Put the shea butter and safflower oil in a glass or metal bowl inside a pan filled with water on low heat so they starts melting slowly.
Once melted add the arrowroot powder and mix well.
Put in the freezer for 5 to 10 minutes until it has started to become a wax but is still soft. if it is too frozen, you won't be able to whip it.
Add essential oils and glycerin if desired.
Then take it out and start whipping with an electric mixer (like the one you would use for egg white) on low speed.
You need to ensure your shea butter and oil mix is not completely frozen. In order to whip it, the mixture must be soft and you can easily mix the shea butter and oil together. See this example in the photo.
Make sure you wear an apron and that the bowl is deep enough so the butter does not start flying around everywhere in the kitchen!
Begin whipping your mixture on low speed until it become creamy.
Once the mixture is creamy and you see strides in the body butter, it is whipped so stop right there! Do not overmix or the whip body butter will become hard.
Your butter will have a very fluffy and light consistency, like a nice whipped cream!