I've been reading posts on APUG for some time now and I am absolutely fascinated by the idea of mixing up my own E-6 Chemistry. (Whether I ever will or not remains to be seen ) In various threads it is said that E-6 still requires formalin in the process. The Formulary doesn't list formalin, but a quick Google search comes up a 37% Aquarium solution called Formalin-MS, such as https://www.petsolutions.com/Default.aspx?ItemID=64000033. Can you use this stuff, or similar, as the formalin? Is this true for other things like KI, Acetic Acid (Vinegar) and so on? Some of this stuff is really expensive from chemical houses but much less costly from the "grocery store" so I was wondering. Thanks!