Hi, new posting here but have spent LOTS of time learning. I saw your post about adding shea butter to the NG multi-use cream base. I went to NG's site to order some and noticed they recommend only adding 2% extras. My question is: how do you know when you can add more stuff to the bases and when not. Do you just test and wait to see how long it lasts or just test to see if the emulsion holds together. Please help give me some direction. I'd like my stuff to have close to a years shelf life. Do you add more preservative? Also, is your cream light and fluffy - I'm looking for a good base to be able to make a mousse or souffle type cream. thanks