Can it be done? The utility room where I keep mine is bone dry and it lives on a worktop well clear of the floor so the only thing I can think of doing is taping one of those little silica gel sachets into the lid. I don't have any though...
must be something to do with the particular brand and the container once its seal is broken. just buy one of the clip-loc boxes from the supermarket and ditch the original packaging the powder comes in...