Many people confuse blackheads, whiteheads, and sebaceous filaments, but understanding what is happening under the skin makes watching (and performing) extractions even more fascinating! Understanding Extractions: Blackheads vs. Whitehead Blackheads form when a pore becomes clogged with a mix of dead skin cells and natural skin oil (sebum). The top of the pore remains open to the air, causing the trapped material to oxidize and turn dark brown or black. Contrary to popular belief, blackheads are not dirt—they are simply oxidized oil! Because the pore opening is widened, gentle pressure allows the plug to slip out cleanly.