Ron or anyone else:
Originally Posted by Photo Engineer
If you decide to mix this, could you weigh the beaker, thermometer and stirring rod, both before starting and after finishing the mixing? The difference between those pre- and post-weights will be the total weight of concentrate you got. It will include the carry-out loss on the thermometer and rod, so it should be accurate. Divide that by whatever you multiplied the formula by (I suggest 3x), and you get the g/L of concentrate to use. It should be about 23 g/L. Whatever number you get, that's the number you should use when using the developer. I'm curious what number somebody else gets after careful measuring.
I just checked the accuracy of the syringe I use for measuring propylene glycol (PG), and discovered that it's just over 1% short. A more accurate weight of concentrate should be more like 23.1 g/L instead of 22.8. But for normal usage, specifying "use 23 g/L of concentrate" will be plenty accurate.
Note that the weight of raw ingredients is 23.326 g, using a sg of 1.036 for PG. With the syringe-correction, mine weighs 23.1 g. That's a loss of about 0.2 g, which should be the weight of PG and water that got steamed out. Some PG is lost through vapour, so water-loss is even less than 0.2 g. But 2.2 g of sodium metaborate 4 mol contains 0.8 g of water. That tells me little water is steamed-out. So I suspect D316 could be mixed at room-temperature, although it would take hours or perhaps days to dissolve it all. And you can forget about steaming-out water (referring to the discussion about this a few weeks ago).