Oral use - cannabutter residue

[pseudonym0]

swim tried making some cannabutter last night. used the water+butter method with 7.9 grams of pretty nice outdoor buds and a little more than a stick of butter. let it simmer for about 2 and a half hours then strained out the cannabis and put it in the fridge to let the butter separate from the dirty water and harden. today he was perplexed about the best way to harvest the cannabutter from the top of the dirty water. ended up just prying it out with a knife which worked pretty good, but it left a small amount of butter in the water and also the bottom of the very green butter was covered with a white residue where it was in contact with the water. he's pretty sure this isn't a big deal but was a little disappointed he didn't come out with a perfect block of nice green cannabutter. anyone have experience with this method and know a way to avoid this or know it's impossible to avoid and doesn't really matter??