I make soap with coconut milk too. I have used the canned milk and the powder. When I get canned milk I try to find one that doesn't have any additives in it like guar gum. It's not always easy to find just plain coconut milk. I've used some with the additives and I didn't have any problems, but I've heard there could be, not sure just what kind of a problem. And when you have milk with additives you need to list them on your ingredient list. It does make nice soap.