Re: Bleach-development with gum recipe
Hmm. I think we must be talking past each other, or I'm too tired to
be coherent, which is quite likely. I was responding to your
proposal that we forget the water because the water makes no
difference; to me the prints show that the water makes a good deal
of difference, even if it's just a little water I, by the way,
prefer the print without the added water, the one with darker DMax
and more contrast. I'd probably let it develop a little longer, if I
hadn't been standardizing the development for comparison, but I
think it's a much better print, even a little underdeveloped. I
don't care for the flatness of the other one, and it's interesting:
I guess this also offers some support for the theory that adding
water promotes pigment stain, because there's some stain in the
highlights. I've never credited that theory much, but then I've
never added water to my mixes either.
I thought I gave all the details on the page, but would be glad to
answer any other questions. The amount of gum should be the same in
both, as I simply added a little water to the total rather than
changing the gum.
I'm not sure what you're seeing in this, but it certainly doesn't
convince me that I'd want to add water to the mix, quite the contrary.
About the flood: Mostly it's a matter of waiting for a dry day and
putting things outside to dry out, but the canvases, including fresh
stretched canvases and also finished paintings, are stained at the
water line, and I don't know if they can be fixed; also some of the
stretchers are warped out of shape. Otherwise everything is just
waterlogged. The papers in the flat file didn't get wet, but they're
very damp just from the dampness in the air, and all the blotters are
wavy instead of flat. Thanks for asking.
kt
On Dec 4, 2007, at 5:29 PM, Marek Matusz wrote:
Katharine,
Sorry to hear about all the mess that the storm brought. I was
listening to a story about it on NPR while driving home and was
thinking on how you fared.
How in the world did you find the energy to print this test?
You did not give all the details of the test, but I think it
illustrates my point precisely. Your second print is lighter and
has more tonal gradation, as would be expected from a thinner gum
layer and by the way they are an excellent illustration of the
mastery of the process that you aquired.
I would assume you diluted the gum solution but used the same
volume of solution for both tests. A better test to convince
yourself would be to dilute, but then backcalculate the dilution
and measure more volume of the dilute solution so that the amount
of gum on the print is the same. But I can already see you might be
convinced by the though process without doing the experiment.
ANd of course the residual moisture or air moisture plays a role in
gum because it dictates how gum dires.
Marek
Hope your loses are not all that bad
> Date: Tue, 4 Dec 2007 16:04:30 -0800
> From: kthayer@pacifier.com
> Subject: Re: Bleach-development with gum recipe
> To: alt-photo-process-l@usask.ca
>
> Hi Marek,
> I got distracted with paper negatives and with a flood in my
painting
> studio/framing workshop -- what a mess. Ruined canvases and paper,
> soggy boxes (that hadn't been unpacked yet) and so forth. So I
> haven't got back to the bleach thing yet.
>
> Anyway, I've been thinking about your post and trying to follow the
> numbers (I may need help in understanding how you've derived some of
> these numbers, maybe later) but mainly I'm having trouble getting
> past the first two sentences. I can't agree with your basic
> premise that water makes no difference to the emulsion, since it is
> just added to improve spreading and is evaporated, so we can just
> eliminate it from the calculations. It seems, on the face of it, to
> make sense, but unfortunately for the simplicity of the argument,
> water does make a difference in my experience.
>
> At any rate, between mucking out the flood, I printed two pictures
> where everything is the same except that one has a little water
added
> to the mix, just to check my own experience and perception that
water
> in the mix does make a difference, even if the water is dried out of
> the emulsion before printing:
>
> http://www.pacifier.com/~kthayer/html/Water.html
>
> As far as the bleach discussion, I don't think it's either here or
> there, since by either way of calculating it, we agree that I'm
using
> more pigment, and I'll be backing the pigment down when I come back
> to try the bleach thing again.
>
> I'm sorry; you'll never get me to use powdered pigment, though it
> would make comparisons much easier.
>
> Great discussion, thanks!
> Katharine
>
>
>
>
> On Dec 3, 2007, at 7:01 PM, Marek Matusz wrote:
>
> > Katharine,
> > I would like to simplify the discussion of gum solutions by
> > omitting water from all discussions. After all water is only
> > incidental in helping spread the sensitizer and making the
> > solution. Therefore use of saturated or diluted dichromate is also
> > of no grat importance. Once the paper is coated and dried, water
> > has no bearing on composiion, it has evaporated. I would like to
> > propose to express things basis the actual sensitive gum layer
> > concentration. That is a ratio of dry pigment to dry gum and ratio
> > of dry dichromate to dry gum. These are concentrations of both
> > components in solid gum solution.
> > Let's take the water out. Is is not present in the gum layer when
> > you are exposing it to UV light.
> >
> > Hereis what I have for your and mine ratios:
> >
> > MY GUMKatharine
> > 14 baume gum, 25%2510
> > dry gum at 0.25%, g6.252.5
> > dry pigment, g0.6250.75
> > additional gum, g(paint)1.5
> > (NH4)2Cr2O7 sol1210
> > Cr2 from sol, grams3.63
> > pigment/gum0.10.1875
> > Cr2/gum0.5760.75
> >
> >
> >
> >
> > SO it seems our dichromate concentrations are very similar, but
you
> > have about twice as much pigment by this calculation. To roughly
> > check and crosscalibrate your method, I took a lamp black
> > watercolour paint and diluted it with 14 baume gum The solution
> > consisted of 3 grams of lamp black paint in 10 cc of gum. I did
the
> > smudge test on this and my 2.5% gum stock. I have to say from
> > visual observation that my stock is somewhat (but not much) darker
> > then what I have from the watercolour paint, but the calculations
> > above show that youI should have more pigment (I can send the jpeg
> > of the smudge test). I am inclined to think that the paint is less
> > concentrated then 25% or the pigment is less black.
> > ANother observation is that with so much paint one can bring a
> > substantial amount of extenders, and other substances used in
> > paints and that can alter properties of gum solution.
> > I would suggest buying carbon black from Daniel SMith. It is very
> > inexpensice (a few $ per lb) and allows for a controlled
> > experimentation.
> > The discussion is great though.
> > Marek
> >
> > > Date: Sun, 2 Dec 2007 12:35:02 -0800
> > > From: kthayer@pacifier.com
> > > Subject: Re: Bleach-development with gum recipe
> > > To: alt-photo-process-l@usask.ca
> > >
> > > Thanks! That's helpful. I was thinking you were working with a
> > > dilute dichromate and that maybe my mottling had something to do
> > with
> > > using saturated ammonium dichromate, but obviously that's not
it,
> > > since you're using the same
> > >
> > > So many differences. First the pigment: Even if I had a way to
> > > weigh my paint, comparing our actual amounts of pigment would be
> > > difficult and could only be a ballpark estimate, since
there's no
> > > way to tell how much actual pigment is in a given amount of
paint.
> > > But using Bruce MacEvoy's figure of 20-30% pigment/vehicle for
> > carbon
> > > black, I'll use 25% as a middle figure to ensure a conservative
> > > estimate, although M. Graham tends to be on the high end as
far as
> > > pigmentation of their paints. Then considering how much of
the tube
> > > I squeezed out into around 10 cc of gum --- I'd guess 1/5 of the
> > > tube, or 3 grams of paint. That's a LOT of lamp black, but
following
> > > Marek's specification of a "highly pigmented" mix, I wanted to
> > really
> > > load it up. Okay, 25% of 3 cc= .75 grams of pigment in 10 ml
gum,
> > > waving aside the little difficulty about the density of gum
and all
> > > that, gives 7.5%. It's not exact, but probably not all that far
> > > off, and I think I'm satisfied that it corroborates my
evaluation of
> > > this mix as heavily pigmented. That was the first mix; the
second
> > > one I derived by adding around 5 cc gum to the first mix.
> > >
> > > Oh, but then you add water, which dilutes the pigment as well; I
> > > don't add any water to the mix. So a more comparable figure
than %
> > > pigment in pigment mix would be % pigment in total coating mix.
> > > Here's how I figure it, and I hope someone will check my
figures,
> > > because while I'm pretty good at statistics, I've never been
> > great at
> > > simple arithmetic: For Marek: 2.5 g in 100cc = .025 g per cc. So
> > > 12 cc's contain .3 g pigment. Total mix = 12 gum/pigment plus 12
> > > water + 6 dichromate solution= 30 cc total mix (never mind
that the
> > > sum of the liquids might not add to 30 for a number of reasons;
> > we're
> > > just getting a number to compare, here) so .3 g pigment in 30 cc
> > > total solution = 1% pigment to total coating mix.
> > >
> > > Then mine: the pigment mix contains an estimated .075 g
pigment per
> > > cc gum. my coating mix consists of 2.5cc of pigment mix, so
2.5x .
> > > 075 = .1875 g pigment. Total mix = 2.5 cc gum/pigment + 2.5 cc
> > > ammonium dichromate soluton = 5 cc total mix. .1875 g pigment
in 5
> > > cc total = 3.75% pigment to total coating mix.
> > >
> > > That was a lot to go through to convince myself that I'm
using more
> > > pigment as a proportion of mix than you are, but I needed to be
> > > convinced for sure. So I can cut back on the pigment by at least
> > > half and still have what you would call a "highly pigmented" mix
> > that
> > > can be brushed out thin. Half as much pigment will give a mix
that
> > > will brush out thin; I prefer to reduce the amount of pigment
rather
> > > than adding liquid.
> > >
> > > I don't like Fabriano paper, and recently used up the last of my
> > > sample of Fabriano Artistico extra-white running some test
prints
> > > just to get rid of it, so our papers will have to be an
uncontrolled
> > > variable, also sizes, as I like glyoxal.
> > >
> > > We've got a big storm blowing in this afternoon, and this is
helping
> > > distract me from the sound of the wind. Unfortunately, I put the
> > > car in the garage to protect it from flying branches etc, and
now
> > > it's really hard to get to my darkroom, which opens off the
side of
> > > the garage. I prefer to leave the car outside and use the garage
> > > as a lobby-area for the darkroom (speaking of Judy's
> > characterization
> > > of our wide-open spaces out here in the west).
> > >
> > > Report to follow, unless the power goes out. Over,
> > > Katharine
> > >
> > >
> > > On Dec 2, 2007, at 11:14 AM, Marek Matusz wrote:
> > >
> > > > Here is my recipe for sensitizer for bleach develop:
> > > >
> > > >
> > > >
> > > > Gum pigment solution:
> > > >
> > > >
> > > >
> > > > 100 cc of 14 Baume commercial gum 2.5 grams of Daniel Smith
carbon
> > > > black powder, 4 drops of jet dry. Jet dry is an automatic
> > > > dishwasher rinse aid. I found this detergent very helpful in
> > > > dispersing carbon black powder, which is difficult to wet.
Jet dry
> > > > is a miracle detergent for me to help with coating, reduce
> > bubbles,
> > > > etc.
> > > >
> > > > All that mixed in a mixer for a few minutes. Last batch (0.5
> > > > liters) was made several months ago. I just shake it before
using.
> > > >
> > > > I call it a 2.5% carbon solution, although in reality it is
> > higher,
> > > > since gum density is less then 1.
> > > >
> > > >
> > > >
> > > > Preparing sensitizer:
> > > >
> > > > 12 cc of gum pigment solution, 12 cc of water, 6cc of 30%
ammonium
> > > > dichromate. This gives me the right consistency for my coating
> > > > method. It is also optimum in terms of having enough water
to wet
> > > > the paper and keep it moist long enough to smooth the coat,
but
> > not
> > > > to keep it too wet. My paper has been Fabriano Artistico
white and
> > > > extra white since my first tricolor gum a few years back. When
> > > > sized both papers act in the same way. I suppose I am so
addicted
> > > > to that paper that if they ever stop making it I'll have to
quit
> > > > printing.
> > > >
> > > > Sieze is two coats of 3.5% gelatin hardened with
glutaraldehyde or
> > > > recently with dichromates. The examples on the web site
were made
> > > > on paper hardened with dichromates.
> > > >
> > > >
> > > >
> > > > Exposure is 3 minutes under UV BL light bank. My typical gum
> > > > exposure is 45s to 1 minute.
> > > >
> > > >
> > > >
> > > > Development:
> > > >
> > > > Soak briefly (1-2 minutes) in water to remove dichromates.
Soak in
> > > > bleach solution (20ml of bleach/liter) for 1 to 5 minutes,
finish
> > > > developing in water. 30 minutes to 2 hours are my typical
times
> > for
> > > > water development. If development is very slow go back to
bleach
> > > > for a few minutes. I change or replenish bleach every 2 or 3
> > prints.
> > > >
> > > > Have fun printing
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Connect and share in new ways with Windows Live. Connect now!
> > >
> >
> >
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> > Join in!
>
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