Does your soap look like it has weepy tears of water on it sometimes? Does it form a crystalline structure after a few days, making your soap look powdery and matte? Imagine my surprise when I found my own personal weeping Papal icon! My brother in law is a Monk for the Vatican. I’ve been planning a special soap for his next visit here. It’s all in good fun and very tongue in cheek but when it started weeping, it did make me pause. Luckily, the phenomenon is not any sort of warning from “on high” but instead, is a common soap reaction referred to as “Glycerin Dew.”
Melt and Pour soap has extra glycerin added to it during the manufacturing process. Some bases have (supposedly) up to 20% glycerin in them – that’s a lot of glycerin! The good thing about glycerin is that it is a humectant – this means that the glycerin moisturizes by drawing water into itself. The theory is that when you wash with glycerin soap is that there will be a thin layer of glycerin left behind, which will then draw moisture from the air, onto your skin (thus moisturizing your skin). That’s the selling point of glycerin soap.
When the melt and pour soap sits out on the counter, the glycerin in the soap will draw the moisture out of the air, and onto the soap. If you live in a humid environment, or have your soapmaking room near the bathroom, you’ll find that your melt and pour soap always wants to ‘sweat’ or get ‘glycerin dew.’
* Make yourself a drying container. Get an airtight container and put silica beads (silica comes in vitamins, or new shoes) into the airtight container. Then, place your soap in the container for up to 2 hours, checking on the soap every 30 minutes. This will keep your soap drier on the outside. Don’t leave the soap in the drying container too long however, or else you will find yourself with a shrunken, unattractive bar of soap because all the moisture will be sucked out of it!
* Buy a dehumidifier and use it in your soaping room. Ideally, the soaping room should be as airtight as possible for this option to work. While it is a fairly expensive way to go, it does work and it gives you the freedom to make larger batches of soap without fear of glycerin dew.
* Run a fan over the soap continually after the soap is popped out of the molds. This may not work in some more humid environments but it works in some less extreme cases so try it with some smaller batches before you go crazy with this way of dealing with soap sweat.
*The Number One Most Important Tip to Preventing Glycerin Dew? Make sure you do not put your soap in the freezer or refrigerator after making it. Let it harden in a normal, room temperature.
There are other things that could be contributing to soap sweat (boiling the soap, freezing the soap etc…) but the most common culprit is excess humidity. Good luck!