Tools and directories

The check, at the tray and at the bottle

Updated October 2026

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One: have you made the determination, at the point of generation?Two: by knowledge or by test, and is it written down?And check the exclusions first Three: where is the spent fixer going?Four: are your developer bottles small and full?And which label does the product carry?Re-determine when the darkroom changes Two of the four happen before anything reaches a drain References

Four questions. Two are about the waste and they come first.

One: have you made the determination, at the point of generation?

Before any dilution, mixing or other alteration. For spent fixer that means as it leaves the process, into its own container, not after it has joined wash water in a carboy.

Two: by knowledge or by test, and is it written down?

Knowledge of the waste is permitted and the rule names what counts: origin, composition, the process producing it, feedstock. Whichever route, record it with the reasoning or the result and the date.

And check the exclusions first

The sequence is whether the waste is excluded from regulation, then whether it is listed, then whether it exhibits a characteristic. A record that starts at the characteristic has skipped two steps.

Three: where is the spent fixer going?

A silver recovery service or a hazardous waste contractor, and the container is usually theirs to specify. Local sewer pretreatment rules are separate from RCRA and can be stricter, so a drain is not an assumption.

Four: are your developer bottles small and full?

Because oxidation is the product-side failure and headspace is the cause. 132 of the 191 containers here are at or under 500 mL, and filling to the neck with a date on the label is the whole practice.

And which label does the product carry?

The six hazard communication elements for a workplace shipment, or the consumer labeling route if it is sold as a consumer product subject to those rules. Hazard communication expressly steps aside for the waste.

Re-determine when the darkroom changes

A new chemistry, a different film, a change in throughput or in how long fixer is used before replacement. The rule requires a determination again when the properties may have changed, and a darkroom changes quietly.

Two of the four happen before anything reaches a drain

Which is why they are first. The product-side questions can be revisited at any time, and a determination that should have been made at the point of generation cannot be made retrospectively.

References

40 CFR 262.11, Hazardous waste determination and recordkeeping. The determination must be made at the point of waste generation, before any dilution, mixing or other alteration occurs, and again if the properties change; and it may be made using knowledge of the waste including its origin, composition, the process producing it and the feedstock. law.cornell.edu

40 CFR 261.24, the Toxicity characteristic. A solid waste exhibits it where the Toxicity Characteristic Leaching Procedure extract contains a Table 1 contaminant at or above the listed level, and where the waste contains less than 0.5 percent filterable solids the waste itself is considered to be the extract. Table 1 lists D011 Silver at 5.0 mg/L. law.cornell.edu

40 CFR 261.4, the exclusions from the definition of solid and hazardous waste, which 40 CFR 262.11(b) requires a generator to check before going on to the listing and characteristic questions. law.cornell.edu

29 CFR 1910.1200, Hazard Communication, which sets the six label elements for a shipped container of a hazardous chemical and the sixteen-section safety data sheet. Note that 1910.1200(b)(6)(i) excludes hazardous waste subject to EPA regulation under RCRA, so the product and the waste are under different regimes. law.cornell.edu

Written from federal regulation and from measured catalog data, not from a darkroom. Hazardous waste regulation is federal with authorized state programs on top, and many states and municipalities regulate silver discharge to sewer separately. The determination for a specific waste is the generator’s to make.