Creating Foaming Bath Salts! from Point of Interest. If you have made bath salts before you know how simple it is to make. Now if you want to make bath salts (or another bath product) foam, you will need to add a surfactant to make it foam. If you use a liquiod it will cause the salts to dissolve so a powdered surfactant like SLSa (sodium lauryl sulfocectate) will be needed.