Hey there! Great question!
Think "filler" when you are going 2 or more levels darker, or when you lack vibrancy and durability. The "filler" replaces the natural warm neutral tones that allow the new shade to pigment to couple with. Apply to clean hair a thin layer of the filler tone for what level target you desire. Your system pre pigmentation system should be mixed 2 parts water to 1 part of your pre pig. Comb through to help the spread of product then apply your new target color directly over top and process. When working on shear blonds which need a bit of tone, try a mixture mixed 3 parts water to 1 part pre pig. The 3 tones of Gold, Kopper and Red Pre Pigments are "browner" versions of the actual tone, and you need the warmth to mimic the hairs natural "raw" pigment. When using them, think again, THIN layer. It should not be a heavy application that sort of block the target color you apply second. To decide which color you use, think what is missing in the hair that will give the new target shade something to couple with. Ex. level 9 to a level 7 cool result. Pre Pig 20mls water 5mls Gold,5mlsKopper. Then apply target shade Topchic. 7NA/7GB. This allows me to create a neutral cool blonde that does not appear "ashen" or "flat".
Happy Coloring, and hit me up with any questions?
AMB
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