B&W film developing questions

"Ken Hart" <kwhart.DeleteThis@fullnet.com> wrote in message
news:flscha$pqm$1@aioe.org...
>
> "G.T." <getnews1.DeleteThis@dslextreme.com> wrote in message
> news:13o36j825t8r910@corp.supernews.com...
> snip
>> So in this workflow it would be develop, stop, fix, hypo,
>> wash, and wetting agent? In class we washed prints in
>> hypo but not film.
>>
> Just for the record. "fixer" and "hypo" are basically the
> same thing. I realize that when you say "hypo", you mean
> "hypo clearing agent"(sometimes called "HCA"). The purpose
> of the hypo clearing agent is to remove the hypo or fixer
> from the film or print.
>
> Back in the 'good old days' when prints were actually
> paper and not resin-coated plastic stuff, the paper print
> would soak up a lot of chemicals. You needed to wash a
> print for perhaps an hour or so to remove all the fixer
> from the porous paper. (Ricard K., please feel free to
> jump in and correct me or elaborate-- I'm certain you are
> far more knowledgeable on this!). A hypo clearing agent
> would neutralize the hypo (or fixer), so that a shorter
> wash time (perhaps 30 minutes?) would suffice.
>
> Film, being a non-porous material (or certainly less
> porous than fiber-based prints) doesn't soak up as much
> chemistry, so a hypo clearing agent is not as important.
> If it's critical to you that your negatives last to the
> next millenia, than you may want to use it anyway...!
>
> As for not being able to print at home, there are many
> people who make do with printing in a bathroom. Some use a
> cart (Rubbermaid? Check office supply or food service
> supply companies.) to hold their enlarger and store their
> chems, trays, and stuff so they can wheel everything into
> the bathroom for a session, then wheel it all into a
> closet for storage. You can put velcro around the window
> frame and stick a piece of faric or cardboard over the
> window. There is also a gentleman who espouses 'one-tray'
> processing. I've never tried it myself, but perhaps for
> the temporary darkroom, it may be the answer. Maybe
> someone here can supply the link to his website, or to
> websites for temporary darkrooms. Using the kitchen is
> also a possibility, but some people don't like that idea
> because of the possibility of food being contaminated--
> but for darkroom work, cleanliness is important, so wipe
> up those chem spills!
> For me, you can take away my permanent darkrooms when you
> can pry the staticmaster brush from my cold, dead fingers!
>
My darkroom pretends that is a kitchen much of the time.
Quite small but Peter Gowland, in one of his books, says
that a darkroom can be too big. I agree with this, it must
be small enough so that things are within easy reach.

Fiber prints (the support should really be called
unprotected paper) does soak up hypo. The use of a wash aid
helps to dislodge it from the paper but the washing is not
by simple diffusion as it is for the emulsion because some
of the hypo gets bound up with the paper fibers mechanically
(Ilford points this out in their paper on accelerated
washing). As a result wash times are much extended.
Actually, the emulsion will wash out as fast as RC paper but
the support does not. Also, the "baryta" layer under the
emulsion tends to bind hypo as well. A sulfite wash aid will
break the bonding of hypo and fixer reaction products to the
emulsion and the baryta layer and, to some degree, with the
paper fibers but it is not as effective with the fibers as
with the emulsion and baryta layer. So, even with a wash aid
treatment fiber prints take 10 to 30 minutes to wash out. RC
paper even when fixed in acid hardening fixer will wash out
in about 4 minutes. Because a very small residue of hypo has
been found to stabilize the image silver against oxidation
wash times for RC should not exceed the recommended 4 or so
minutes and times for fiber paper or film treated with wash
aid should not be extended. Of course toning provides much
more effective protection and should be applied to prints
especially but, nonetheless, one can wash too much.
The substrate of RC paper is also plastic. In fiber
paper the substrate is one or more layers of very hard
gelatin with a suspension of barium sulfate (baryta) in it.
Barium sulfate is one of he most reflective materials around
which is why it was chosen. The substrate of RC paper is
plastic with a suspension of titanium dioxide in it. TiO is
even more reflective than barium sulfate. Because the TiO
tends to emmit an oxidizing gas which attacks both the image
and the plastic layer RC papers have had problems with
having short lives in the past. However, for at least ten
years all RC papers have been made with anti-oxidants and
oxidizer scavengers built in so they no longer have this
problem. The scavengers are supposed to be self-regenerating
so the protection should last as long as the print is
intact.
The difference in the substrate may have something to do
with the difference in appearance of the two types of paper
although I find that when other than glossy surfaces are
used its very difficult to tell them apart.


--
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Richard Knoppow
Los Angeles, CA, USA
dickburk.DeleteThis@ix.netcom.com

Geoffrey S. Mendelson wrote:
>
> When I was a teenager, I had to work in a windowless bathroom.
> The trays went in the tub, and the enlarger sat on the toilet.
_____
My first darkroom in Vancouver, Canada was the same; a windowless
bathroom. I would place two rubber padded 2x4s on the bathtub, and put
the enlarger on it. The trays (11x14 was biggest size i could do) would
sit on the counter by the sink. To do exposures i would sit on the
toilet lid facing the bathtub/enlarger. I second the idea of using a
drum plus motor base. You can easily make your own drum(s) from 4 inch
black drain pipe and develop/stop/fix/wash prints that way. Use a large
O-ring in the center of the drum to stop it from rolling itself off the
base.
--
Regards / JCH