Coffee Grounds for Hair Coloring

A: Yes, coffee grounds can make brown hair appear darker, but the effect is temporary. You can make almost any hair color darker with coffee. Hair that is more porous absorbs water-based pigments more readily, allowing more of the coffee's color to penetrate the hair shaft. Less porous hair will show only a subtle change.
A major drawback is that coffee grounds are not a real hair dye. Since the color simply coats the hair, you may experience issues such as color transfer onto towels, clothing, pillowcases, or upholstery when the hair is damp. In hot, humid weather or if you perspire heavily, the color will bleed or fade more quickly.
Coffee grounds themselves can also make it difficult to achieve an even result. The grounds may cling to some sections of the hair while missing others, creating an uneven appearance. For this reason, many people find that rinsing the hair with very strong brewed coffee produces a more consistent color. Some choose to leave the brewed coffee on the hair for 20 to 30 minutes before rinsing with cool water to maximize the staining effect.

While coffee can be used on almost any natural hair color, it works best when you're simply enhancing or darkening an existing shade rather than trying to create a major color change. Brown hair can appear richer and darker, dark blonde hair may take on a light brown tint, and black hair may gain a slightly warmer, shinier appearance.
Coffee cannot lighten hair, cover gray hair reliably, or replace professional hair color. Think of it as a temporary tint or color-enhancing rinse rather than a true dye. If you're looking for a subtle boost in depth and shine without using chemical color, coffee can be an inexpensive option.
©Hairfinder.com
See also:
Color your hair with fruits and berries
Natural ways to achieve highlights
How to dye your hair with henna