Isaac:

I have not noticed a film left behind when stripping SU-8 but normally we are
just interested in the selectivity when we do deep silicon etch. Have you tried
to do a chemical clean after using H2SO4+H2O2? What might be left is non organic
material incorporated into the SU_8 which gives it is epoxy properties. Try a
wet clean and see if it goes away. Give me a call if you want to discuss
further. Bob Henderson 480-968-8818 x11