Some friends and I have been working on the concept of lightening hair colour naturally. I summarized what was done here on this forum
http://forums.longhaircommunity.com/showthread.php?t=62261.
One person had her hair redarken following Recipe 2 for Hair With Multiple Layers of Henna - I think Reference 10, which I added yesterday addresses that.
That person is now experimenting with citric acid and sodium citrate and has lightened her henna to some degree -henna is not supposed to be removable once bound - most online suggested treatments for removing henna do not work on henna that is oxidized. The idea is to return her hair to her base colour not lighten or destroy pigment in the process as peroxide can.
I have 2 questions please.
Does anyone have any theories on whether it is possible to break the bond henna forms with keratin? The most common answer is cut off the hair?
And is that reference on anthocyanins a plausible explanation as to why the hair redarkend some time after the treatment?