What can cause a hardened sebum?

Answer by  MattK (1713)

If a sebum is allowed to sit there for weeks at a time, rather than attempting to get rid of it earlier, the air will dry it.

Answer by  Jakecutter (1819)

This is usually caused by a blemish or blackhead much like a zit which sits in your pores and festers, hardening after a while to become sebum cists under the skin.

Answer by  Travis404607 (3916)

Sebum is a fluid produced by the sebaceous glands which are found all over the surface of the skin. Hardening of this substance can be caused by excessive sweat production, dirt, or oil from hair. When these mix with the sebum, it becomes pasty and dries, clogging the sebaceous gland and causing a cyst to occur.

Answer by  cristymyers (42)

A hardened sebum is caused by a blackhead in your pores.It is backed up puss deep down underneath the skin.