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Musings on washing fiber-based prints



 
 
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  #111  
Old March 9th 05, 12:59 PM
LR Kalajainen
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OK, I think we'e about run this thread into the ground. Here's my final
contribution. Last night I reprinted a neg that I'd done a few weeks
ago. Made two identical prints (fairly easy to do with divided
developer--gives almost 100% repeatability). One of them I processed
through several soaking washes not totaling more than 1 1/2 hours from
beginning soak to ending soak. The other, I left in overnight, and then
squeegeed it and put it on the drying screens. I cannot tell the
difference between the two prints visually. Both were done on Agfa MCC
111 (glossy, air dried). So my "totally scientific" conclusion is one
of two possibilities:

1. Even a very rapid soaking wash process leaches out the brighteners
(4 changes of water over a 1 1/2 hour period), OR

2. The brighteners don't leach out.

The highlights are crisp and creamy, gradations are delicate, the tones
aren't muddy, blacks are gutsy, and I'm happy with the look.

So until I can see a difference, I'm not going to worry about it.

Larry

Jean-David Beyer wrote:

wrote:

Jean-David Beyer

I think the UV consideration a bit trivia. So, whatever it is,
it will fluoresce in the very deep blue. I don't think it has
anything to with whitening/brightening. Personally, I don't
think I can see light at those wavelengths; 427-430nm.



My guess is that if you can see through a #47B filter, you can see 430
nm, because that is where its peak response is. The peak response Dr.
Henry got was in the 427-430nm range. He did not say there was no
other response. For a brightener to appear white, it would need some
response at longer wavelengths, perhaps. But in any case, since the
paper is excited also in the visual range, the brightener probably
just makes the reflected light slightly brighter and slightly bluer.

While I doubt quinine is what they use, you can sure see that quite
easily when it is excited with long wave ultraviolet bulbs; it looks
white - ever so slightly blue.

Everybody in this business knows the 'much ado about nothing'
the industry puts forth. My guess; many years ago some modest
change in coating of papers was made and, of course, the
much ado followed.



They put brighteners in laundry detergent. I do not recall any of it
claiming that, but some clothes "glow in the dark" when illuminated
with long wave ultraviolet. In the 1960s it was easy to see at disco
places. They do not make much ado about it: they just do it.

If Dr. Henry can't tell us of those coatings' composition we'll
have to ask those who coat there own for some information.



Dr. Henry is not likely to put out a third edition to his book, so we
should not expect new information from him. Those who coated the paper
when he wrote the second edition to his book refused to tell him what
they used. I doubt they will be anymore forthcoming these days. Now if
you know private individuals making their own silver-halide printing
paper emulsions, they can perhaps tell you what sizing they use (if
any), but no one will tell you what the major manufacturers use.

There
are likely a few with the information. As for going to the very
sources them self of the paper and it's pre-gelatin treatments
we may be out of luck; propriatory information. Dan



  #112  
Old March 9th 05, 03:46 PM
Lloyd Erlick
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On 7 Mar 2005 02:10:07 -0800,
wrote:


Jean-David Beyer wrote:
LR Kalajainen wrote:
It takes at least 24 hours of soaking before the brighteners begin

to
wash out. In prints left in water overnight from, say, 11 pm until

8
am, the brighteners aren't affected--- at least I've not been able

to
tell any difference visually.

Brighteners begin to wash out right away, ...


Just as well. The sooner they wash out the better. I recall
reading that the brightener titanium dioxide contributes to
peroxide production with attendent image degradation.
think whiteners are more used with RC papers. To easy to
measure loss of whiteners for there to be any question. Dan


mar905 from Lloyd Erlick,

How long do the brighteners last? Given an ideally
processed print, whatever that might be, do the
brighteners have a lifespan? Will they last as long as
the print, or 'wear out' some time before the print
dies? Will the print become less acceptable at some
time during its life because the brighteners have
stopped working? If the print is otherwise in good
condition, but the brighteners are worn out, is the
print less acceptable? Must darkroom workers make
prints expected to be 'good' only as long as the
brighteners are present, presuming the brighteners stop
working at some time. Since the brighteners work only
under some amount of ultraviolet light, what about
those of us who display prints mostly under
incandescent light? Is there an ideal level of UV, and
an ideal type of UV, for print display? Do the paper
manufacturers specify that level?

Just curious.

regards,
--le
________________________________
Lloyd Erlick Portraits, Toronto.
voice: 416-686-0326
email:

net:
www.heylloyd.com
________________________________
--

  #113  
Old March 10th 05, 12:00 AM
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To your eleventh question; yes to the first part but for "type of
UV" I've no preference. I suppose it would depend on one's mood
and what for that after dinner drink.

Why be so concerned, you use a warm silver Ilford MG.
Warm silver against a steely blue paper or at the very least a
most brilliant fluoresent WHITE! I'll check into it. I may
be right, an RC additive.

BTW, I'm working with that Ansco/Beers A. Last night I
mixed up another 1/10th batch and my first Beers B;
a little of the A plus all the B and I've Beers # 7. Dan

  #116  
Old March 11th 05, 03:39 AM
Jean-David Beyer
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wrote:
wrote:

I'll check into it. I may
be right, an RC additive.



I've checked into it. A lengthy article by Ctein in
Photo Techniques does include paper coatings.

Apparently I'm correct. The "photoactive" compound
titanium dioxide, "whitener", is used with RC papers. Barium
sulfate, baryta, is used with FB. The sulfate does not work
with polyethylene. All as of 1997.


Those compounds are not "photoactive" as brighteners. They are merely
highly reflective sizing used in the paper to make it a bit more opaque
and to increase the reflectance. They play little or no part in the effect
under discussion he the brightening of the paper by shifting invisible
(i.e., long wave ultraviolat) light into the visible spectrum.

Does one or the two of those wash out?


TiO2 is insoluble in water, so it does not wash out. BaSO4 is nearly
insoluble and does not wash out to any appreciable extent.

Or as some
other suggested, is something else going on? Or, as I now
suggest, nothing is going on that need concern us.
Dr. Henry's tests with ultraviolet light may have been
no more than curiosity getting the better of him. Did
he compare baryta with the dioxide?


Rather than second guessing Dr. Henry's tests, why not just read them? He
writes very clearly. He did not compare Barium Sulphate vs Titanium
Dioxide. There was no need to. He was testing brighteners, now paper
sizing agents.

That would be
testing RC vs FB.
And that's it; barium sulfate - FB, titanium dioxide - RC.
Dan

Which sizing is used in the paper (BaSO4 vs. TiO2) has nothing to do with
this discussion of brighteners.

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  #117  
Old March 11th 05, 04:34 AM
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Jean-David Beyer wrote:

Which sizing is used in the paper (BaSO4 vs. TiO2) has
nothing to do with this discussion of brighteners.


I don't recall Ctein using the word brighterers. The two
whiteners he does mention. He does not say that the dioxide
does fluoresce only that it will on exposure to light
contibute to peroxide production. Do you know for a
fact that the dioxide does not fluoresce?
I suppose Dr. Henry mentions both as they are, in your mind
two distinct entities. He does mention whiteners.? Dan

 




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