[Alt-photo] Re: Alt-photo-process-list Digest, Vol 807, Issue 1

[Francesco Fragomeni]

Hi Anne,

I didn't see this question until now but Tomas touched on some important
points. Chlorophyll-a is the most active of the light absorbing pigments in
plants for the purpose of photosynthesis. Obviously plants photosynthesize
using sunlight but what's important to note is that sunlight contains many
spectrums of different types of light, each of which have their own
particular importance to the photosynthesis process. Sunlight actually
contains only about 4% UV radiation so realistically not much compared to
around 52% infrared radiation and 44% visible light radiation.
Chlorophyll-a absorbs light most readily within the 400-450nm and 650-700nm
wavelengths, Chlorophyl-b absorbs 450-500nm and 600-650nm. Those ranges are
are within the visible light spectrum and fairly far outside of the UV
spectrum. UV-a is around 315-400nm, UV-b is around 280-315nm, UV-c is
around 200-280nm, and Vacuum UV (which is blocked by air but can operate in
a vacuum) is around 100-200nm. Not much of those UV wavelength ranges are
absorbed readily by Chlorophyl for the process of photosynthesis.

With that said, I'm sure something would happen but to what degree will be
for you to try out! I haven't tried working with chlorophyl prints in a uv
box so I can't tell you for sure one way or another what will happen but I
suspect some result will occur but probably not what you would expect when
using direct sunlight.

Best,
Francesco
www.francescofragomeni.com


On Fri, Feb 14, 2014 at 10:56 AM, Tomas Sobota <tom at sobota.net> wrote:

> Anne, I expected that someone more knowledgeable than me would answer your
> question, but since nobody comes forward ...
>
> If by "chlorophyll prints" you mean something like the juxtaposing of a
> negative on a living plant leaf to get after a time a positive image, my
> answer to this would be an unambiguous "who knows", never having attempted
> this technique.
>
> Looking at absorption spectra of chlorophyll a and chlorophyll b, for
> example here: http://www.biologie.uni-hamburg.de/b-online/e24/3.htm
> it is apparent that chlorophyll as a whole is mainly sensitive to the red
> and blue regions of the spectrum, with a strong cut-off towards the near
> UV. This, at least in theory, would preclude the use of UV light sources.
>
> Again, producing an image this way using strong sunlight needs many hours
> or even several days of exposure, do you really mean to have your UV bank
> on for such a long time?
>
> But if I were you I would try, who knows ...
>
> Tom
>
>
>
>
> On Thu, Feb 13, 2014 at 7:16 PM, Anne Chansonette <chansonette at gmail.com
> >wrote:
>
> > Does anyone know if it is possible to do chlorophyll prints using a UV
> box
> > instead of natural light? I am currently in the grey and unending New
> > England winterland and don't want to wait months before working on a
> > project!
> > Anne at lesleyU
> >
> > Sent from my iPad
> >
> > > On Feb 21, 2013, at 7:00 AM,
> > alt-photo-process-list-request at lists.altphotolist.org wrote:
> > >
> > > Send Alt-photo-process-list mailing list submissions to
> > >    alt-photo-process-list at lists.altphotolist.org
> > >
> > > To subscribe or unsubscribe via the World Wide Web, visit
> > >
> http://lists.altphotolist.org/mailman/listinfo/alt-photo-process-list
> > > or, via email, send a message with subject or body 'help' to
> > >    alt-photo-process-list-request at lists.altphotolist.org
> > >
> > > You can reach the person managing the list at
> > >    alt-photo-process-list-owner at lists.altphotolist.org
> > >
> > > When replying, please edit your Subject line so it is more specific
> > > than "Re: Contents of Alt-photo-process-list digest..."
> > >
> > >
> > > Today's Topics:
> > >
> > >   1. Re: Gelatin (Michel Debar)
> > >
> > >
> > > ----------------------------------------------------------------------
> > >
> > > Message: 1
> > > Date: Wed, 20 Feb 2013 23:55:36 +0100
> > > From: Michel Debar <michel at debar.org>
> > > To: The alternative photographic processes mailing list
> > >    <alt-photo-process-list at lists.altphotolist.org>
> > > Subject: [alt-photo] Re: Gelatin
> > > Message-ID:
> > >    <CAOtyDPLifUi342p44Anj5k2orcXT=fZkg=JtZfT3y_FqMRzLWw at mail.gmail.com
> >
> > > Content-Type: text/plain; charset=UTF-8
> > >
> > > An amazing quote from Douglas Cockerel 1910 book, Bookbinding and the
> > care
> > > of books :
> > >
> > > [...]
> > > The following is quoted from ?Chambers? Encyclop?dia? on Gelatine:?
> > >
> > > ?Gelatine should never be judged by the eye alone.
> > >
> > > ?Its purity may be very easily tested thus: Soak it in cold water, then
> > > pour upon it a small quantity of boiling water. If pure, it will form a
> > > thickish, clear straw-coloured solution, free from smell; but if made
> of
> > > impure materials, it will give off a very offensive odour, and have a
> > > yellow, gluey consistency.?
> > >
> > > [...]
> > >
> > >
> > > ------------------------------
> > >
> > > _______________________________________________
> > > Alt-photo-process-list | http://altphotolist.org/listinfo
> > >
> > > End of Alt-photo-process-list Digest, Vol 807, Issue 1
> > > ******************************************************
> > _______________________________________________
> > Alt-photo-process-list | altphotolist.org
> >
> _______________________________________________
> Alt-photo-process-list | altphotolist.org
>