For licensed colorists (or an experienced home colorist working with a permanent color kit that specifies a 20-volume developer) doing standard permanent color services — full gray coverage, depositing/toning color, or modest lift. It's not a standalone product; it has no use outside being mixed into a permanent hair color.

20 volume developer is the workhorse strength for most permanent color services — strong enough to open the cuticle for full gray coverage and even color deposit, without the extra lightening power (and extra risk of dryness or damage) that comes with 30 or 40 volume. Choosing Hi-Test's cream format over a liquid developer is mainly about application control, since the thicker texture is less likely to drip or run.

Mix the amount recommended by your chosen permanent hair color product with Hi-Test Cream Peroxide 20 Volume, following that color line's specified ratio (commonly around 1:1 to 1:1.5, but always confirm against the specific color product's own instructions). Apply evenly to hair and process for the time the color manufacturer specifies, then rinse thoroughly and follow with shampoo and conditioner.

20 volume is the more moderate, everyday developer strength for permanent color services, so it's less likely than 30 or 40 volume to over-process or damage hair if processing time runs slightly long, and the thick cream texture is easier to control during application than a thin liquid peroxide. On the other hand, 20 volume provides only modest lift, so it isn't the right choice for a service that needs to noticeably lighten hair, and like any developer, it does nothing on its own and must be correctly ratioed with a compatible permanent color.