Kodak Hypo Clearing Agent is a powder wash aid for film and paper, making 4 litres of stock solution.
What it is for
Residual fixer in the emulsion is the main reason old prints yellow and fade. Water alone will remove it, but slowly and at great cost in water; this displaces the thiosulphate chemically and cuts washing several times over. The maker names two benefits outright: better archival stability and no toner stains.
How to dilute it
The sachet makes 4 litres of stock, and that in turn up to 19 litres of working solution.
Storage
Sealed powder keeps for years; mixed solution keeps far less well, so mix what you will use. Dissolve at the stated temperature and in the stated order — getting the order of components wrong ruins a developer more reliably than any timing mistake.
How it compares
Essential for baryta paper, which washes stubbornly. For film and resin-coated paper it is not critical, though the water saving is noticeable.
