Welcome back to another Sunday Soap Ingredient post! Today I’ll be talking about castor seed oil, a really great oil that adds much to handmade soap. This oil really should be in every soapmaker’s ingredient box since it is such a great additive.
Castor seed oil comes from, you guessed it, the castor plant. The castor plant is in the family Euphorbiaceae, which also includes the well known holiday poinsettia. The plant is indigenous to the Mediterranean, Eastern Africa and India, but is found widely around the world. The seeds are rich in a toxic protein known as ricin, which denatures during the castor oil manufacturing process when the oil is heated. This means the castor seed oil made from the castor seeds is safe and nontoxic.
So why is castor seed oil so great? Not only is castor seed oil rich in fatty acids that are great for your skin, but it acts as a humectant in body care products like soap, lotion and lip balm—drawing moisture to skin and keeping it there. It provides a ton of glide and softness to products, even when added in small amounts. A little castor seed oil will go a long way.
The oil is thick and rich, which makes it especially versatile for the liquid phase of products that need some thickening (like sugar scrubs!). It is also unique in its ability to be used as an emulsifier.
Castor seed oil is a special favorite in soapmaking due to its extraordinary ability to increase lather and bubbles. I recommend around 5% castor oil in soap recipes for this purpose. As I mentioned before, only a little is required to achieve the results you want! It’s definitely one of my favorite oils, and if you’re thinking of making soap at all I would consider this a must.