Hypo Clear Formula
Ian S
archives and could not find it.
Can anybody give me the formula/recipe for Hypo clear? From what I remember
I think it is 90% Sodium Sulfite and about 10% Sodium Metabisulfite, but I
do not remember the quantities to mix with water. Please help!
Thanks in advance!
Ian
Richard Knoppow
"Ian S" <ian1...@NOSPAMcomcast.net> wrote in message
news:qQkj9.114998$216.4...@bin4.nnrp.aus1.giganews.com...
is close to:
Home Made Wash Aid
Water 750.0 ml
Sodium sulfite, dessicated 100.0 grams
Sodium Bisulfite 25.0 grams
EDTA Tetra sodium salt 5.0 grams
Sodium Citrate 5.0 grams
Water to make 1.0 liter
For use take one part stock and four parts water.
This formula is buffered to neutral pH to minimise swelling.
The EDTA is important because it prevents deposition of
calcium from hard water on the surface of the film or paper.
Both the EDTA and Sodium Citrate are sequestering agents.
2% sodium sulfite will work with no additions but the
additions improve the results.
The Kodak research paper shows that maximum effect is
gotten in two to three minutes. There is little additional
decrease in washing time beyond a four minute treatment.
The working solution has a short life due to oxidation of
the sulfite, several hours in a tray is the limit.
--
---
Richard Knoppow
Los Angeles, CA, USA
dick...@ix.netcom.com
Dan Quinn
"...the formula/recipe for Hypo clear?" Following is what I found in
Patrick Dignan's Classic B&W Formulas.
Sodium sulfite, Na2SO3, 200 grams. Sodium Bisulfite, NaHSO3, 2 grams.
Water, H2O, to make 1 liter. Dilute 1 plus 9. Dan
Sandy King
dan.c...@att.net (Dan Quinn) wrote:
The important ingredient is sodium sulfite. If you prefer you can get the
same clearing by mixing up a fresh solution of 1% sodium sulfite and
discard after use, that is, 10g of sodium sulfite in 1000ml of water ( or
1g in 100ml of water, etc.). Sodium bisulfite functions as a preservative
for sodium sulfite in a stock solution but if you mix the sodium sulfite
fresh it is not needed.
Sandy King
Dan Quinn
"Sodium bisulfite functions as a preservative for sodium sulfite
in a stock solution..." A case may be made for that although lower-
ing the ph is the usuall stated purpose. The two sulfites' oxidation
may be slower in a more acid solution. That's the case with two part
developers. Dan
Sandy King
dan.c...@att.net (Dan Quinn) wrote:
Dan
Dan,
I think we said, or at least understand, the same thing. Lowering the pH
and creating a more acid solution is what preserves the sulfite. Without
the preservative the alkaline sodium sulfite solution will go bad very
quckly. The point I was trying to make is that the sodium sulfite is the
actual ingredient that clears the hypo.
Sandy King
PS
Darkroom Cookbook"
Hypo Clearing Agent (HCA)
Water (125 F / 52 C) 24 fl oz 750.0 ml
Sodium sulfite 7 oz 200.0 grams
*Sodium bisulfite 1 oz 292 grains 50.0 grams
Water to make 32 fl oz 1.0 liter
*The sodium bisulfite lowers the pH in order to prevent softening of
the emulsion of film. If paper is to be used, the bisulfite may be
left out in order to improve the paper's gloss.
To make a working-strength bath, dilute 1 part washing aid to 9 parts
water. After normal fixing, transfer the prints or film to the
washing aid with or without a water rinse. The water rinse increases
the capacity of the washing aid.
Water Rinse After HCA (with Final Running
Papers Fixer (optional) agitation) Water Wash
SW 1 minute 2 minutes 10 minutes
DW 1 minute 3 minutes 20 minutes
Film 30 seconds 1 to 2 minutes 5 minutes
Without the optional water rinse, 1 liter can be used for 20 8 x 10"
prints or 15 8 x 10" films, or the equivalent.
With optional water rinse, 1 liter can be used for 50 8 x 10" prints
or 40 8 x 10" films, or the equivalent.
Lloyd Erlick
sep2502 from Lloyd Erlick,
In other words, the formula represents two per cent sodium sulfite as a working
solution washaid.
Since the bisulfite is to prevent emulsion softening in film, can we delete it
in the case of modern films such as the Kodak T-Max films that are very durable?
What about the case where the worker is careful and handles the film as if it's
his own????
I should say I have been processing Tri-X, TMY, and others, for decades (since
it was released, in the case of TMY) and have never put sodium bisulfte in my
washaid (which is two per cent sodium sulfite). I always use my washaid once
only (I mix it directly to the dilution of a working solution. I store sodium
sulfite in dry powder form only.) I can remember not a single instance of
problems in the darkroom connected to film that is too soft (physically,
mechanically, that is; I've had plenty of soft negs that need more contrast...).
One of the main reasons I develop my own film is that I can handle it to my own
standard. I doubt I'm the only one with a darkroom of his own that absolutely
never gets scratched film for any reason.
In contrast, I've been seduced by the toughness of TMY to the extent that I
reticulated some Tri-X once when I put it into a fixer I had warmed up (winter
darkroom conditions...) to the temperature I could get way with with TMY.
An improvement to the washaid formula would be to add a small amount of sodium
hexametaphosphate (also sold as brand name Calgon) or one of the versions of
EDTA. This would help with water hardness, which can cause calcium compounds to
precipitate out of the solution onto the film. (This depends on how hard the
water is, of course. In Toronto, where I work, the water is only very mildly
hard, and I need only a quarter teaspoon of Calgon for three liters of working
solution washaid.) An equally effective (although likely more expensive) way to
deal with water hardness is to use distilled water for the washaid (no calcium,
no scum...).
If one has difficulty finding a sequestering agent like Calgon or EDTA for use
in a self-mixed washaid like two per cent sodium sulfite, I've had good success
with Kodak Hypo Clearing Agent. I've kept a pack of the stuff on hand to use a
half-teaspoon of the powder whenever I made up my sulfite washaid (three
liters). Kodak puts plenty of sequestering agent in it. It goes a long way in
this application! Calgon is the cheapest, though. It also dissolves very easily.
regards,
--le
-------------------------------------
Lloyd Erlick,
357 Richmond Street West,
Toronto M5V 1X3 Canada.
---
voice 416-596-8751
ll...@the-wire.com
http://www.heylloyd.com
-------------------------------------
Richard Knoppow
"Lloyd Erlick" <ll...@the-wire.com> wrote in message
news:3d919f07...@news.the-wire.com...
hense the 1:9 dilution rather than 1:4. 200grams/liter is
close to the saturation point for Sulfite so it may be hard
to mix and may tend to crystalize if it gets cold. however,
the life of the solution is better as it beomes more
concentrated.
The original paper describing Kodak wash aid states that
the reason for buffering is to reduce the diffusion path in
the emulsion to a minimum, which speeds up washing. While it
may be seen as preventing emulsion swelling the pH of a pure
sulfite solution is not high enough to be troublesome this
way.
Kodak wash aid contrains two sequestering agents: EDTA
tetra-sodium salt, and Sodium Citrate. Calgon is quite
alkaline and would need more bisulfite to neutralize it.
As far as the gloss of glossy paper be careful of
softening the emulsion too much if you ferrotype. Soft
gelatin tends to stick to the ferrotype surface. A pure
sulfite solution may raise the pH of the emulsion beyond the
point where the hardening is still effective.
Anchell's formula leaves out the sequestering agents which
are of some importance. The formula I posted is pretty
exactly what is in KHCA. Doubling the ingredients should do
no harm and will probably result in somewhat longer shelf
life, but again, its getting close to the point where
dissolving the sulfite may become difficult.
Dan Quinn
"A pure sulfite solution may raise the pH of the emulsion beyond
the point where the hardening is still effective." One percent
solutions run ph 9.6 and eight percent solutions run ph 9.8. Dan
Richard Knoppow
"Dan Quinn" <dan.c...@att.net> wrote in message
news:b379902d.02092...@posting.google.com...
I would have to look up the pH range for Alum hardener but
its not much on the alkaline side of neutral.
Preserving the hardening, or even using a hardener, may
not be an issue with many films and paper.
The use of sulfite rather than other alkalies is still
important because it is the specific ion exchange property
of the Sulfite which accelerates the washing. Alkali baths
accelerate washing _only_ when a potassium aluminum sulfate
hardener has been used. Where no hardener or where "chrome
alum" (potassium chromium alum) has been used the pH has no
effect on the washing time. Alum has a mordanting effect on
thiosulfate and silver complexes over range of pH on the
acid side of neutral. If the emulsion is made neutral or
alkaline the mordanting effect is elminated. By making a
wash aid neutral the mordanting effect is eliminated but
most of the hardening is preserved.
Kodak found out decades ago that film hardened in a chrome
alum hardening fixing bath washed out as fast as non
hardened film despite having a pH on the order of 2.5, much
more acid than a white alum hardening bath.
I doubt very much if there is a difference in wash rate
between a non hardening acid fixer and an alkaline fixer. I
am unaware of any chemical mechanism which would explain
such an effect. Perhaps someone else has the answer to this.
Michael Briggs
Richard,
How did you deduce the formula that you give? Is it from published
research by Kodak, or guesses from the MSDS, or ....?
--Michael
Richard Knoppow wrote:
...............
> There is no published formula. Kodak Hypo Clearing Agent
> is close to:
>
> Home Made Wash Aid
> Water 750.0 ml
> Sodium sulfite, dessicated 100.0 grams
> Sodium Bisulfite 25.0 grams
> EDTA Tetra sodium salt 5.0 grams
> Sodium Citrate 5.0 grams
> Water to make 1.0 liter
>
> For use take one part stock and four parts water.
.............