I don't know the scientific reason but to me it's kind of like your windows getting dirty. Windows/grey hair have little or no color. Smoke, pollution, minerals in the water, dust from the furnace, hair products, etc all add a layer to the surface of your windows/hair.
I spend alot of time in the sun in the summer and it also makes my hair get a yellow tint to it.
And heat from curling irons/flat irons/blow dryers can make grey hair very yellow. I honestly don't know how people deal with that who use heat stylers on their hair every day. My sister ran her new flat iron through a strip of my hair one day just to see if it would straighten my tough hair and it instantly turned it a very dark yellow color. Ick.
In Western PA
Found NC in 2004. CG since 2-05, going grey since 9-05. 3B with some 3A.
Hair texture-medium/fine, porosity-normal except for the ends which are porous, elasticity-normal.
Suave & VO5 cond, LA Looks Sport Gel, oils, honey, vinegar.
http://public.fotki.com/jeepcurlygurl/ password jeepy **updated August 2015**

Last edited by jeepcurlygurl; 01-30-2014 at 03:10 PM.