Re: HYB: pigment extraction

Thanks Chuck.

I ran into trouble by being impatient and wanting to use what I had on
hand, especially the slightly rancid vegetable oil that I was going to
throw away anyway <g>  Good point about the tint of the oil and the
tendency to emulsify if the specific gravities are close - takes a lot
longer to separate layers.  Because of respiratory problems, I'm not
going to use the solvents you prefer, but will certainly be more aware
of the constraints and interactions of what I do use!

Part of what got me into trouble was using water for the first
extraction, then adding alcohol without measuring!  The resultant
water-alcohol mix ranged in specific gravity from less than oil to more
than oil.  Water has specific gravity of 1 (heaviest), alcohol around
0.8 (lightest), vegetable oil around 0.9 (in between).   (methyl hydrate
is around 0.79, refined lamp oil is around 0.82).  So if I added a lot
of alcohol, the water-alcohol mix became lighter than 0.9 and migrated
to the top.  If I didn't add much and/or the alcohol evaporated, the
water-alcohol became heavier, and migrated to the bottom.  Add just the
right amount and specific gravity of the water-alcohol mix becomes the
same as the oil and they won't separate!  Perfect emulsion.  I think the
murky white layer I saw in the botched experiment was emulsion.  It
cleared overnight as alcohol evaporated and layers flipped.

Yesterday, when I repeated the experiment, I used carefully measured
amounts of alcohol (no water added), put both the jars in the microwave
at the same time to warm them a bit (warm to touch), dropped in about 4
square inches of fall petal.  The warm alcohol immediately leached out
the blue/purple pigments  without any mashing, so it was easy to fish
out the cleared pieces of petal without having to filter.

I didn't repeat with HARVEST OF MEMORIES yesterday, but I <thought> I
was seeing a bit of yellow color in the alcohol/water layer.  Very faint
and because there was so much pigment in the oil layer, I thought it was
my imagination.

<After experimenting with various oils I settled on clear lamp oil. Its
light and has no intrinsic colour to confuse results and is cheap and
readily available. Also no emulsion reactions with methyl hydrate (paint
thinner alcohol) which can confuse results. ......  If you are not sure
about what you are getting try using different original solvants.
.......The solvants I use work well together .I never would use cooking
oil. Too heavy, has emusions with a lot of alcohols and has a tint which
makes it hard to properly view extracted pigment.>

<You might try water extraction with HARVEST OF MEMORIES and then
                   filter and then mix with oil and shake. There is a
water based yellow
                   pigment ( a flavanoid) there as well as an oil based
yellow pigment..
                  Chuck Chapman>

--
Linda Mann east Tennessee USA zone 7/8
East Tennessee Iris Society <http://www.korrnet.org/etis>
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