Nail primer is a specific type of manicure product applied to natural unpolished fingernails prior to applying colored polish or artificial nails. Primer for nail polish ensures that the polish can be applied evenly without streaking, and it can also help this kind of basic manicure last longer without the polish chipping or fading. Acrylic nail primer applied to prepped nails helps the fake nails adhere firmly to the natural nails. A quality primer is particularly important for artificial nails because it safeguards against the acrylics loosening or lifting. Moisture can easily become trapped under loose artificial nails and can lead to a fungal nail infection.

Most standard nail primers come in liquid form and are brushed onto the surface of each nail in a similar manner to nail polish. Some types of nail primer are made from acidic chemicals that can frequently irritate surrounding skin, so many nail technicians first apply an adhesive protector on each of the client's fingers to prevent this problem. Nail primer is normally applied after the cuticles are softened and exfoliated. Some manicurists prefer to roughen the surface of each nail with an emery board to remove the natural oils, though others caution that this step can sometimes increase the chance of nail irritation. Since acid-based primers act as dehydrating products, only one applied coat is usually enough to be effective.

Similar types of nail primer can usually be applied to acrylic nail tips with either an acrylic or gel nail overlay. Gel nails need to cure under an ultraviolet (UV) lamp, so some gel nail kits may come with primer designed to help minimize the shrinkage that happens with this type of manicure. An important step in this type of manicure is to only apply the acrylic tips and overlay once the primer has completely dried. Most brands of nail primer turn white in appearance once dry.

Acidic nail primer is normally used to help the bonding of acrylic nails to the natural nail. Most nail technicians performing basic manicures without fake nail applications prefer to use a milder non-acid primer that does not carry the risk of skin irritation. This type of nail primer is often a clear liquid that is brushed on in one to two coats before being left to dry for about five minutes. A common beginning manicurist mistake is to apply colored polish to nails with primer that is not completely dry, which can lead to an uneven finished look.