I'm not sure what you're thinking of when you say "most/best". Everyone has a different idea of that -- as you can already see, the answers range across the board.
Big fluffy bubbles? Then the Gent and Shunt are correct -- coconut, palm kernel, and babassu are top recommendations.
Dense creamy suds? Then Susie has it -- lard, tallow, palm do that.
A generous layer of dense lather topped by a spray of fluffy bubbles? Then a modest amount of fluffy bubble fats and a generous dose of dense creamy fats will do the trick. I could never use my good beer in soap! lol.
Regardless of what lather you prefer, the others who suggest castor and sugar as lather enhancers all have a point. Oh, and beer enhances lather too.
I have once added milk and honey to a soap and I tested it with another soap that had the exact same recipe but without the milk & honey additives. The first soap seemed to making lather slower and with more effort than the second one.I've only been adding milks for a couple of weeks, although obsessively, it is so much fun, and they seem to vary w/r/t lather. CM seems best, heavy cream the worst, the others (GM, yogurt, buttermilk) in between. I don't have a very big sample size, obviously.
Sorry, I just saw this. I like 30% OO, 35% Palm/Lard, 12% CO, 10% PKO, 8% Shea, 5% Castor then use Buttermilk for half my water amount and add the BM to my oils before the lye mixture. I also use silk and SL. I like the thick creamy lather I get with it. You can use BM in any recipe though. I have a several that I've used it in and it's great in all of them.V, I agree on SL (also EDTA) boosting lather a bit. I've only been adding milks for a couple of weeks, although obsessively, it is so much fun, and they seem to vary w/r/t lather. CM seems best, heavy cream the worst, the others (GM, yogurt, buttermilk) in between. I don't have a very big sample size, obviously.
Speaking of buttermilk, does anyone have a good starter recipe for a buttermilk soap (ahem, Shunt)? I know people like them, but mine was kind of a fail. I'm pretty sure it was my fault, did not watch for overheating.
not_ally,Shunt probably adds buttermilk that's brought to room temp. It's just my guess as cold BM might probably end up re solidifying all the solid oils and butters.Thanks, Shunt, I will try the buttermilk again today! I was really disappointed w/my fail after reading about how much you and others love it in soap, but it was my fault for not watching it. Will keep a watchful eye this time. I am looking forward to trying your recipe, it looks good.
ETA, you just add the BM to the oils as liquid (ie, no supplementing w/ the powdered) and as-is from the fridge, right?