No coming off once it's dry. It's permanently one with the cape. Once acrylic dries it becomes water tight. You can actually use it on t-shirts and wash them.
With anything though if you are gonna give it a go, do it bit by bit. Add a wash, let it dry and so on.
Doin this right now
Watered down acrylics.
Half water/half paint.
Is this the precise measurement?