In this post on lotion bars, Tina asks: I'm trying to figure out if there's a general rule for tweaking the basic recipe (33/33/33/1 -beeswax/butter/oil/fragrance). You said that, for example, with cocoa butter, you'd use less beeswax. So if I use beeswax at 25%, what's the rule for altering the butter and oil? Does that now available 8% (freed up by reducing the beeswax by 8%) get split between the oil and butter equally, resulting in 25/37/37/1 ? Or does that 8% get added to the oil, resulting in 25/33/41/1 ? I'm looking for a general rule about what ingredients should be increased when the beeswax is decreased. I hope this question makes sense, I just realized it's midnight and I'm a bit sleepy! I got completely absorbed (again) by your blog this evening :)
Unfortunately, there isn't a rule about how to alter the beeswax and butter: It's all about how you want it to look and feel when it has hardened. For instance, I have found that I generally do 28% to 30% beeswax to 28% to 30% mango butter, but that's only my experience with the ingredients I get from my local suppliers. I find 33% shea butter to 33% beewax works best, but that's only if it's refined or ultra refined shea butter.
As a note, this is one of the reasons the big companies tend to use things like mineral oil. They can guarantee each batch of mineral oil will be the same every time they order it. You can't guarantee that with something like sunflower oil or mango butter.
So if you have 28% beeswax to 28% mango butter, what do we do with the left over 44%? You generally add that much in oil. So I would have a recipe that 28% mango butter, 28% beeswax, 42% liquid oil, 1% fragrance or essential oil, and 1% Vitamin E (optional). However - and you know there's always a however - if you have a mango butter that is a little softer than the last batch, you might need to add a little more beeswax. I've found that what I can do is take a bit of my batch and put it in some kind of small mold and put it into the freezer. Take it out, and see if it's the hardness and skin feel you want. If you like it, then pour it into the molds or tins or containers. If you don't, then modify it by adding more of something to make it harder or softer.
So the short answer to your question, Tina, is that there isn't a general rule about how to modify your lotion bars, except that the left over amount can be added in liquid oils. Keep really great records when you're modifying these recipes so you can make that awesome thing again!
Newbie Tuesday: Let's make lotion bars!
If you want to learn more about lotion bars, here are a few post ideas...
Back to basics: The basic recipe
Back to basics: Lotion bars - tweaking the waxes
Back to basics: Lotion bars - tweaking the butters and oils
Back to basics: Lotion bars - let's get complicated
Back to basics: Lotion bars - wrap up and link-o-rama
The chemistry of our nails: Lotion bar with lecithin and lanolin