Fixative has now been sprayed onto the piece. I put on 3 layers. As you can see, there has been some loss of material/media. Pastels powder and the force from the spray scatters it. The force is not strong and after time when the piece is moved around, it will lose that light layer anyway. It is a good idea to "blow" some of those layers off first. The bottom layers are what is now showing through. The fixative tends to darken the media as well. Mostly what is lost is the lighter values or the white. This problem is associated mostly with chalk pastels and not other drawing or paining media. If this was pencil, there would be very little noticeable difference if any. More layers of pastels will be added. 24 hours is usually need to give the fixative sufficient time to dry. Next step is more pastels, mostly white.