Welcome back, Cor!
Originally Posted by Cor
Yes, I tried Instant Mytol a while ago. But I noticed some problems with it:
* Using TEA from Photographer's Formulary (85% pure), the pH was too high. In fact, I mixed Instant Mytol three times, but the high pH produced negatives that were too dense and grainy. Using a 99%-pure TEA available elsewhere might have helped. But the problem remains: TEA is different depending on where people buy it.
* It oxidizes quickly. Here's what mine looked like after two months:
* It uses 50 ml of concentrate per litre (1+19 dilution). I wanted higher concentration.
* As you point out, its viscosity is high (it's thick), making it hard to pour and measure.
While experimenting with concentrates, I made two discoveries:
1. Sodium metaborate dissolves in propylene glycol. Normally, inorganic salts don't dissolve in organic solvents, but sodium metaborate is an exception.
2. Ascorbic acid is easier to dissolve in propylene glycol if you have dissolved some sodium metaborate in it first. The metaborate helps the ascorbic acid to dissolve faster.
So I've been researching concentrates that take advantage of these two discoveries. The concentrate that Alan quoted above is my best so far that uses Phenidone. It only uses propylene glycol as the solvent, so it's easy to pour and will not suffer the inconsistency of TEA. It is diluted 1+49 (use only 20 ml per litre), and my tests so far show that it matches XTOL. This type of formula looks promising, which I call SMAP -- Sulfite/Metaborate/Ascorbic/Phenidone.