If you apply cassia or henna and the results are dingy, brownish, or blackish, there may be minerals, metallic salts, or alkalinity in your local water supply that are reacting with the quinone molecules, lawsone (in henna) or chrysophanol (in cassia). If these minerals or metallic salts are present in your keratin either through absorption through the water you use for drinking or showering, they will darken your henna and cassia colors, often to a very disagreeable shade.
If your hair test shows a muddy color, determine whether you have hard water or other mineral contaminants in your water supply. Do your tea kettle, faucets, and drains develop a buildup of minerals over time? Does soapy water scum over rather than creating bubbles when you slosh it around? Was there mineral, metal, or coal mining, or petroleum production by pumping, fracking, or extraction in your area? Minerals, metallic salts, and ions may have leached into your water system from man-made and natural sources. Your water district may be providing water that is harmless and safe to drink, but which has compounds that will interact with henna and cassia.
Read more:https://www.mehandi.com/v/vspfiles/downloadables/chapt12_troubleshooting.pdf
Links to specific topics in this chapter:
Why Are My Cassia and Henna Turning Brownish, or Worse? (hard water problems)
