My pillow cover cleaning

My pillow cover cleaning. Was scrubbing for a while before I took this video. Tough stain. Was a lot worse. Was hard to see clearly [the stained part itself I mean] in the previous video I think because of the window bright light. I did one take then shut the blinds and moved it over some, help, but still not as clear an image as I would have liked to have had. Pretty amazing how the outer black silk pillow case that goes over it, the protector, and the pillow that my head used to be on, and will again after today, testing time, sustained no discoloration or texture change at all. That stuff they use must dry fast, uhh,uhhh I mean , wow, my head sweat dander must have passed through the pillow molecules and left them unscathed. Sarcasm. I have one real silk cover, this one on this pillow and a cheaper synthetic one on the other. The synthetic one feels more satiny.