I'm starting to dabble in bath and body and I'm confused as to what items need preservatives added and which do not. I bought the foaming bath butter base from RE and added sweet almond oil to make a cream soap. Does an item like this need a preservative? The base includes salt, phenoxyethanol, and tetrasodium EDTA...which from what I'm reading seems like they all are sort of preservatives? I also have ingredients on the way to make my own body butter. Do body butters need preservatives? The recipe I am planning on using does not involve water. Just butters, oils, and tapioca powder. TIA