Mixing Hypo Clearing Agent

[Max Power]

Hi All,

A year or so ago, a friend gave me a box of old photochemistry he had dug out of a high-school darkroom. In that box was an ancient box of Kodak Hypo Clearing Agent. There were three small aluminium bags still intact inside; the contents of these small bags are totally dry and undamaged. Seeing that I'm going to be using FB paper for the Group Print Exchange, I thought that it would be wise to use Hypo Clearing Agent. The only problem with this is that the box I received has no instructions inside.

The outside of the box simply says ''5 packets each to make 1 1/4 US gallons of solution (4.7 litres)''. I assume that one would mix a packet into 4 litres of water at about 40C and then add in 0.7 litres to finish. Do I have it right?

As for use, if I understand correctly, it's one part stock to four parts water, yes?

Any other special things to know when using Hypo Clearing Agent? Is it advised for film as well as FB paper?

Thank you,
Kent

[shyguy]

it's very straight forward, use warm water, say 3000 ml, dissolve the powder in it then add the balance of the liquid. done

S.

[Tom Hoskinson]

Hi All,

Any other special things to know when using Hypo Clearing Agent? Is it advised for film as well as FB paper?

Thank you,
Kent

The primary ingredient in Kodak HCA is sodium sulfite. Check out the APUG Chemistry Recipes.

HCA is not really necessary for washing the fixer out of film but it does aid in the removal of sensitizing dye residues.

HCA is very useful in washing fixer residues out of fiber based paper.

[srs5694]

A year or so ago, a friend gave me a box of old photochemistry he had dug out of a high-school darkroom. In that box was an ancient box of Kodak Hypo Clearing Agent.

The outside of the box simply says ''5 packets each to make 1 1/4 US gallons of solution (4.7 litres)''. I assume that one would mix a packet into 4 litres of water at about 40C and then add in 0.7 litres to finish. Do I have it right?

Almost; you'd mix a packet into 4 liters of water and then add water to bring the total volume up to 4.7 liters. The amount you add will be slightly less than 0.7 liters. In practice, I doubt if adding 0.7 liters (resulting in slightly more than 4.7 liters of solution) would make much difference, though.

As for use, if I understand correctly, it's one part stock to four parts water, yes?

That's what it is for modern Kodak HCA. I don't know if Kodak ever marketed anything that required a different dilution.

Is it advised for film as well as FB paper?

I use it for film only. (I've not yet tried FB paper, just RC paper.) It's not strictly necessary, but it cuts down on water requirements and time spent washing the film.

[Jennifer]

Hi,
Don't mix it it to 1.25 gallons. The 1.25 is total WORKING solution it will make. They still sell that size. I have the 5 gallon size which is mixed to a total of ONE gallon STOCK solution. HCA is diluted 1:4 right before use.
Check the kodak web site, but it should be mixed to a total of 946ml stock solution. Kodak says diluted only keeps 24hrs. Stock in full bottle is listed 3 months keeping time.

Jennifer

[Tom Hoskinson]

...Hi, Kodak says diluted only keeps 24hrs. Stock in full bottle is listed 3 months keeping time.

Jennifer

The version of washing aid (HCA) that is buffered with sodium bisulfite will keep much longer than 24 hours. See the recipes in the APUG Chemical Recipes.

I mix it as a one shot just before using: 20 to 30 grams of sodium sulfite per liter of water. If your water is hard, add a pinch of sodium citrate.

[Max Power]

You bunch really are brilliant!

Thanks everyone for your help; it is greatly appreciated.

Kent