Interesting work. Thank you for the effort and for sharing the results.

I am curious about the concoction with 10x borax. Why would this result in increased contrast? I would not have expected this. Does the pH increase that much with the additional Borax? I would have thought (I am no chemist) that after a point additional Borax would have very little effect on pH.

Does the addition of the 20grams of Boric acid bring the initial pH back to around 9.25?

I have many questions about the purification process too...but...it seems completely un-necessary to me? Perhaps to you too? Would the stuff straight from the 20 Mule team box not work just as well?

Perhaps, a direct comparison of the purified to the non-purified is in order? Or, even, between reagent grade and straight 20 Mule Team?

Thanks again for publishing.