Suitable capacitor dialectrics

["Garth van Sittert" <garth-at-mediasupplies.co.za> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hi All
 
I have searched the archives and couldn't seem to locate any posts that list a
set of suitable capacitor dialectrics that can be used in the primary
capacitor.  It may be useful if anyone knows of a couple to list it.  So far I
know of polypropylene, polyethylene.  Vinyl (PVC) is a no no.  Learned from
experience.  Got a 42nF 10kV homemade vinyl cap though.
 
Are polyester caps suitable for MMC's?  And what is an EMMC?
 
Many thanks
Garth (From the bottom of Africa).