About 8 to 24 hours. It takes about 8 hours for a sponge with a thickness of 1/4 inch to freeze completely, 1/2 hour for a sponge with a thickness of 1 inch and 24 hours for a sponge with a thickness of1inch. During the freezing process, care should be taken not to freeze the sponge for too long, otherwise the sponge will become hard and cannot be used normally. Coke sponge is a soft and delicate sponge material, which can be used to make various household items, such as pillows, gloves, bath towels and so on.