appearance of the colour of those vehicles that the subject denies any objective analysis. What, for example, represents the ‘correct’ rendition of BR bauxite as applied to vacuum-fitted wagons? A glance through a few colour albums should convince you that this is an impossible question to answer, and so we can only attempt an ‘artist’s impression’ of the appearance of these wagons in their many and various conditions, even (in fact especially) when seen together in the same train.

Going back to the photo of my layout shown above, all those roofs covered with Welsh slate are, of course, ‘slate colour’ but, for the reason I explained above, I have painted them in different shades of grey to show the colour receding the further back they stand on the layout. The slate is also represented by different materials, depending on how far away it is from the front of the baseboard.

I haven’t even started on the issue of soot deposited from above on rolling stock or mud and dust thrown up from below. But I think I’ll leave it there. The general message is – Stop worrying about ‘correct’ colours, and concentrate instead on colours that look ‘right’ to you in the context in which they are intended to be viewed.

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LesGros
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Re: A question of colour

Postby LesGros » Tue Feb 11, 2020 6:00 pm

Martin,
:thumb
LesG

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SteamAle
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Re: A question of colour

Postby SteamAle » Thu Feb 20, 2020 6:14 pm

Martin
Many thanks for your wonderful response. Furness red has always been a bone of contention and I've always said it depended on what day of the week the paint was mixed as to the end colour.
You've given an excellent answer and your model is very good as well.
Do you do commissions?
Philip

martin goodall
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Re: A question of colour

Postby martin goodall » Sat Feb 22, 2020 1:34 pm

SteamAle wrote:Martin
Many thanks for your wonderful response. Furness red has always been a bone of contention and I've always said it depended on what day of the week the paint was mixed as to the end colour.
You've given an excellent answer and your model is very good as well.
Do you do commissions?
Philip


Sorry for the slight delay in replying to this.

Regrettably, I don't undertake commissions. (I haven't even got enough time to do as much as I would like to progress my own model-making!)

However, I did explain the methods I used to paint the backscene on my layout in a two-part article in MRJ 220 and 221. As I explained there, it's actually easier than you might think, and I recommended doing one or two practice pieces in order to gain experience and confidence before embarking on an actual backscene.

I haven't written any articles yet on the construction of buildings for the layout (although I have touched on this subject in my Burford Branch thread on this forum). Both the paints used (artist's acylics) and the techniques and choice of colours have employed the same approach as I used when painting the backscene. My intention was that the buildings, particularly towards the back of the layout, should in effect be a 3D extension of the backscene.


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