This is a photo of some stock that I made about two weeks ago. I made it using a Korean method
. This was boiled for a few hours. It is not greasy and the milky color comes from the minerals leached out of the bones. I then cooked some noodles in it and it was great.
To make stock this way take your bones and soak them in cold water for one hour. Drain the water and replace with cold water. Soak for one more hour drain.
Add water again and place on high heat. When it starts to boil start timming. After 20 to 30 minutes
pour out water and wash the bones. What you have done is removed the blood from the bones. Now put the bones back on high heat with clean watter and boil for several hours. As your water level goes down add more just keep the bones covered. You will see foam and grease come to the top just keep skimming that off and throw it away.
I have two vids that show me using this meathod.