Why are my bath salts fizzing or clumping in the jar?
Short answer
They've been exposed to moisture. Make and store them completely dry.
Explanation
Use completely dry tools, mix the dry base quickly to limit exposure to humidity, and air-dry the finished salts 4–8 hours before potting. Store airtight, away from the bathroom; a silica gel sachet helps. The recipe's fizz comes from baking soda and citric acid, which react as soon as they meet water.
What to do
- Use 100–150 g per bath.
Source: The Big Book of Homemade Skin Care — Effervescent Aromatic Bath Salt