The stain from 130 is due to glycin, which changes over time, i.e., fresh tan glycin gives little stain,
mocha-colored semi-oxidized, some stain, old chocolate glycin an overall tea-like stain. My own
custom is to have one bottle of glycin power "aged" like a fine wine to a mid-state, and another
bottle virgin uponpened in the freezer. In other words, fresher glycin= cooler image / older, more
oxidized glycin = warmer and more stain. And we can also tinker with the formula toward cooler
by substituting benzotriozole for the KBr restrainer, at about 1/4 the gram wt, though that is not
related to staining per se.