...there was no such thing as pink guards issued by Airfix.
This is not to say that you won't find them, it's not to say that I don't remember them being pink in the boxes - they were! But it is to say that I believe they left the factory gates as nice red figures, ready for a bit of matt black on the bearskin and trousers.
The early plastics - as an industrial product/by-product of the oil industry - particularly the cheaper ones, were supplied to end-users as small beads (or sheets - Bellona) of a pale, cream, clay, dirty-white or putty shade (these days some 'raw' plastics come a semi-clear or milky-glue colour), totally pigment free, the pigment was then added to the beads prior to moulding as a faintly greasy powder. I say 'cheaper' as people like Merit and Tudor Rose were producing colour-fast plastics before these figures hit the shops.
Some pigments were more colour-fast then others, and in the case of the guards (both sets - see also Guards Colour Party; next post below) the case seems to have been that the pigment was so weak that the figures went pink after a few weeks or months on the dealers shelves. This was the 1950's remember; these figures were sold in bicycle repair shops, village stores and ancient branches of Woolworth's with no air conditioning, they got very hot in the summer and quite cold in the winter (especially overnight)...indeed they might even be placed too close to a bar-heater mounted on the wall near-by! These environmental actions seems to have caused the pigment of various batches to either fade or migrate to the surface - or both.
The above (upper) shot shows from the left; a - headless - figure which has faded to the base colour (coincidently the same colour as some early Station Accessory sets), next to him is a figure that has faded to a pale pink but shows the darker residue of red in the deeper recesses of the moulding and then the figure that causes the confusion...an apparently pure, even pink-coloured figure. However the shot below to the left shows what happens if you scratch the base of one on these 'pure-pink' figures, you get the same base colour right under the surface.
I would imagine that as the plastics industry developed, the nature of the pigments changed, the 'faded' figures having a pigment that fades-out to nothing (left figure) or leaves traces of red (second left) while the 'pure-pink' figures have a pigment which while fading from red also migrated to the surface as a relatively stable pink layer (the late ethylenes from Began-Beton and some of the Matchbox figures from the mid-1970's would suffer the same problem). But they were almost certainly all red when they were made.
Further advances in the technology led to the darker vermilion-based red (the forth figure from the left) then a shiny, glossy scarlet-based red and finally the awful cream colour of the civil, Napoleonic, late Wild West and ground-crew sets.
Also shown here is a common problem with flash between the legs of the later issues.
As hinted above; it was also a bit odd for the type and mix of instruments - how many fifer/pipers? But they were toys and in the late 1950's must have been a colourful addition to the dining table on a rainy day. One also suspects they were - in part - intended for model railway layouts, where they would make a fine addition to a low relief high-street or parading outside the station for an expected dignitary on the 9.15 from Waterloo!
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