Quote Originally Posted by Alan Johnson View Post
Is it needed to multiply the weight of metaborate by 1.354 (see post 85) if 8-mol metaborate is supplied?
Is there an approximate multiplier of Xtol time for development?
Hello Alan,

This developer is the same as your D316, except that the metaborate is 2.0 g/L instead of 2.2 g/L. The slightly lower pH means the times will need to be lengthened a bit from D316. For TMY2, the multiplier is 2.19, but that assumes it's formulated as a concentrate. The PG in a concentrate slows development a little, hence a slightly longer time.

And yes, I assumed the use of metaborate 4-mol (dihydrate), so 8-mol will need more.

BTW, if you want to use D316, you can add 40 g/L of sulfite instead of 45, and that will give similar results and the same times as above. I tested 40 g/L with D316, and the grain matches XTOL. This new brew has a hint finer grain, but I suspect most folks would not consider the improvement to be significant.

Yesterday, I tested 50 g/L of sulfite and dropping the metaborate to 1.8 g/L to keep pH unchanged. My preliminary results give an XTOL time-ratio of 2.15, slightly finer grain, and slightly lower true speed (1/5 stop speed-loss). The appearance of the grain is also more attractive due to fewer worms, so this is a promising brew.

Mark