Cleaning Equipment and Disposing of Spent Chemicals
A well-prepared chemistry can be undone by poorly cleaned equipment, just as responsible photographic practice cannot disregard the correct disposal of spent baths. This guide closes our series by addressing these two aspects, often overlooked yet of an importance equal to that of development itself.
In darkroom practice, one is accustomed to placing every care in the preparation of chemicals and the observance of times, at times neglecting an aspect intimately connected to these: the cleanliness of the equipment with which the chemicals themselves are handled. A bath prepared with every scruple may see its efficacy undone if poured into a vessel bearing, invisible to the eye, a residue of the previous bath.
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Equipment
Good laboratory practice holds that each bath — developer, stop, fixer — should have its own dedicated instrument: jug, funnel, thermometer, tank. Where this is not possible for want of means, it is recommended at the very least to affix to each instrument a label declaring its exclusive use, so as to avoid a residue of developer contaminating the fixer, or vice versa, with consequences sometimes manifest, sometimes subtle and difficult to trace.
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Glassware and Bottles
The optimal condition for cleaning bottles and glassware is steam washing, which ensures the removal of every residue even from the least accessible recesses. Where this means is unavailable, a thorough rinse with running water constitutes sufficient practice for everyday use.
There is, however, one case in which no rinse, however thorough, may be called sufficient: that of accordion-style bottles. Their construction, folding upon itself, conceals recesses and creases within which chemical residue lodges in a manner nearly unreachable, whatever care be taken in rinsing. They are, for this reason, the most frequent cause of developers that prove inexplicably ineffective, or that produce inconsistent results from one session to the next, without the operator managing to trace the cause to the chemistry itself, rather than to the vessel containing it. We therefore recommend avoiding their use for storing photographic chemicals, favouring instead bottles of rigid and regular form.
As a general rule, any bottle of which one cannot say with certainty that complete cleanliness has been achieved should without hesitation be discarded, rather than kept in doubt: the cost of a new bottle is a far lesser thing than the damage of a compromised development.
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⚠️ DISPOSAL OF SPENT CHEMICALS — read before proceeding
Spent photographic chemicals, whether developers, fixers, or other baths, are to be considered chemical waste in every respect.
Do not pour spent chemicals down household drains or sewers.
Dispose of spent chemicals in compliance with local regulations governing chemical waste. Contact your municipality or local recycling centre to learn the correct disposal procedure for your area.