Pat - Did does Rio Tinto Technical Grade Powder really say "none" for the insoluble particles? That surprises me as there should be a limit of some sort - i.e a value given in parts per million. As an analytical chemist, I can say that there is always going to be a little of something in most everything... unless you are talking about homeopathic medicine. Did it really say None detected or something, and that is based on the method of analysis, but really doesn't mean that there is "none". Just that that test can't detect any.
Originally Posted by gainer
The AR grade assay had absolutely nothing to do with a "known hydration". Infact, I doubt the hydration was even tested for. It was an "assay", a measurement of the material of interest.