differences in hypo-clear?

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kodak hypo-clear, perma wash, orbit bath, hustler rapid bath, etc.....

what are the differences between these products? which hypo clear is best? do they have different effects on the paper, drying, toning, or longevity of a print?

there are reams of information about developers and fixers and toners. but not so much on hypo clear. are they all just basically the same product leaching fixer out the prints? should a person simply buy the cheapest or fastest product?

-- james luckett (james@consumptive.org), May 03, 2001

Answers

I use a swedish brew containing potassium sulfite. I've heard that two table spoons of sodium sulfite in a liter of water will work just as good. Old photo books recommend a hydrogen peroxide solution. But I wonder if this is such a good idea since it maybe starts an oxidizing process of the silver. Hmmmmm....

Kodak HCA and perma wash can't be wrong.

-- Patric (jenspatric@mail.bip.net), May 03, 2001.


Hypo-clear is essentially a solution of sodium sulfite and sodium bisulfite; some commercial brews may have ingredients to prevent calcium from precipitating out etc, but they're essentially the same thing.

The formula is 20g sodium sulfite and 5g sodium bisulfite in a liter of water to make the working-strength solution. You can buy both from Photographers Formulary in large enough quantity to have HCA for an eon or two. Actually I wouldn't buy that much; they're hygroscopic.

Beware that manufacturers recommendations for washing may be _way_ too optimistic; I prefer the belt'n'suspenders approach of HCA and a nice long wash.

For lots of info, see "Mysteries of the Vortex," a big article on print washing that was published in _Photo Techniques_ magazine in three parts and was recently reprinted in one of their special editions.

Do _not_ use any sort of hydrogen peroxide hypo eliminator.

-- John Hicks (jbh@magicnet.net), May 03, 2001.


Many solutions can serve as washing aids, including the salt in sea water. In fact, water alone, i.e. distilled water seems the least efficient agent. The washing aid is supposed to work in several ways:

1) By improving the swelling of the gelatin Gelatin will swell faster in an alkaline environment. So mild alkalis, such as sodium carbonate, will help, too. Agfa recommends a 1% soda solution as a washing aid.

2) By removing fixer through ion exchange Certain salts in the washing aid may exchange with the hypo in the emulsion. This is fine, if the salt itself can then be washed out of the emulsion easier than hypo, as is the case with sodium sulfite.

3) By converting hypo to compounds that can be easily washed out Peroxides do this. They convert hypo to sulfate which washed out much faster, and which is also more stable. The down side of these hypo killers (as opposed to hypo removers) is that oxidising agents will not differentiate between good and bad, which means they will also oxidise the image silver and the paper. This may not be visible at once, but may have negative effects on the long-term stability of the pring.

I guess there are more effects, like forming complexes (for some hypo removers contain EDTA), but these are the principal effects.

Regards, Thomas Wollstein

-- Thomas Wollstein (thomas_wollstein@web.de), May 04, 2001.


I've never heard of Hydrogen Peroxide being recommended as a Hypo clear before, Potassium Permangante yes, Peroxide no. Permanganate in solution is a less aggressive oxidising agent, but can leave a bit of a browny tint on the print if it's overdone, which itself has to be washed out. It's more useful as a Hypo indicator, turning from pink to clear in the presence of even a small amount of fixer.

-- Pete Andrews (p.l.andrews@bham.ac.uk), May 04, 2001.

For interests sake:

Kodak HE-1

Water 500ml

Hydrogen Peroxide 3% 125ml

Ammonia solution (ammonia 28% 1:9 parts water) 100ml

Water to make 1.0L

Do NOT use this.

-- John Hicks (jbh@magicnet.net), May 04, 2001.



I have seen other old recommendations for using Hydrogen Peroxide, but why try these methods when there are better methods today that are safer for the films and papers stability in the long run. Today these recipes are only of historical interest as I see it.

-- Patric (jenspatric@mail.bip.net), May 05, 2001.

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