Q&A: De-ionized or de-mineralized water? Substitutions for liquid surfactants for oily hair? Corn starch in Neal’s Yard Products?

I’m working my way through the August Q&A now, but it’s hard to answer in short paragraphs when I see all the wonderful things you’re asking that send me off down rabbit holes! In the August Q&A, Melanie asked, I used to be able to buy distilled water easily, now it is almost impossible where I…