In my descriptions of how hair color works, some hair color will be tagged (+ color) and it will only add color .... say a Level 3 or level 4 color.....those colors are (+ color) only colors. There are colors that are "lifting color" or will actually bring existing color out of the hair, so those colors will be called (-color)...then there are colors that are (+ & - COLOR). When you apply color to the hair, you are adding (+ color) color...............so color + color = MORE color, so the hair has more pigment.
If the color used is addition only, the hair will often but not always be darker. Deposit (+ only) tints are often used as "TONERS" which is described as:changing the tonal value of the hair without changing the lightness or darkness of the actual color of the hair. This is the least complicated method of tinting the hair. Any time the hair is lightened, no matter how little, you are subtracting pigment or (- COLOR). When subtracting color from the hair, one sees a imbalance of natural pigments, as you are altering nature.
Remember when the 3 primaries are mixed in exact equal amounts....what color do we get?
We get black/gray.
Uneven amounts of the primaries = brown (shades of). That is why knowing the color wheel is important, because every person's hair is derived from the color brown. Black is just a dark-dark brown......and blonde is simply a super super light brown. All colors of hair are derived from the main color brown.
If there is more yellow than red or blue, the brown will be light, even beige. If there is more red than the other two primaries, the brown will be warm brown. And if there is more blue than yellow or red, the brown will be dark and cooler looking.
All virgin hair is a shade of brown: it contains all 3 primaries...which is why understanding the LAW of COLOR is so important to the end result in hair coloring
Dominant Underlying Remaining Pigment
So as you begin to lighten color at any level (you are not actually dealing with brown, you are dealing with the DURP - which is usually red,orange, gold, or yellow.
Every single one of you complains about the "warmth" when you begin to lighten the hair. BLUE is the first color to leave the hair in the lightening process, which leaves Red & Yellow to the eye....100% complete warmth and unappealing to the eye. Although I suspect if things were different and the warmth left the hair first, then to the human eye "warmth" would be the appealing tonal category. That just rings true to the "we always want, what we cannot have ... verbiage . Don't you think?
** Balanced hair coloring comes when all 3 primaries are present. When hair undergoes lightening (pigment is subtracted), even slightly, there will be an imbalance of the primaries.
** Color companies always have separate tonal series, with a GOLD, RED, BLUE/VIOLET, GREEN, Natural.