I thought I could stay out of this fray, but I have to say this: I did not ever publish a formula for fixer, and if I had it would not have contained borax. You did not respond to my questioning the probability of significant potassium content in technical grade borax. The refinement of raw borax ore by the producers of 20 Mule Team products involves, as you might expect, solution in hot water and crystallization. Although there may be potassium remaining as a soluble impurity among the 1300 ppm maximum allowed in technical grade, it is difficult to see how that fraction of the small amount of borax used in any of the formulae I have seen could have a drastic effect on fixation, except in the psycholigical sense. Even so, it can easily be reduced by a factor of 50 or so in the home laboratory simply by making a saturated solution of the technical grade with at least double the amount needed for saturation, discarding the clear liquid, and making another saturated solution with the sediment from the first. If the solutions are saturated at high temperature, the last solution upon cooling will produce crystals of very pure borax decahydrate. How much did it cost to do this with borax that costs 50 cents a pound at the local supermarket? These are procedures that require little attention.
Flashpoint is the temperature at which an open flame close to the surface of a liquid will ignite the liquid. I tested that with the propylene glycol. It ignited as predicted, but there was no explosion, an open flame was required for ignition, and the burning glycol was easily extinguished.