Found it! (salicylic acid)

Judy Seigel (jseigel@panix.com)
Fri, 13 Jun 1997 21:45:06 -0400 (EDT)

With clue from Alain's forward of Bas's June 2 '96 posting I found the
following in my file:

On May 29, '96, under subject line "Buying Gum Arabic" Martin Becka wrote
(& I summarize):

LP Clerc says 2-3 g salicylic acid to 1000 cc mixed gum (500g gum, add
water to make 1000 cc)

H Schneeberger says 5 g salicylic to 1000 cc gum

Puyo says use fresh mixed gum

I [Martin] add 3 g salicylic acid to mix of 500g gum, water to make 1000
cc....

PS. Seems to me [Judy] the 50& solution makes a VERY thick gum, at least
with contemporary powdered gum arabic.....

Anyway, thanks to all.... More to follow on my search for the slowest gum
in the west....

Judy