1 The Chemistry of Fading - This site, from Waxahachie High School in Waxahachie, Texas, discusses the chemical processes involved in fading caused by ultraviolet light. 2  Light and Color - The Franklin Institute- This site provides an introduction to how we see color.  Northeast Document Conservation Center.
https://www.loc.gov/rr/scitech/mysteries/colors.html
DON’T overheat. High heat can cause dull color by making the hair cuticles rough. If you can’t air dry, a tourmaline and ceramic grill blow dryer can help smooth cuticles without the damage. Flat irons can dry out hair, so use heat-protective products like sprays and serums to prevent damage.
http://www.healthscopemag.com/health-scope/color-treated-hair-care-dos-donts/
Hair | Hair Color. Avoid Brassy Hair Color. No one wants their hair color to look brassy. The general rule of thumb is the lighter you make your hair, the more likely it is to turn brassy since the process used to lighten hair opens the cuticle, allowing it to be more susceptible to damaging factors that can alter the color.
https://www.newbeauty.com/blog/dailybeauty/6972-avoid-the-causes-of-brassy-hair/
1 The Chemistry of Fading - This site, from Waxahachie High School in Waxahachie, Texas, discusses the chemical processes involved in fading caused by ultraviolet light.  Light and Color - The Franklin Institute- This site provides an introduction to how we see color.
https://www.loc.gov/rr/scitech/mysteries/colors.html
DON’T drown your hair. Research suggests that up to 80% of color fade is caused by water alone. Once you shampoo and condition in the shower, avoid letting the water run over your hair. When you do rinse, use lukewarm or cool water—hot water can cause color loss. DO protect your hair from the sun. UV rays fade hair color and dehydrate strands – even during winter months. Shampoos, glazes, and conditioners with SPF can help protect hair from sun damage year-round.
http://www.healthscopemag.com/health-scope/color-treated-hair-care-dos-donts/
You can dye your hair brown or black by using coffee. Get a rich, dark, unflavored roast and brew an entire pot. Allow the coffee to cool and pour into a basin in the sink. Work the mixture thoroughly through your hair by pouring and massaging it in. Allow the mixture to set for 15 minutes.
http://healthscamsexposed.com/2013/05/5-deadly-reasons-to-stop-dying-your-hair/
The color(s) we see are based upon these chemical bonds and the amount of light that is absorbed in a particular wavelength. Ultraviolet rays can break down the chemical bonds and thus fade the color(s) in an object - it is a bleaching effect. Some objects may be more prone to fading, such as dyed textiles and watercolors. Other objects may reflect the light more, which makes them less prone to fade.
https://www.loc.gov/rr/scitech/mysteries/colors.html
Chlorine can be to blame for brassy hair. “It causes a chemical reaction that counteracts with the actual tone of the color. Most of the time, it leads the hair to appear dull and dry looking,” says Jahanbigloo.
https://www.newbeauty.com/blog/dailybeauty/6972-avoid-the-causes-of-brassy-hair/
Hair | Hair Color. By NewBeauty Editors | December 27, 2014. No one wants their hair color to look brassy. The general rule of thumb is the lighter you make your hair, the more likely it is to turn brassy since the process used to lighten hair opens the cuticle, allowing it to be more susceptible to damaging factors that can alter the color.
https://www.newbeauty.com/blog/dailybeauty/6972-avoid-the-causes-of-brassy-hair/
While brassiness is hard to avoid, it isn’t impossible to avert. The sun is the number-one offender for brassy color, as it causes color to fade. That is why you should always keep color-treated locks protected from the sun. A scarf or wide-brimmed hat is an easy, chic way to preserve your color.
https://www.newbeauty.com/blog/dailybeauty/6972-avoid-the-causes-of-brassy-hair/
what causes hair color to fade off
Sun causes hair color to fade off. The sun is the number one offender for brassy color, as it causes color to fade.