The Sharpie brand of permanent markers comes in an assortment of colors, one of which matches most hair colors. The process of using markers on hair is one way to do quick touch ups and cover up gray hairs, though widespread use is not always in the best interest of your hair's health.
Gray Coverage
Using a Sharpie marker to cover up some rogue strands of gray hair is similar to coloring hair with semi-permanent markers. One caveat of using Sharpie markers is that the permanent ink will not wash out, nor will it fade over time. This means that coloring hair with a Sharpie will result in a streak of color that will remain. One additional effect of the Sharpie on hair is damage caused to the hair, as the hair underneath the marker will dry out and potentially break off.
Root Cover Ups
When hair has been colored and begins to grow out, the roots closest to the scalp tend to be a different shade compared to the rest of the hair. If you use a Sharpie marker as a solution to color hair roots, you run the risk of getting the permanent marker on your scalp. If you get the marker on your skin, you will have a difficult time removing the ink. In addition, the scrubbing and process involved with removing permanent ink will weaken hair close to the area you will be trying to treat.
Wig Highlights
One way to use a Sharpie marker for hair, without any negative consequences, is to use the markers to create highlight on wigs. Whether the wigs are made of synthetic or human hair, you can create streaks of color with a Sharpie. Though no negative impact will be incurred, you should use caution when using Sharpies for this purpose and ensure the highlighted areas are completely dry before handling the wig to prevent staining of the skin.
Facial and Body Hair
The same manner in which hair on the head is lightened, darkened, dyed and highlighted can also be used for hair on the rest of the body. If you use a Sharpie marker for coloring in bald patches of a beard, covering random gray eyebrow hairs or even darkening mustache hair, you run the risk of weakening the hair follicles. Hair needs to be free and clear of oils and pore-clogging particles to allow for continued hair growth and nourishment. By using a Sharpie, and getting too close to the root bulb of the hair, you risk stunting hair growth or causing damage to the hair over time, since it will not grow properly or receive nutrients supplied through the hair follicle.