I mixed: 40g water 25g potassium dichromate 500g concentrated sulfuric acid http://books.google.com/books?id=Fl57Byhp0ecC&lpg=PA114&ots=wYk-A7i9px&dq=delrin%20etch%20chemical&pg=PA114#v=onepage&q=delrin%20etch%20chemical&f=false I guess this mixture is commonly called chromic acid. Things that I should have done: Use a Pyrex beaker Don't use the magnetic stirrer, just use a teflon stir stick Use an ice bath at the beginning of the procedure