Practice question · Numerical answer
Washing fibre-base paper takes about 60 minutes in running water, or about 10 minutes after a hypo-clearing bath. By what factor is the washing time reduced?
Hints
- Divide the longer time by the shorter.
- 60 divided by 10.
Show the answer
6
Why
Six times. The same factor applies to the water consumed, since the flow rate does not change. Hypo clearing works because sodium sulfite converts the residual thiosulfate into compounds far more soluble than the ones the fixer leaves behind, chemistry doing what fifty extra minutes of water cannot.
Practise Archival Processing and Permanence
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