Query regarding the use of the term Aniline Ink on stamps.

[Malaya]

Does anyone know if alizarin was used on postage stamps? Alizarin has a similar pinkish/reddish/purplish colour and also fluoresces orange.

[Global Admin]

Does anyone know if alizarin was used on postage stamps? Alizarin has a similar pinkish/reddish/purplish colour and also fluoresces orange.

Have never seen that term before personally.

[faro]

The short answer re. alizarin inks is "yes".

e.g. https://hendonstamps.com/wp-content/uploads/2021/06/THE%20VARNISH%20INKS.pdf

THE HISTORY OF THE “SO CALLED”
VARNISH INK STAMPS OF GB GEORGE V
by
Trevor I. Harris A.I.E.P.

<clip>

During KG V’s reign, many red pigments used in printing inks were formulated on
aniline-based or coal-tar extract-based dyestuffs. Some of these dyestuffs may
change colour, or take on a deeper hue, and even become a little more “rubbery” in
texture when subjected to heat (e.g., towards 95°C).

Also, one of the dyes used in the red inks of George V was alizarin crimson. This
was made from a coal-tar extract (anthracene). The process of manufacturing
alizarin had been invented in Germany in 1868.

If the ink is heated above 200 degrees Fahrenheit (95 centigrade) in an oven, it
becomes orange, and eventually extremely bright red!

These same dyestuffs may produce similar effects when treated with other
chemicals, more particularly with formaldehyde, formalin, phosgene (coal tar gas)
and microscopic elements contained in burning wood gases.

An example of this kind of chemical reaction may be found when intense (or
deeper) orange vermillion shades of the KG V Royal Cypher 1d stamp were
“manufactured” by unscrupulous people the 1920’s by treating stamps with
phosgene or coal tar gas.

The accompanying change towards a more rubbery, plastic looking appearance
when carried out under pressure (e.g. within ‘crystalline’ mounts in a heavy book)
could give rise to a more shiny and polished finish. In other words, the result could
be varnished ink stamps.

Varnished ink stamps are reported to have been found in the old 1960s style stock
books with acetate strips where the stamps had not been moved for many years. It
is therefore not at all surprising to learn that these same strips contained
formaldehyde type chemicals, the use of which has since been discontinued. This
could well be considered to be the “natural” way of producing varnished ink stamps,
although they might also been subject to heat at some period in the past.

Likewise, the same could be said for varnished ink items that occasionally appeared
in the 1950’s and later in stock-books with plastic strips which had survived despite
having been very close to a major fire, for example during The Blitz in World War
Two. The books might then have been carefully tucked away for many years, only
to re-appear at a later date containing varnish ink stamps.

However, these occasional and rare sources of “naturally produced” varnished ink
stamps cannot in any way account for the relatively large number of varnish ink
stamps now being sold in the philatelic marketplace, and we can only conclude that
they must have been produced intentionally from the 1970s onwards.

</clip>