What is Vellum ?

[Crystaltips]

I am going through a load of SB magasines and I like the idea of printing onto vellum .... What is this please ?

Is it acetate or something different ?

Thanks

Vellum was originally a translucent or opaque material produced from calfskin that had been soaked, limed, and unhaired, and then dried at normal temperature under tension, usually on a wooden device called a stretching frame.
A modern equivalent is made out of cotton. Known as paper vellum, this material is considerably cheaper than animal vellum and can be found in most art and drafting supply stores. Usually translucent, paper vellum is often used in applications where tracing is required, such as architectural plans.