Many thanks, you've really brought me up to speed. I didn't mean that the film is crude, but it seems to have an 'atmosphere' that I am interested in. I know that they are used by professionals for checking light/exposure etc.
I bought my SX70 camera for peanuts in some charity shop, it's great but not what I am after. There is an artist called Lucas Samaras who does very interesting things with SX70, moulding the print, pushing the emulsion etc.
So my next question Polaroid 10x8? Can see the backs on their site but which camera will it work with?