experiment first before trying a very large quantity of the spheres. It’s not recommended that they be used with dry salt as they may float on the tub and stick to the skin. Mesh size: 28/60 meaning particle sizes are 250-600 microns, this is the most popular size used by toiletrymakers. Mix several colors for a cool confetti look! Shelf Life: 2 years from date of shipping when kept in original unopened container and stored at or below 35C.; Storage: Store in cool dry place. Protect from direct sunlight. ; Recommended Usage: Jojoba Spheres may be used in formulation from 1% to 15% depending on desired visual effect and aggressiveness of exfoliation. They are 100% biodegradable.