Sounds like a cellulose nitrate-coated fabric to me, certainly a popular (and less costly) leather-like upholstery cover material of that period.  There have been a number of papers published about assessment and treatment of period upholstery covers of this material, and you shouldn't have much trouble finding reference materials regarding testing.  I'm out of the office today and don't have access to my library, but you might want to contact list member Helen Alten, if you need more immediately answers.

Jane Hammond
ICA-Art Conservation
www.ica-artconservation.org
On Feb 15, 2013, at 1:04 PM, Peggy Derrick <[log in to unmask]> wrote:

> The La Crosse County Historical Society would like to reupholster the seat on its 1922 American La France fire truck and I am trying to determine what the original fabric was, and what is my best option for a correct replacement. At first I thought it was upholstered in black leather, but upon examination I realized I was looking at a heavy woven cotton with a surface treatment to make it black and waterproof. The fabric itself is not in terrible shape, but the sewing thread is rotting. Maybe we should just stitch it back together? I'm curious to know what the surface treatment is: rubber? It's not crumbling or stiff like old rubber. Paint? Ditto. Vinyl? Isn't 1922 too early for vinyl?
> Are there any simple tests I could subject a tiny bit to, to analyze it? And while I'm asking all these questions, does anyone have a recommendation on what to recover it with?
> Thank you all so much!
> 
> Peggy Derrick, Curator
> 
> La Crosse County Historical Society
> 
> P.O. 1272
> 
> La Crosse WI 54602
> 
> 608-782-1980
> 
>