Please Note: Developer is not included with this product, it needs to be purchased separately.nBlue black is a shade of black with a soft blue shimmer which adds additional depth and shine and creates mind-blowing blue black styles.nA shade of black, that lends a bluish shimmer to every hair. Mixable with all 8 RefectoCil tints. Smudge- and waterproof. Lasts 6 weeks.nFor professional use only. Wear suitable gloves. Please read the enclosed leaflet before applying.nAllergy test: We recommend an allergy test (patch test) before the first application as well as after long periods without tinting.nMix RefectoCil hair dye with some drops of RefectoCil Oxidant 3% (NOT INCLUDED) until you get a creamy paste. Apply this paste without delay using the applicator. After the application time (see detailed instructions inside) cleanse with cotton and water. Remove color spots on the skin with RefectoCil Tint Remover.