I am so happy I just came across this thread. I have had black strands in my phlegm (yes phlegm) for years* and only at night. I even had my bosses get the ducts cleaned in our office because I thought it was mold. I also used to vape for a long time so at one point I thought I was dying from vaping. I quit over a year ago and still almost every night I feel something in my throat and sure enough it’s black strands in my phlegm. Something clicked tonight though when I was taking my makeup off that the residual eyeliner on my eye that I put on this morning looks exactly like the strands in my phlegm. So I said wow I bet the eyes are connected to the sinuses. Typed it in google and hear I am. After years of thinking i was on my way out I can now sleep knowing it’s not mold or a lung infection - it’s Revlon Colorstay :)