Gray hair is often resistant to perms. If you decide to try one on your gray hair, it's important to talk to your stylist about how to prepare your hair for the process, or to choose a perm that's safe for gray hair if you're applying it yourself. A perm that's strong enough to add curl or body to your hair, but gentle enough to prevent breakage or dryness, is essential. According to Sally Beauty, it's important to choose a formula that has a brightening agent so that your hair won't yellow as it's permed.
Purchase an alkaline perm that's designed for gray hair from a local beauty supply store. It'll help to give uniform curl to gray hair that's especially coarse and resistant. Or, talk to your stylist about alkaline perms available in the salon that are specially formulated for gray hair and will prevent discoloration.
Ask your stylist to perform a strand test before applying the perm to your whole head, or perform the strand test yourself if you're putting the perm in at home. It may take longer than usual for gray hair to perm, but you'll also need to make sure that the perm isn't too strong for your hair.
Apply the perm according to the instructions, or have your stylist do so. Keeping the chemicals in your hair a few minutes longer than the package directions recommend may help the perm to "take."
Make sure your hair is washed with a shampoo created for gray hair so it won't have a green or yellow tint. A shampoo with a dark-purple or violet base color will help to balance your hair color and take any unattractive tint away. The perm should be completely washed from your hair before conditioning.
Make certain that a quality conditioner is applied to your hair after perming. It'll lock in moisture and keep your gray hair from appearing brittle. Put a leave-in conditioner in your hair at least once a week as well; it'll make the hair softer, less resistant to curl and less frizzy, all problems after hair turns gray.