Maybe I can answer your question since I use the hot process to make soaps. I love castor oil and have used it extensively in my recipes, both as a superfat at the end of the cook cycle, or without the superfat and added it in the beginning. I won't ask you to put up your recipe, however, if you're using castor oil at about 10%, you're going to get some nice glide. Certainly using less than 10% is great, too, especially if you already have moisture-locking ingredients on top of that. And the glycerin content naturally made in the soap-making process should also add to the glide. Hope this helps. =)
If you want superfat in your recipe, but want that superfat content to come from the castor oil, then you can add that oil last after the cooking process. I do this with my 0% superfat recipes to control how oily they will be when they finish curing. Good luck with everything, I hope it all goes well!
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