Living in Ohio in February is guaranteed to have everyone bundling up, and trying to find ways to stay warm. But I bet you never thought about the impact temperature has on the soapmaking process! Well, more technically, it is the soap curing process that is impacted significantly. Let me explain:
Soap making begins by combining the lye water solution with the oil blend, both held at the same temperature at the start of the blending process. Lye is both caustic, and thermodynamic – as Lye meets other ingredients there is a heat development. In fact, when lye is added to room temperature water it will sharply rise to almost boiling temperature in under 30 seconds. After the lye water has cooled down, when the lye water is added to the oil blend there will be another thermodynamic temperature spike. This is actually necessary to create the saponification process – turning the oils and water into a solid we know as soap.
Once the blending has been done, essential oils and botanical elements added, blended, and the soap mixture has been poured into a mold this is where the cold can have an impact on the completion of this saponification. The soap must be held at a warm temperature, and allowed to gently cool. (For those who are potters or glass blowers you would identify with the idea of annealing, or slowly allowing the item to cool.)
We use a pile of old bath towels, and as each batch is poured we cover the mold with freezer wrap, and then a couple large old towels. when it is excessively cold we have several old (no longer used) blankets for this also.
The molds are allowed to cool slowly – normally we allow at least 1 day, sometimes 2 days before un-molding and cutting the bars.
So what happens if it cools too quick? The soap becomes like unset jello – parts of the soap congeals and sets, and other parts are still at a consistency of pudding. The batch is basically ruined if this occurs.
So the answers:
- Insulate the molds – we use towels and old blankets, but you can also buy 1 inch foam insulation sheets, and build boxes that fit over your molds. The foam sheets have a higher r value, holding in the heat.
- Store the insulated molds in the warmest spot – we have a rack a few feet from our furnace in the basement, which is the warm spot.
- Give time for the set up.
Soapmaking is an art – there are so many variables that can affect the outcome. Knowing and anticipating those conditions helps to ensure a constant, well crafted product.