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AnalogFixerDarkroom chemistry for black-and-white film
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Developer and fixer chemistry

What the agents in a developing and a fixing bath do, what each manufacturer specifies for them, and what to make of it when two sheets for the same task disagree.

In this section

  • AJ-3 names Rapid Fixer film 1:3 and paper 1:7 — E-103CF’s Rapid row does not

    Shows that Kodak AJ-3 (February 2016) publishes “Dilute 1:3 for film and 1:7 for paper” for Rapid Fixer (and the same pair for KODAFIX), while E-103CF (© 2010) gives Rapid Fixer’s typical dilution only as “1:3 plus Part B (hardener)” with no paper fork in that cell or in the Rapid description block; that E-103CF’s KODAFIX description carries the film/paper split the Rapid block lacks; and that the Kodak Rapid Fixer pack-in (© Kodak 2015, code 20370811) separates film and paper preparation charts in which the paper chart lists half the Solution A — and half the Solution B — of the films-and-plates chart at the same final volume, the arithmetic of 1:7 versus 1:3 for Solution A, without printing AJ-3’s 1:7 label.

  • Hypam’s hardener doubles film fixing time — and discourages its own use

    Sets Ilford Rapid Fixer’s absolute hardener ban beside Hypam’s optional hardener path in the August 2002 Hypam fact sheet, shows that the same Hypam sheet doubles average minimum film fixing time at 20°C from 2–5 to 4–10 minutes when hardener is used and states that higher hardener doses reduce fixing and washing efficiency, and records that Multigrade FB Classic (October 2013) independently rejects hardening fixers for paper because they reduce washing efficiency while naming both Rapid Fixer and Hypam as non-hardening products.

  • ILFOSTOP PRO is specified on fixer sheets — Chemical Sundries does not document it

    Shows that Ilford Rapid Fixer (July 2010; same structure in August 2002) and Hypam (August 2002) embed an ILFOSTOP / ILFOSTOP PRO stop-bath pair, publish different unreplenished capacities for the two products, and state that “ILFOSTOP PRO is recommended for all machine processing applications,” while the December 2017 Chemical Sundries sheet that is Ilford’s dedicated stop / wetting / washaid product document lists only ILFOSTOP, ILFOTOL and Washaid, publishes the ILFOSTOP capacities that match the fixer-sheet ILFOSTOP column, and says ILFOSTOP “is not recommended for machine processing applications” because of residual dye-stain risk — without naming or tabulating ILFOSTOP PRO; that the March 2002 2000RT machine-chemistry sheet tabulates only ILFOSTOP PRO (temperature band 20–40°C, RC capacity 90 sheets/litre); and that Multigrade FB Classic (October 2013) names only ILFOSTOP in its dish/tray processing summary.

  • What fixer exhaustion actually means

    Shows that the 40-print capacity figure on Ilford's own fixer sheets is identical to the commercial-permanence limit printed two pages later, so following it gives four times the silver the same document allows for archival work; reconciles the differing silver thresholds Ilford publishes across its product sheets; separates the three darkroom tests that community advice routinely conflates; and replaces "archival" with the two standards that actually apply — ISO 18901 for film and ISO 18929 for prints — showing that what fixing and washing control is residual thiosulfate in the material, not silver concentration in the bath.

  • “Stop bath or running water” is not one manufacturer rule

    Separates four published stop-step framings the field collapses into one phrase: Kodak F-4016 for T-MAX 100 (June 2018) and F-4043 for T-MAX 400 (February 2016) equate Indicator Stop Bath with running water at 30 seconds; Kodak ED-BWF (March 2023) names only Indicator Stop Bath at 1:63 for the rinse/stop row; Kodak E-103CF (2010) tabulates Indicator Stop Bath at 1:63 for 30 seconds at 65–70°F with discard on purplish/blue and no water alternative; Kodak AJ-3 (February 2016) lists “stop bath or water” in film materials while its Stop Baths appendix says you need Indicator Stop Bath (1:63); and Ilford’s December 2017 Chemical Sundries sheet specifies ILFOSTOP at 1+19 for 10 seconds while framing a water bath as an occasional substitute that increases mark and stain risk.

  • Kodak names Rapid Fixer Solution B a hardener on E-103CF — not on the pack-in

    Shows that Kodak E-103CF (© 2010) labels Rapid Fixer a “fast-acting hardening fixer” whose Solution B is “the hardener concentrate” and whose typical- dilution cell reads “1:3 plus Part B (hardener),” while the Kodak Rapid Fixer pack-in (© Kodak 2015, code 20370811) publishes Solution A/B preparation charts for film and paper without using the words hardener or hardening and isolates Solution B as omit-able only in the Dektomatic note; set beside Ilford Rapid Fixer’s hardener ban and Multigrade FB Classic’s rejection of hardening fixers for paper, so the Kodak A+B bath is not the same published kind of claim as Ilford’s non-hardening Rapid path.

  • Kodak’s one-bath paper times are not Ilford’s average minima

    Shows that the Kodak Rapid Fixer pack-in (© Kodak 2015, code 20370811) publishes tray fixing times at 18–24°C of 2 minutes (one-bath) / 1 minute per bath (two-bath) for resin-coated paper and 10 minutes (one-bath) / 2:30–5 minutes per bath (two-bath) for most non-resin-coated papers, with an explicit do-not-exceed note; that Ilford Rapid Fixer (July 2010) and Hypam (August 2002) publish average minimum paper times at 20°C of ½ minute RC / 1 minute FB at 1+4 and 1 minute RC / 2 minutes FB at 1+9; that Multigrade FB Classic (October 2013) restates the FB 1+4 path as 1:00; and that AJ-3’s resin-coated tray procedure (February 2016) uses 2 minutes — matching Kodak’s RC one-bath figure, not Ilford’s half-minute RC row — while film bands on the same Kodak pack-in (2–4 / 3–5 minutes) overlap Ilford’s general-purpose film band (2–5 minutes at 1+4).

  • “Twice the clearing time” names three published rules

    Separates three manufacturer rules that the field collapses into one phrase: Ilford Rapid Fixer (July 2010) and Hypam (August 2002) each publish a drop-test fixing-time rule (remain in fixer for twice the clearing time) and a separate discard rule (discard when used clearing exceeds twice fresh clearing); Kodak F-4016 for T-MAX 100 (June 2018) attaches “twice the time it takes for the film to clear” to non-Rapid fixers while giving Rapid Fixer an absolute 3–5 minute band and a mid-fix clearing check after three minutes; and Kodak ED-BWF (March 2023) and J-109 (February 2018) restate a generic twice-clearing instruction without Ilford’s drop-test method or discard threshold.

  • Ilford’s manual 1+9 is a paper clause, not a film path

    Shows that Ilford Rapid Fixer (July 2010; same structure in August 2002) and Hypam (August 2002) each publish a categorical film dilution sentence — “for all film fixing applications … diluted 1+4” — and place the optional 1+9 wording only inside the following paper-machine paragraph (“for manual fixing applications it can be diluted either 1+4 or 1+9”); that the fixing- time, capacity and replenishment tables populate film only at 1+4 while paper rows carry both dilutions with doubled paper times at 1+9 and the same published capacity per litre of working strength; and that Multigrade FB Classic (October 2013) independently cites Rapid Fixer or Hypam at 1+4 for one minute, not the 1+9 paper path.