©Lin Yangchen

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After the war, more than four million stamps in Kuala Lumpur remained untouched by the Japanese. They were overprinted locally with BMA MALAYA under the supervision of Captain H. Holland (Cockburn 1998), who is thought to have experienced teething problems with inks (Pollard 2000a, Cockburn 2016b). The mixing of inks was an 'imprecise art' in those days (Fernbank 2013). Thus were born the mutated shades of magenta and orange (Holley 2016) amidst the radioactive fallout of World War II.

The issued form (Cockburn 2016b) of the magenta overprint (centre), flanked by a blood-red overprint on chalky paper (left) and a lighter scarlet on substitute paper with the key plate in a slightly lighter shade than the duty plate (right). Norris (2016a) examined this copy of the magenta overprint and considers it a fine specimen.

The magenta overprint (upper row) in daylight (left) and 365 nm long-wave ultraviolet radiation (right), showing the 'volcanic lava' fluorescence characteristic of aniline-based inks (Lin 2017a). In the lower row is the red overprint under the same experimental treatment showing no signal. Rodgers (2017) subsequently reported similar fluorescence and patchiness of ink in his copy of the magenta overprint.

Fluorescence spectrum (raw data) of the magenta overprint on excitation with a 325 nm helium-cadmium ultraviolet laser (5.16 μW) through a 40× fused silica-calcium fluoride microscope objective. The signal has a main peak coinciding with that of a highly fluorescent shade of the Selangor coconut definitive 10 cents magenta, but the fluorescence of the former is even stronger, perhaps because of higher pigment purity or concentration. The magenta overprint also has an additional peak absent from the Selangor stamp, indicating the presence of a constituent not found in the latter.

Yet another variation on red was the "metallic" overprint reported on some examples of the 50 cents. The author believes that this happens when the overprinting ink is a strong red that deposits readily onto the green paper but gets repelled by the black ink of the stamp design either chemically or by the raised surface of the ink. These tiny printing heterogeneities appear as a sheen to the naked eye, accentuated by the darkness of the green paper.

Energy-dispersive X-ray spectroscopy indicates that the red overprint is composed of red lead. Barium has relatively strong peaks in the metallic overprint; this may be why the ink is so bright. This could have been done to make the overprint more prominent, as the green paper and black ink of the 50 cents make it a particularly dark stamp.

The X-ray spectrum from the magenta overprint seems to show paper coating and little else. This could mean an organic dye such as mauveine or alizarin, the latter of which can take on a pinkish shade depending on the mordant used. Both these pigments emit orange fluorescence on exposure to ultraviolet radiation; so does the magenta overprint as shown earlier. Aluminium sulphate—whose elements appear to be present—could have been used to fix pigment to paper as was commonly done.

Backscattered electron images from a scanning electron microscope, showing the presence of heavy metal in a red overprint (left) and the absence of heavy metal in a magenta overprint (right).

Literature on the magenta overprint has so far described the shade, reported specific examples encountered by collectors and postulated teething problems with ink (Holley 2016). This study makes forays into chemistry for the first time. It reinforces the idea that postal authorities may have been using a different pigment altogether, one with which a true shade of red seemed very difficult if not impossible to obtain. Was lead oxide not available, and why? Could they have sourced the organic dye from the textile industry as a stopgap? Chemical analysis helps generate further historical and cultural questions.

A partially buried strip of 1-cent stamps on the back of a reused envelope.


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