Why Does M&P Soap Sweat?
Melt and Pour Soap Bases contain high levels of vegetable glycerin. Glycerin is a natural byproduct of the saponification process. The ingredient glycerin is a humectant. A humectant is a substance that can retain and preserve moisture, therefore also preventing loss of moisture as well. Humectants are very important in bath and body products. Having a moisturizing aspect to your products is especially crucial for the dry skin type products.
Sometimes, during the manufacturing process of melt and pour soaps, extra glycerin is added. Glycerin is a key ingredient for making clear soaps. Some types of melt and pour soaps even have up to 20% of pure glycerin in them (this would be why glycerin is listed so highly on the ingredients label). But remember this glycerin is what gives melt and pour soap some of its highly sought after qualities, easy to color and mold, skin loving nature, mild and gentle soap (good for children and sensitive skinned), and very highly moisturizing naturally.
In fact, it is believed that in theory when you wash your hands with glycerin soap, there will be a thin layer of glycerin that is left behind after you rinse off the lather. This layer of glycerin then does its humectant job and pulls moisture from the air, keeping your hand moisturized until the next wash. But, it is also this same ingredient which is causing your melt and pour soap to “sweat”. Some people believe that m&p sweat is inevitable, but there are some steps you can take to help avoid and reduce sweat.
Because glycerin is a humectant, the sweat that is produced after m&p soap in unmolded is actually condensation from the air that the glycerin drew out unto itself. This is a very important element to remember if you live in an area with high heat and high humidity, or if you are soaping while it is raining outside. Humidity is the number one cause for sweat.
How to Reduce M&P Soap Sweat
One of the best suggestions that we have for reducing the amount of sweat on your soaps is to have a dehumidifier in your soaping area. You also want to keep the temperature of the room where you are soaping constant. Drastic changes in temperature will also enhance soap sweat.
The first option in reducing sweat on m&p soap, especially if you live in a very humid area, is to store unmolded soaps in an airtight container. By doing this, you are eliminating any extra moisture to be retained by the glycerin. One tip we have learned from our customers is to spread a thin layer of aroma beads into the bottom of the air tight container. Since aroma beads absorb liquid, this will also better your chances of having an air tight moisture free environment for your soaps to dry and harden.
In addition to the aroma beads, you will want to use drying racks in your containers if possible. Setting your soap directly on top of the aroma beads for long periods of time will also dry out your soaps. The time limit that the soaps can be in the air tight container is 2 hrs. The soaps should also be checked and rotated every 30 minutes.
Some soap crafters use muslin bags to lay their soap out to dry, rotating them once a day. This however will only work if you live in an area that does not have high humidity.
Although there is some debate as to when you can wrap your soap to avoid sweat, the general consensus is to wrap your soaps immediately after unmolding, if you are not storing them in an airtight container. Regardless of whether you are using, plastic wrap or saran wrap (sealed with a heat gun), or shrink wrap, the sooner you get the soaps covered, the less chance glycerin has to draw moisture to the outside of the soap.
Another way to reduce sweat forming on the soap is to allow the soap to cool and harden naturally. You want your soaps to harden at room temperature (70-72 degrees). Even though you can speed up the hardening process by placing your molds in the fridge/freezer, it should NEVER be any longer than 15-20 minutes depending on the size of your mold. Also, this step should never occur right after you poured the hot melted soap in the mold. Wait until your soap has already started to harden. The drastic temperature change from piping hot to freezing cold will lead to soap sweat. And, you never want to completely freeze soap. When the frozen soap thaws, you can almost guarantee soap sweat.
On a closing note, soap sweat does not affect any of the soap’s abilities. Soap sweat happens naturally in humid environments that the soap is in. Although using the preventative measures listed above will help to reduce the amount of soap sweat that occurs on your bars of soap, soap sweat may still appear. The humectant agents in your soap are just doing their job, collecting moisture from the air, just as it will to moisturize your skin.