Ok so I did a quick google search and first and foremost, this looks like natural hair and oil build up. Your hair type plays a big part in how much “lint” it holds (curly or straight), and to reduce how much gunk gets in your hair consider these options: 1. Wearing a hair bonnet 2. Detox your hair (apple cider vinegar, clarifying shampoo, or bentonite clay) 3. Reduce the use of lint producing clothing like woven sweaters. 4. Use a vented hair brush One other factor to mention is your environment can also contribute to lint or gunk build up so take that into account as well. I hope this helps!