Hello,
You can find about this exhibit in Exploratorium's Cookbook I, page
43-1. It is called Horse's Tail. It is said in the construction
instructions that a graduated material called Letraset(TM) Pantone(R)
Color Paper, graduated, uncoated, 404U-G, can be be used.
Hope this helps.
Ali Parsa
Director
Zirakzadeh Science Foundation
Tehran, Iran
email: [log in to unmask] Tel: +98 21 878-9270
Fax: +98 21 646-2613