Based on previous incidental finding (refer to this post), I had begun to put in an experiment in finding out the usability of the purified crystals. Using Lea’s Sugar Developer’s formula, it had resulted the same strength and characterististic from the original on both tests.
Though what seemed to be much interest was the appearance of ferric sulphite ‘dust’ within the two developers developed at different time-frame. And the other would be the colour of the purified crystals had yet to change anymore than ‘yellowish’ tinge, even after more than a month, compared to the original use of technical grade (99%) iron (II) suphate heptahydrate, which had turned dark tea, or ‘reddish’.
The new findings were the time frame for filtration differs, which would be advantageous for practitioners to have this mixed a day or two earlier, and would be able to take them for field work without the need for filtration.
I am sure that there’s more factors could be accounted for, or even improved as there’s many variants of formulas to try out and factors to consider such as ambient temperature, exposure to light while contained, etc.
However, new test is been conducted in keeping the developer in a light proof container, as it is one of the factor of reacted in producing ferric sulphite.
I am sharing this findings here, as well as on academia.edu (click here for the link)