Survey of India silk maps
Heliozincographed is a dead giveaway for Survey
of India maps.
Currently, eleven sheets are known, with variants. These sheets were
printed on silk. These maps do not have an edge treatment to retard
fraying. These sheets are usually a light gray or dark grey. If there is
any color, only blue and sometimes red was used.
RAAF (Royal Australian Air Force) Maps
These sheets are printed on Silk. There are twenty-seven
different RAAF silk
maps known. They are always printed single sided. These maps do not have
an edge treatment to retard fraying.
Black is the predominate color of these maps.