If you have been creating Melt and Pour soaps for a while now, you may have noticed that sometimes your soap will look like its “sweating” or has a ”dew” forming on its surface. These dewy droplets appear on glycerine soap, and occasionally Cold Process Soap. This is simply a cosmetic effect on the surface of your soaps and its still completely fine to use, and doesn’t effect any of the soap’s abilities however, it doesn’t look very appealing, so lets talk about how we can avoid this where possible.
Why does it happen? Two things are required – a high humectant content which is present in some melt and pour and glycerine bases and readily absorbs moisture from its surroundings, and a moist atmosphere (which is pretty normal in New Zealand’s muggy weather). The moisture in the atmosphere is being absorbed towards your soaps, it’s not the soap moisture from the soap itself.
Differences in soap bases: Some soap bases are much less susceptible to dew. Generally Cold Process Soap doesn’t tend to sweat, but it can occur during wet seasons. Glycerine, and other humectants draw moisture towards them, so on the surface of this soap, this moisture materializes in beads that are slightly greasy feeling.
How to avoid your soap sweating:
1: Try to avoid overheating your soap when you are melting it.
2: Allow the soap to cool and set naturally at room temperature, rather than putting the soap in the freezer to unmould.
3: Store unmoulded soaps in an airtight container. You can even introduce uncooked rice or silica gel packs to help absorb some of the moisture. Or introduce the use of a dehumidifier in your soaping area. Reducing humidity is the key to preventing soap sweat.
4: Wrap your Melt and Pour Soap immediately after unmoulding, its best to use plastic wrap or saran wrap (sealed with a heat gun), or shrink wrap.
5: If your soap does sweat, it is fine to use, just wipe it away with paper towel, or blunt knife. Or just let the soap dry out a bit, but it will have a texture on the surface left over from the glycerin dew.