mehandi.com is the only site i trust to carry BAQ (art body quality) henna.
i love the henna, it has the properties of conditioning the hair and makes it healthy and shiney. the hair is thicker. the more you henna the better your hair will be. also, the deeper the color. the grays after 2nd or 3rd henna stay away, but with new growth you need to do touch up. chemical colrs only gives a coating but will fade.
i wash my hair the day before with a clarifying shampoo, no conditioner. only use BAQ Henna and lemon juice, wait for dye release, about 7 hours for Punjabi Prime, dampen hair and glop the stuff on saran wrap, shower cap and heated towel and wait 8 hours (the more glop the better for dye uptake)., this is my hair 7 days after henna ( it is a little windy out)
if you said you used henna from the store., you really don't know what you are getting. store hennas are compound hennas, they have metalic salts peroxide and ppd in them even tho the import manufacture doesn't
have to list them since they are not regulated to. they only list the plant(s) and any other so called natural ingredient.
check out mehandi.com and go to the link called henna for hair., there you will learn alot more. also go to the mixes page for henna on varying hair textures. BAQ henna isn't a dye, but a translusent color that builds on itself to give the shade of henna you crave.
henna is mood hair, in diffrent light it shows color diffrently.
i have photos on flcker
http://www.flickr.com/search/people/?q=greenf75

you'll see my henna hair and captions, i also uploaded my medium not quite dark mousey hair.