@DianaMoon -- "...Interesting contrarian take - I've always read that castor oil does add lather...."
You're right that this is the most common line of thinking, but Carolyn @cmzaha isn't being contrarian on this point; she's just being accurate. Like many other tidbits of "common soap making wisdom" this idea that castor makes or adds lather is not strictly correct.
New soap makers often design recipes that have a large % of castor in them but are otherwise rather unbalanced recipes that won't lather well with or without the castor. They have gotten the impression that castor is this amazing lather maker, and they want to know why their soap doesn't explode with bubbles.
It's best to think of castor in soap as a lather enhancer rather than a lather maker. Using a small % of castor in a soap recipe will increase the water solubility of the soap as a whole. It also increases the wall strength of the soap bubbles that form so the bubbles survive longer before they break. The net effect is the soap lathers a bit easier and the lather lasts a bit longer. But if your soap doesn't lather well to begin with, adding castor won't perform great miracles.
A soap high in lauric and myristic acids (coconut oil soap, for example) lathers well but the bubbles are weak and don't last long. You don't need castor to increase the water solubility of this type of soap, but it will help the bubbles stay bubbly longer.
A soap high in palmitic and stearic acids (lard soap, for example) doesn't lather well, but the bubbles that do form are stable and long lasting. Castor would be helpful in a soap like this to increase solubility so the lather develops more easily with less work and in cooler water.
My advice is to start with a recipe that lathers pretty well without castor, then tweak the formulation by adding a small % of castor and compare the castor and no-castor versions.
You're right that this is the most common line of thinking, but Carolyn @cmzaha isn't being contrarian on this point; she's just being accurate. Like many other tidbits of "common soap making wisdom" this idea that castor makes or adds lather is not strictly correct.
New soap makers often design recipes that have a large % of castor in them but are otherwise rather unbalanced recipes that won't lather well with or without the castor. They have gotten the impression that castor is this amazing lather maker, and they want to know why their soap doesn't explode with bubbles.
It's best to think of castor in soap as a lather enhancer rather than a lather maker. Using a small % of castor in a soap recipe will increase the water solubility of the soap as a whole. It also increases the wall strength of the soap bubbles that form so the bubbles survive longer before they break. The net effect is the soap lathers a bit easier and the lather lasts a bit longer. But if your soap doesn't lather well to begin with, adding castor won't perform great miracles.
A soap high in lauric and myristic acids (coconut oil soap, for example) lathers well but the bubbles are weak and don't last long. You don't need castor to increase the water solubility of this type of soap, but it will help the bubbles stay bubbly longer.
A soap high in palmitic and stearic acids (lard soap, for example) doesn't lather well, but the bubbles that do form are stable and long lasting. Castor would be helpful in a soap like this to increase solubility so the lather develops more easily with less work and in cooler water.
My advice is to start with a recipe that lathers pretty well without castor, then tweak the formulation by adding a small % of castor and compare the castor and no-castor versions.
