Tracing tracing cloth.

[Hover Fly]

Draughtsmen/women and architects of a certain age will know the stuff I mean, cotton cloth treated for drawing with ink. Any chance of finding some anywhere, or even any somewhere? Google just throws up something dress makers use, which is totally different.

 

[slowmotion]

It's a bit of a long shot, but The Insitute of Conservation might point you in the right direction.
http://www.icon.org.uk/