If you must use a flannel backing, line it with a sheet or prewashed muslin. This way the flannel backing will not wear/weaken from whatever you are using for your weight. Also, you truly won’t need to make that blanket that heavy. I don’t know how you would feed that blanket through your machine.
Look up proper instructions to make these weighted blankets. What are you planning on using for your weight?
As I make many of these blankets, I would suggest poly beads for the weights. Your blanket would be able to be washed in the tub and set outside to dry in the sun.
Good Luck with this project.
Last edited by Chris G; 06-13-2018 at 06:14 AM.
Reason: Additional info