How do you use wella t18?

To use Wella T18 (Lightest Ash Blonde) toner, first, mix it with a developer, typically a 20-volume developer, in a 1:2 ratio. Apply the mixture to pre-lightened, bleached hair, focusing on areas where you want to neutralize yellow or brassy tones. Leave it on for 30-40 minutes, checking the color regularly, then rinse thoroughly and follow up with a conditioner. Always perform a strand test beforehand to ensure desired results.