Schwarzkopf's new Oil Developer is a conditioning, caring peroxide that's optimised to work with new IGORA ROYAL but which can also be used with old-style IGORA if you still have some tubes to use up.

It comes in 4 strengths: 3% (10 vol), 6% (20 vol), 9% (30 vol) and 12% (40 vol). Use them as follows:

3% for darker or pastel colouring and for covering 100% white hair;
6% for tone-on-tone colouring, white hair coverage and lightening 1–2 levels;
9% for lifting 2–3 levels (3–4 levels with the Special Blondes), colouring with -00 shades and white hair coverage with the Absolutes;
12% for lifting up to 5 levels and for colouring with the Fashion Lights.