I too have occasionally found that CS will turn black after a few days
and have found another potential cause. Sediment left in the bottle
from earlier batches will cause newer batches to turn black. It is too
hard for most of us to detect because we're storing the CS in dark
bottles. I've found an answer to that. First, store the CS in clear
glass bottles. Wrap aluminum foil around the outside of the bottle.
That will make it light proof. When preparing to make a new batch of
CS, rinse the bottle thoroughly with distilled water (NOT TAP WATER).
Shake and pour out. If the water comes out gray or black, repeat until
the rinse water is clear. If the rinse water does not return clear,
remove the foil and examine the bottle. It may need extensive cleaning.
Just remember to use only distilled water for the cleaning. Then replace
the foil around the bottle if it has been reused.
In the last batch of CS I made I noticed that there were a few
specks of black but that the CS was clear. When I poured out the CS
into another container and rinsed out the original bottle, the rinse
water was black. It had to be cleaned twice. So it seems that the
bottles need to be periodically cleaned.
Mike
