Quote Originally Posted by albada View Post
I'm suspicious because the pH in the patent is 8.20, but the latest and prior XTOL-batches I've purchased measured 8.29 and 8.26 with a calibrated meter. That makes me suspect the metabisulfite was reduced and/or metaborate was boosted.
You might not be as far out as you think, the patent for XTOL lists the final pH as 8.20+/-0.05 which takes into account all the variations in the ingredients and the mixing process they considered at the time. You have done very well to get so close and it may not make any practical difference to the grain, sharpness or the characteristic curve.