In my experience, those wafer cassetts are sometimes made of polypropylene.
You could verify this by doing some FTIR/raman on a sample if you have
access to the equipment, or just call your vendor and ask them.  I wouldn't
use them for processing, though.

Good luck,

Brian Stahl

On Feb 11, 2011 1:49 PM, "Nikhil Sheth"  wrote:
> Hi,
>
> I bought few SOI wafers from UltraSil. They have come in one white colored
> cassette like a wafer holder with slots. I am wondering if that wafer holder
> is Teflon coated or acid resistant. Can anyone tell me how to identify
> that?
>
> Thank you,
>
> Nikhil Sheth