Wandering on the net I've stumbled across the following site http://www.a1.nl/phomepag/markerink/hieslide.htm. Very interested I saw that cupric sulphate is used instead of KMnO4 or K2Cr2O7. Is this possible, or anyone of you have tried this? Although the intended formula is for Hie film only, would it be possible to develop normal b&w negatives to obtain slides? Using Cupric Sulphate would be beneficial instead the very poisonous Potassium Dichromate or even the Potassium Permanganate. Any hints?