Use salt instead of sand. Sand is difficult to dye. I was a dinner the
other night and the sister of the hostess had made the most delightful center
pieces by using food color and regular table salt that she had purchased from
the local dollar store. She poured the sand in mason jars and decorated the
lids with silk flowers. Sand is silica so it is very difficult to color. The
salt is porus, so color is beautifully absorbed into it.