I also used it...
yup, better to tape the holes.
There will be a fine dust that comes up when pouring, so better to do it in a big open space or out doors.
I have tried 24 hours and mostly it works good. Some here have posted about leaving the ball in for longer and getting good results. (Older balls might need the longer time). Officially ebonite says longer than 24 hours doesn't help any. (I also seem to recall, not sure tho, about reading ebonite saying very long exposure might hurt the cover.. but am not really sure.)
hope to have helped
regards
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DARK BEER IT IS THEN!