Temporary tattoos
Temporary tattoos are a type of body sticker, like a decal. They are generally applied to the skin using water to transfer the design to the surface of the skin. Temporary tattoos are easily removed with soap and water or oil-based creams, and are intended to last a few days.

Other forms of temporary "tattoos" are henna tattoos, also known as Mehndi, and the marks made by the stains of silver nitrate on the skin when exposed to ultraviolet light. Both methods, silver nitrate and henna, can take up to two weeks to fade from the skin.

Dyes and pigments
Placing the colour names on a colour wheel helps the artist visualize the palette. For the tattooing, a wide range of dyes and pigments can be used; from inorganic materials like titanium dioxide and iron oxides to carbon black, azo dyes, and acridine, quinoline, phthalocyanine and naphthol derivates.

Iron oxide pigments are used in greater extent in cosmetic tattooing.

In a survey, many pigments were found to be used among professional tattooists:

Substances not approved for cosmetic use: Pigment Orange 36, Pigment Yellow 74, Pigment Red 170, Pigment Yellow 97, Pigment Red 146, Pigment Brown 25, Pigment Red 266
Allowed for cosmetics with only temporary contact with skin: Pigment Violet 23, Pigment Red 122
Allowed in all cosmetics that do not come in contact with mucous membranes: Pigment Yellow 1, Pigment Orange 43
Allowed in all cosmetics except those used around the eyes: Pigment Green 7
Allowed in all cosmetics: Pigment White 6 (titanium dioxide), Pigment Blue 15, Pigment Black 7 (carbon black), Pigment Brown 6 (iron oxide), Pigment Red 101 (iron(III) oxide), Jernoxid (iron(II) oxide), Pigment Yellow 42 (iron oxide-hydroxide), Sudan Red, Food Yellow 13 (Quinoline Yellow WS), Mangan Violet (manganese ammonium pyrophosphate), Food Red 17 (Allura Red AC), Food Blue 2 (Brilliant Blue FCF), Acid Red 87 (Eosin Y)
Recently, a blacklight-reactive tattoo ink using PMMA microcapsules has surfaced. The technical name is BIOMETRIX System-1000, and is marketed under the name "Chameleon Tattoo Ink". This ink is reportedly quite safe for use, and claims to be FDA approved for use on wildlife that may enter the food supply.

Tattoo removal
Tattoos can be wholly or partially removed by cosmetic surgical techniques, most commonly through the use of lasers. The laser reacts with the ink in the tattoo, and breaks it down. After this, the patient's body then absorbs the broken-down ink and the skin heals once more. The procedure can be expensive, and very painful (some say more so than the original tattoo) and often requires many repeated visits to remove a small tattoo. It also may not be entirely effective in leaving unblemished skin, due to the fact that tattoos also scar the skin to varying degrees, depending on how the tattoo was applied, the way the skin healed, and the area that was tattooed.

Overall, green-based ink is the most difficult to remove. Black ink is most readily broken down by the laser, and unprofessional tattoos done at home are the easiest ones to remove, due to the low quality of ink used, as well as the ineffective manner in which they were applied. Before the advent of laser removal, tattoos could be (at least partially) removed by (1) loading hydrogen peroxide into a tattoo machine and then retracing the tattoo with the chemical (2) dermabrasion (3) surgically cutting the tattoo out of the skin. However, this method often resulted in a scar that was just as unsightly as the original tattoo.