I put a plate over the opening an left it alone.
It was a bit of a gamble, I thought, because when you prepare the flower of a banana, you must either wear gloves or smear coconut oil on your hands and under your fingernails because there is a substance in the flower that, when it oxidizes, turns black....which is just about the last thing my hair needs. I decided to do a test with some hair from my hairbrush.
I brought the twist of hair to the plant, removed the cover and found the banana bowl almost full of liquid. I set the hair in the bowl, where it sailed around, the breeze using stray hairs as a kind of sail, until I submersed it and replaced the lid.
A couple of days later, I retrieved the hair sample.
It seemed to have kept the colour, although it was a little hard to tell because of the fuzzballs from my hairbrush (I should have washed the sample first) and a few hairs that indicate the possibility that my husband used my hairbrush.
I dipped out the liquid.
I used it as a leave-in rinse (using no conditioner) and truly, my hair has not been shinier or softer for ages.
Thanks Liz Gilbert, both for your wonderful book and for this tip. I'm posting just so you know it works. Please tell your Balinese friend Thanks from me.