Archival Insurance.

You'll have probably seen those old faded and yellowing photographs in the family album? Any you realize that your pictures won't last forever... but wait, there's things you can do to maintain your art for generations. And one of the most important is to remove those chemicals from the film and paper emulsion before they ruin your image. Let's see how...

If you want archival film or paper washes you need to remove ALL the thiosulphate fixer (sometimes known as hypo) from the emulsion. There’s a way to test for this. Use a Hypo test.

Hypo test

Stock solution:
Distilled water  1 liter
Potassium Permanganate  1.0g
Sodium Carbonate (anhyd)  1.0g

Place a few milliliters of your print or negative wash water in a clear jug and an equal amount of distilled water in another clear jug.  Now add one drop of the above formula into each of these jugs and watch how the color clears from both. It should be at the same rate. If the negative or print wash water clears first there is still residual Hypo in the water.  Wash film or paper for longer and retest.