It turns out that Locks of Love takes dyed hair, so I will also donate to Locks of Love if you have dyed hair but you want to donate.
The requirements for Pantene's Beautiful Lengths program are as follows:
-no chemical dye in the hair
-at least 8 inches long
-only 5% gray hairs can be in the hair donated
The requirements set for the dyes and colors of hair were set because if the hair has dye or gray color, the dye used when the wigs are colored will be affected differently with unnaturally colored hair or gray hair.
The requirements for Locks of Love are as follows:
-dyed hair is ok as long as it was not bleached before the dyeing process
-layered hair is fine if the longest layer is at least 10 inches
-at least 10 inches long
-gray is ok, but it will be sold for manufacturing costs
If you do not have any hair to donate, you could always send a monetary donation. Locks of Love accepts checks, but there is no information that I can find about money donations to PBL.
