"two drops tames even the most bothersome barnet"
-- Early advertisement for Sleekeazy's Hair Potion (Pm)
Used to style hair.
History and Notes
Fleamont Potter, father of James and grandfather of Harry Potter, "quadrupled the family gold" by inventing Sleekeazy's Hair Potion (Pm). Potion-making must run in the family, since his illustrious ancestor Linfred of Stinchcombe invented the Pepperup Potion and Skele-Gro (Pm). This explains the vast pile of galleons in the Potter family vault at Gringott's bank (PS5).
References from the canon
A label for Sleekeazy's Hair Potion was included in the Harry Potter Wizard Collection label set. The label was apparently designed as a movie prop, so it's value as canon is questionable, but it reads as follows:
Hair Potion and Scalp Treatment Suitable for All Types of Hair. Unique Results for Gingers.
Ingredients: Gomas Barbardensis, Asian Dragon Hair, Petroleum Jelly