A final followup on the original experiment. The caked, dark DPD powder that was used in the original test was now a hard chunky lump that had to be ground up. Yesterday did a 25 ml sample test of that vs. good powder and the results were the same at FC=1.0 Today, after bringing up the FC, both measurements were 3.6 So.....looks like the DPD powder is pretty stable even though it looks pretty bad. I certainly don't recommend letting the powder get this bad but some dark gray discoleration should be nothing to worry about.
Al
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