One of the most frequently asked question in our workshop/salon is why hair that is no longer attached to a scalp should oxidize (turn lighter). A valid question, bu the rules that apply for growing hair continue to apply to cut hair, perhaps even more so. In the summer our hair naturally becomes somewhat lighter due to exposure to a lot more sunlight.
It is a myth that undyed wigs do not oxidize and dyed wigs do. I don’t know any 6 yr old girls with dyed hair, yet they all seem to get a little blonder/more highlighted in the summer!
All hair oxidizes slightly differently and at different rates due to many variables. Depending on the natural undertones (dyed or virgin) the color will lift either more to a golden/yellow or to a red/orange. Warmer browns will become more reddish/orange and cooler tones will become more gold/yellow. The vast majority of brown hair in the world, regardless of ethnic origin, is warmer in the tone (reddish/orange). The rate at which hair oxidizes also varies, and there is certainly debate as to which oxidizes faster – dyed or virgin, but generally if your wig has gone through 2 summers (not tropical or desert/semi desert) it probably needs a visit to the salon for dying or low-lighting (think hi-lighting just upside down). Generally a wig becomes lightest at the crown and hairline. This is due to being exposed to the concentration of UV rays. Wigs which have been dyed several times will oxidize faster as the natural f-layer (protective fatty acid) breaks down successively with each dying causing the hair to become more hydrophillic( water loving) instead of hydrophobic (water repellent), and the natural lubricating properties are removed. Hair is more susceptible to damage, feels drier, and is harder to detangle.
It is not uncommon to notice discoloration of your wig cap, lining or even the white scalp after having dyed or low-lighted your wig. Generally a hairdresser that is experienced with dying wigs will be careful not to touch the very root of your wig hair to avoid dying any material, however it is very unlikely that absolutely no dye will come in contact with any fabric. If in fact you do find noticeable stains (particularly on the scalp, you can request to have them faded using a solution used by hairdressers in salons to fade stains on client skin when dyes come in contact with actual scalp and forehead. This is not a perfect solution as it can take many treatments to fade the stain (usually repeated each time the wig is brought in for washing and setting), and many in fact never remove the stain completely. Replacing the top of the wig is certainly an option, albeit a very expensive one, and most often correct styling can mask any small stains that may remain on a wig scalp after dying or low-lighting.
* sample photo/ video of scalp stains vs no stains