It is a repetition of data published by ANSI.
Originally Posted by Photo Engineer
Many, many beginners in many places have used my developers made mostly from things you can get at the grocery or hardware or country general store using common measuring spoons and have been inspired to continue photography. I made most of my photographs of musicians using homebrew without benefit of anything more accurate than a cheap spring kitchen scale.
You still haven't tried to find out if there was a reason why I could not find your reference to potassuim in fixer in my copy of Mees and James, nor explained why you should expect to find significant amounts of any potassium compound in any grade of borax. Nor have you told us what brand and grade will meet your specs and how you know it. Potassium compounds are among the first to be separated in the processing of raw borax. They are among the easiest to reduce to undetectable amounts in the purification of borax.