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Beardie

WWI Whites were they really Persil bright?

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On 13 September 2017 at 1:20 PM, Beardie said:

That is the big issue, modern acrylics and acrylic inks as used in decal production are very white as the acrylic vehicle is clear without tint where all the previous types of paint and dope had a very noticeable tint.

 

Of the three types of white that are readily available Titanium white iis the brightest but was only commercially available from 1916 and, at that point, it was considered an 'industrial grade' as the purity wasn't very good meaning the pigment had a greyish, muddy tone to it. Lead white has a naturally warm, creamy colour to it which would have been accentuated by the oil or dope used in the paint and finally zinc, while reasonably pure white, is very transparent so has poor covering power and also does not form a strong reliable paint film prone to severe cracking and drying.

 

I think I have now clarified in my head that bright white doesn't really fit the bill. All I have to do now is figure out an appropriate way to tone down my decals

 

There were more types of white pigment available then than just the three you have mentioned, including zinc sulfide and barium sulfate (blanc fixe) to make lithopone and other compounds or co-precipitated forms. Lithopone could darken with exposure to a more greyish white depending on the proportion of zinc sulfide used. The quality of white pigment varied with opacity translating into cost and manufacturers like DuPont marketed different grades or "seals" of white. Titanium dioxide whites did not become common until after the war in the 1920s. One of the ways manufacturers overcame yellowish whites was to add very small amounts of ultramarine to their formulae, resulting in colder whites. For example a typical recipe for ordinary white enamel was 7 lbs of zinc oxide to a quarter ounce of ultramarine blue in a mix of copal, dammar and French oil varnish. Industrial documentation from that era reveals a huge range of formulae and recipes for paints and finishes of all types with colours often graded by quality (there were five commercial Venetian Reds each with its own formula, becoming cheaper as the red pigment decreased and the extender increased).

 

The pigments could be mixed by weight as dry powders, often combining pure white pigment with terra alba, gypsums or China clay to reduce cost, extend quantities and improve opacity, and then added to aeroplane dope. Or they could be manufactured in a paste form to add to the dope. Out of direct sunlight the finish would have yellowed or ambered over time just like the old modelling varnishes. The presence of sulfide in the paint can cause darkening almost to black. 

 

Even titanium dioxide varied in quality and "whiteness" dependent on manufacture and towards the end of WW2 the German titanium oxide pigment was of poor quality and yellowish hue.

 

White pigment is actually transparent and the white appearance is achieved by the difference in refractive index between pigment and medium to effect the best light scattering and reflection.

 

Nick

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interesting, Nick. what do we know about what was widely used at the time? 

 

the problem we've got right now is most 'bright' whites we've got available are titanium based, and as you say wouldn't look anything like period titanium whites. 

 

all of this strongly suggests they whites weren't super bright. 

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When I used to help white-wash farm buildings we added a handfull of copper sulphate crystals to every 10 gallons of wash; it was to keep the white white

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Indeed Nick I read you loud and clear.

 

If I am understanding you correctly you are saying that the white used could have a number of different tints but bright white is probably the least likely although it may well account for the brighter appearance of the factory painted tails and insignia.

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Here in the Cyclades, the traditional method for mixing up one's white paint to paint one's house, barn, apothiki, wall, etc, would be to mix up your white wash paint as one would, then, ahem...hmmmm...relieve oneself into the mix.  Apparently the urea has an effect on the pigment, rendering it's brightness longer lasting.  Like I said, this is traditional, but painters still do this for exterior paint.  No lie...I have seen it done.  

 

 

 

 

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54 minutes ago, Beardie said:

Indeed Nick I read you loud and clear.

 

If I am understanding you correctly you are saying that the white used could have a number of different tints but bright white is probably the least likely although it may well account for the brighter appearance of the factory painted tails and insignia.

I don't think that zinc white based paints of the time would have been any less white - or brighter for that matter - than modern 'Chinese white' watercolour paints. The snag is that the basic white pigment (mostly) went into an aeroplane dope or varnish with its associated yellowing or ambering issues. However I don't believe that would have yellowed the colour so much as to appear cream simply because in Orfordness Report E30 of February 1918 on 'Daylight Camouflage of Aeroplanes' it is mentioned that in trials in France with two  BE2cs painted in new experimental camouflage colours one of them had the white portion of the roundel overpainted in cream, presumably to tone it down. If the roundels had already appeared cream that should not have been thought necessary?

 

My "go to" source for WW1 British aircraft colours is Bruce Robertson's 1996 book (although I have Owen Thetford's 1943 book on the subject too). Mr Robertson provides typical Methuen, FS and BSi values for the various dopes in use but not for the whites VW1 and VW3 which he depicts in the book as "white" white (e.g. not cream!). The white dopes were described as Zinc Oxide but whether pure or extended for economy/opacity I couldn't say.  

 

Nick

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Ah but here we have perception again, what was considered white at the time? The colour of paper or the colour of snow (If snow is it under a grey sky or in sunlight) or the colour determined scientifically. What colour was cream at that time? Was the cream pasteurised, thick, thin what type of cow? :D Without a colourimeter it is hard to set the boundaries, then of course there is metamerism to be taken into account and the differences in the appearance of colours depending on how they are applied, the surface it is painted on, whether it is glossy and smooth or matt and the light source it is viewed in.

 

Perception plays such a huge part in these things that, like the other discussion we are back at personal taste.

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The big thing, and the question that started this debate is - Do any of the whites that 'might' have been used at the time of the Great War resemble the bright stark white of modern acrylic decals?

 

Humbrol Satin White enamel looks pretty white when it is applied, albeit with a very slight brownish caste from the linseed oil but, when a decal is placed on top of it you see a gulf between the stark white of the acrylic decal ink and the white of the enamel paint.

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