Hi, I will try and give you the basics.
Majirel is a permanent colour, mixed 1:1.5 ratio so 1 tube (50ml) + 75ml 12.5 vol (3.75%), 20vol (6%) or 30vol (9%).
12.5 Volume lifts up to 1 level lighter.
20 Volume lifts up to 2 levels lighter, and is for white hair coverage.
30 Volume lifts up to 3 levels lighter.
On natural levels 1-3 you lose one level of lift (so 20 vol only lifts one level)
When working on 50% or more white hair you use 1/2 target shade + 1/2 natural basic or golden basic.
(use natural basic for cool target shades, and golden basics .03 / .3 for warm target shades)
E.g. Target shade 8.1 (cool shade) - use 1/2 8.1 + 1/2 8 + 20vol
Target shade 7.4 (warm shade) - use 1/2 7.4 + 1/2 7.3 + 20vol
Development time is 35 minutes.
Majirouge is a sub division of majirel, and is longer lasting & brighter reds. All the same rules apply as above, although some of the shades cover 100% white hair without adding any basic.
Majirel Mix are mixtones that you can mix into your majirel colour to either intensify (make brighter) or neutralise warm undercoats. When using them you do not add any extra oxidant to the mixture.
e.g. Client wants 5.6 but more red - use 1 tube (50ml) 5.6+ 1/2 tube (25ml) Majirel Mix Red + 75ml 20/30 volume developer.
Client is a natural level 3 and wants to be a 4.3 (gold). The undercoat of a level 4 is Red, which would overpower the gold target shade, so you could add Majirel Mix Green to the 4.3 neutralise the red.
For neutralising you can add up to 1/2 tube on levels 1-4, up to 1/4 tube on levels 5-7, and 1-3cm on levels 8-10.
Majirel High Lift is a high-lift tint that is mixed in a 1:2 ratio, e.g. 1 tube (50ml) + 100 ml 30 volume (9%) or 40 volume (12%) oxidant. Lifts up to 4 1/2 levels lighter. Does not cover white hair. Development time is 50 minutes.
Majicontrast is designed to give very intense red shade on dark hair without prelightening.
Mixed 1:1.5 ratio e.g. 1 tube (50ml) + 75ml 20, 30 or 40 volume oxidant. (20vol on previously coloured hair). Only suitable for off-scalp use e.g. highlights.
Development is 35 minutes or 15 minutes under heat.
Hth!