After my post about finding olive pomace a tricky soaping oil, I've had a couple of emails asking about my fragrance oil testing recipe. I used to use a recipe consisting of equal parts coconut, olive, and palm, but since giving up palm oil completely, I've developed an effective recipe which contains equal parts:
Olive Oil -- gives a good indication if the fragrance will seize
Coconut Oil -- lets me know if the fragrance oil will compromise lather
Rice Bran Oil -- contains palmitic acid and lets me know if the fragrance will stick in the finished soap
Avocado Oil -- I wish I could claim a specific reason. I use this oil because I love it. :)
While it's impossible to know how a fragrance oil will behave in every soap recipe, I find this simple four-oil soap gives a pretty good indication. It also makes an excellent bar of soap!