It is obvious this taste comes from metal contaminants. While he and everyone else uses 99.8% Iodine which is 0.2% metal contaminants that give it a harsh taste (and who knows what else we don't notice) I use 99.99% Iodine so the harsh taste doesn't need to be removed with magnets, it is never present in the first place. Just a heads up, I sell the purest and best Lugol'sIodine anywhere on earth...and for the cheapest price anywhere too! Just like Trappers "magnet attached" iodine, there is no harsh taste. And its only $7! I have sold over a hundred on ebay and made my own store now. Check it out!
One usually trusts the supplier. What test would you recommend that can pinpoint 0.19% difference? Taste I think is the best test. Not that it tastes like candy but the harshness is noticeably missing. Iron-y harshness.