I made bar soap today. I'd rendered suet before and froze it. I've not done it for a long while, so I re-skimmed all my soap books to refresh my memory. I've not bought soap since we like my homemade soap, having made and used it for twenty years now.
You want the lye mixture and oil mixture to be about the same temperature around 95-98 degrees. I had to set the lye mixture outside to cool down. I put some cold water in the sink to cool the fats down some too, once the lye was down and ready. If the lye cools too much, sometimes just stirring it will raise the temp a bit. Whether I've got water in the sink or nor, I put the pan in the sink for slowly pouring the lye mixture in. You want the lye water to pour slowly like a pencil width, stirring the fat continually at the same time, using a rubber spatula. Gently keep stirring for the lye and fats to chemically connect and do their thickening thing.
Keep stirring in circles and swirls gently for at least 10 minutes. Then you can occasionally stir it. This time it set up fast (some times it could be an hour), thickened enough that when dripped from the spatula it leaves a trace on the surface, leaving a trail a short bit. At this point is when additives like scent and coloring is added. I usually don't add these, liking the creamy color and tallow or palm oil are forever sweet smelling. If lard were used, or a poor quality beef fat, it develops an off smell over time, so scenting masks this. It's best to use essential oils. Colorants I've used are things like cinnamon, cocoa, turmuric - this time in one of the soaps I added 5 tsp paprika.
See my earlier post on other soapmaking I do. And I'll be posting later, finishing up the process and thoughts.