Blond hair can be dyed darker by properly prepping the hair to sustain the new color. The darker shade should ideally be within three shades of one's natural hair color.
- Deep condition the hair
Treat the tresses with a deep conditioning treatment at least a week before coloring the hair. This helps the dye to take to the hair well and prevents streaking. It is best not to shampoo the hair a day or two before dying it. The natural oils in the hair help to protect the tresses during the dying process.
- Treat the hairline, and mist the hair
Rub petroleum jelly along the hairline, and spray the ends of the hair with water just before dying it. This keeps the dye from getting on the skin and prevents the ends of the hair from soaking up too much color.
- Apply the dye
Divide the hair into four sections, and secure the sections with a hair clip to keep them from meeting. Apply the dark color to the hair one section at a time, from root to tip. Wait three days before shampooing the hair. This provides the hair cuticles with ample time to seal in the color molecules from the dye.