Dye

Wool dyes are items used to change the color of wool. There are currently 16 dyes, including seven "primary" dyes (red, yellow, blue, green, white, black and brown), seven "secondary" dyes, and two "tertiary" dyes.

History
Wool dyes were added in the Beta 1.2 update.

Update 1.1 gave sheep the ability to regrow their wool by eating grass. Dyed sheep will regrow wool in their new color.

Uses
Dyes can be placed with wool on a crafting table (in any position) to dye a single block. It can also be used on sheep to paint them. After shearing, the wool dropped will be of the painted color as well, sometimes yielding more colored wool than from crafting (see Notes section). Not all the dyes are renewable, but the colored wool itself is; after shearing colored sheep, they will regenerate their wool by eating grass (11w49a). Additionally, there are naturally occurring gray, light gray, black, brown and pink sheep that drop corresponding color wool as well. Note, that you can only dye white wool via crafting – painting colored sheep is the only way to dye non-white wool. For example, you can get "bleached" wool by using white dye on a colored sheep.

Primary Colors
These primary dyes (with the exception of cocoa beans) are created from a single ingredient spawned naturally in a world.

Secondary Colors
Secondary dyes are created by combining primary dyes together.

Tertiary Colors
Tertiary dyes are created by combining at least one secondary dye.

Data Values
The color of a dye item depends on a secondary data field (beyond the item ID of 254), which is also used to store the damage for tools and so is commonly referred to as a “damage value”.

Trivia

 * The reversed color values closely resemble an ANSI or VGA palette with the biggest outlier being Orange.
 * The metadata values for the Wool and Wool Dyes are the inverse of each other, with White Wool having 0, Bone Meal 15; Orange Wool having 1, Orange Dye 14; etc.
 * Giving yourself a dye with damage value bigger than or equal to 16, will be in result of it looking like a random item, at first it looks like a wooden tool. Moving the mouse over it to get the tooltip will crash the game.
 * Dying sheep is more efficient than dying wool, as one dye can be used to get endless colored wool, as long as the player has shears.
 * When updating a world to 1.2 all dyes seem to reset black (inksack) (Tested in SMP, haven't checked in SSP)