How identifie a blood feather

I wouldn't go pinching feathers on a chicken, it actually hurts them if the feather has blood in them and can also damage the feather. You can pretty much tell by looking at the base of the feather. Feathers in the same area of the bird tend to be around the same size. So say you stretch a wing and see a feather that is drastically different in length, look at the bottom, you will see easily they are plumb and almost softer to the touch, I am talking about the stem base itself. If the feather is fully grown, then it looks lighter and drier by nature. If you observe very closely you can tell the difference even on black feathers, the width and texture of the base stem of a growing feather is very different than an established feather (older feather). Hope it helps.