Quote Originally Posted by Photo Engineer View Post
Thanks. I'm sure everyone will enjoy this. PE
Ron or anyone else:
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).

Mark