Freezing henna paste = Instant(ish) dye release?

[Cimorene]

I had heard that warm/hot liquid speeds up the dye release process, but doesn't it also cause a quicker demise of the henna? Or do you not have to worry about henna demise when you freeze it?

[diverbel]

Usually if you use boiling water you get instant dye release, but you also get faster demise of the dye release and the color may not last, actually fade a bit. I use hot black tea at the temperature that it is hot, but not uncomfortable, kinda like really warm bath temp. I wait till I just start getting dye release, then I put it in a ziplock, squish it flat and freeze. The color I am getting is almost twice as intense as nonfrozen henna.

[Alvrodul]

I have done the "mix and freeze" thing on several occasions - and I did not wait for dye release. I got the idea from some thread here, once upon a time - I think that the logic behind doing it that way was that the freezing would break the cell membranes and release the dye that way.
I certainly had excellent results!

[Cimorene]

I think I'll try a combined approach - mix the henna with warm (but not too hot) water, maybe wait a little while, then freeze it. I'll report back on how it goes when I take the henna plunge, so to speak!

[jackie_brown]

I usually prepare henna when i'm at home (on saturday or sunday), because i have time to wait until dye release (let it oxidized for 8/9 hours) then freeze.
This way i only have to take it from the fridge on evening and it's ready to be applied the day after (fully oxidized and at room temperature) at lunch or in first afternoon

[Courtney.P]

I did that today! worked great just in the bag smooshed around to mix and left to dye release for an hour the popped in the freezer!

[Katze]

Interesting topic.

I'm a henna artist, so I need to get the best staining power out of the henna I use (clients often want arms, backs, bellies...) and always wait 1-4 days for the best color.

Henna needs to be much fresher to dye skin, so maybe it doesn't matter if it is at peak staining power for hair? I am constantly amazed at the radical difference in which you henna heads mix.

We henna artists mix (with hot water or lemon - I usually get better results not using lemon) - then let it sit, then add monoterpene-containing essential oils, then let it sit again, then use for 2-5 days. But every henna is very different!

Just an example - the Rajasthani henna I used to use took 4 days to get its max color. The henna I use now takes about 36 hours, and it's also from Rajasthan. Colder, wetter weather means henna that isn't ready as fast, but keeps longer - hot, humid weather is ideal for a good stain but 'kills' henna paste faster.

I never freeze my henna. I've tried it and am not entirely comfortable with exposing the henna to those temperature fluctuations. Some henna artists I know do freeze, and are fine with it (though one artist I know who's been doing this for 25 years says she 'never freezes henna for brides' - brides traditionally need the best, darkest stain possible.) I've only been doing henna for 16 years so I bow to her.

As for the dye release theory, no one really knows how henna works (no scientist has actually researched it in a real lab) but it is as good a working theory as any. I always see the brown liquid or skin on top of my paste and think to myself, 'oh good, it's oxidized' - my own running theory.

[dollyfish]

A good rule of thumb is that all chemical processes go slower at colder temperatures and faster at hotter temperatures (hence why HOT water is better than COLD water).

So I would assume mixing and immediately freezing would halt (or at least drastically slow) the dye release process.

[Tisiloves]

I think it also depends on how long you leave it on for. IIRC one of the members on here mixes their henna and applies it immediately and then leaves it on overnight, so it starts dye releases on their head.

[cthulhuapproved]

From what I can gather, the dye release process isn't actually a chemical reaction, so freezing/cooling it won't necessarily slow it down. The dye molecules (lawsone) already exist in the henna plant's cells, so it's just an issue of getting them out of the cells and into the paste (and, thus, into your hair!). I almost always freeze mine immediately after mixing with tepid water or chamomile tea, and I get crazy dark stains every time---and I only leave it on my head for ~2 hrs. The 'skin test' leaves a significant stain on my wrist immediately after the henna thaws as well, which, to me, would indicate that the dye release has indeed already happened prior to application.

I remember someone else once suggesting that it could be due to the freezing process breaking up the cell wall, thereby releasing the dye molecule into the paste. To me, this seems like the most plausible explanation---consider a fresh blueberry: when first picked, it generally has only a blue skin and a yellow/green flesh inside, but if you freeze it, suddenly it's a gooey, dark purple-blue blob capable of staining everything within its reach. I know that this in particular is due to the expansive property of water as it freezes, so it doesn't seem like much of a stretch of the imagination that this could be the same mechanism responsible for getting henna to dye release through freezing only.

Or, at least, that's my semi-nerdy .