Vishwanath Somashekar wrote: > b) NaOH (0.3mol/litre) mixed with a littel DI water and then Ethanol snip... > On the NaOH side of the channel, after > running the solutions for about an hour or so, I see black deposits on > the PDMS. I am not a chemist, but to me it sounds, as if the NaOH reacts with the PDMS and sets carbon free. Check the chemical stability. Marc