Fixer Testing & Rotation Log

Two-Bath System Overview

FIRST BATH (older)          SECOND BATH (fresher)
━━━━━━━━━━━━━━━━━━          ━━━━━━━━━━━━━━━━━━━━━
Film/prints enter here  →   Ensures complete fixing
Brief fix time              Full fix time
Accumulates silver          Stays relatively clean

When first bath exhausts:
1. Silver recovery from first bath
2. Discard first bath
3. Promote second → first
4. Make fresh second bath

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Current Bath Status

Bath	Date Mixed	Fixer Type	Dilution	Capacity Target
FIRST	__________	__________	________	________ rolls/prints
SECOND	__________	__________	________	________ rolls/prints

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Testing Log

Test fixer before each session or every 10 rolls/20 prints minimum.

Testing method: ☐ Hypo check solution ☐ Silver test strips ☐ Film leader clearing time

Date	Bath	Test Result	Rolls/Prints Since Mixed	Action Taken
	☐ 1st ☐ 2nd	☐ Good ☐ Marginal ☐ Exhausted
	☐ 1st ☐ 2nd	☐ Good ☐ Marginal ☐ Exhausted
	☐ 1st ☐ 2nd	☐ Good ☐ Marginal ☐ Exhausted
	☐ 1st ☐ 2nd	☐ Good ☐ Marginal ☐ Exhausted
	☐ 1st ☐ 2nd	☐ Good ☐ Marginal ☐ Exhausted
	☐ 1st ☐ 2nd	☐ Good ☐ Marginal ☐ Exhausted
	☐ 1st ☐ 2nd	☐ Good ☐ Marginal ☐ Exhausted
	☐ 1st ☐ 2nd	☐ Good ☐ Marginal ☐ Exhausted
	☐ 1st ☐ 2nd	☐ Good ☐ Marginal ☐ Exhausted
	☐ 1st ☐ 2nd	☐ Good ☐ Marginal ☐ Exhausted

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Processing Log

Date	Material	Quantity	Bath 1 Time	Bath 2 Time	Notes
	☐ Film ☐ RC ☐ FB
	☐ Film ☐ RC ☐ FB
	☐ Film ☐ RC ☐ FB
	☐ Film ☐ RC ☐ FB
	☐ Film ☐ RC ☐ FB
	☐ Film ☐ RC ☐ FB
	☐ Film ☐ RC ☐ FB
	☐ Film ☐ RC ☐ FB
	☐ Film ☐ RC ☐ FB
	☐ Film ☐ RC ☐ FB
	☐ Film ☐ RC ☐ FB
	☐ Film ☐ RC ☐ FB

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Bath Rotation History

Date	Action	First Bath Disposed	Silver Recovery?	Notes
	☐ Rotation ☐ Full refresh	☐ Yes ☐ No	☐ Yes ☐ No
	☐ Rotation ☐ Full refresh	☐ Yes ☐ No	☐ Yes ☐ No
	☐ Rotation ☐ Full refresh	☐ Yes ☐ No	☐ Yes ☐ No
	☐ Rotation ☐ Full refresh	☐ Yes ☐ No	☐ Yes ☐ No
	☐ Rotation ☐ Full refresh	☐ Yes ☐ No	☐ Yes ☐ No

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Testing Guide

Hypo Check Solution (Potassium Iodide)

Add 2–3 drops to small sample of fixer:

Result	Meaning	Action
Clear/light yellow	Fresh, low silver	Continue using
Slight cloudiness	Moderate silver	Monitor closely
Milky precipitate	High silver, near exhaustion	Rotate baths

Film Leader Clearing Test

Drop unexposed film leader into fixer, time until clear:

Clearing Time	Fixer Status	Action
< 2× normal	Good	Continue using
2–3× normal	Marginal	Test more frequently
> 3× normal	Exhausted	Rotate baths

Normal clearing time for rapid fixer: 30–60 seconds

Silver Test Strips

Follow manufacturer instructions. Generally:

• Compare to colour chart
• Note silver concentration in mg/L
• Rotate when first bath exceeds ~5,000 mg/L

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Typical Capacity (Rapid Fixer)

These are estimates—always verify by testing.

Material	First Bath	Second Bath	Total System
35mm film (36 exp)	20–30 rolls	40–60 rolls	60–90 rolls
120 film	15–20 rolls	30–40 rolls	45–60 rolls
8×10 RC paper	40–60 prints	80–120 prints	120–180 prints
8×10 FB paper	30–40 prints	60–80 prints	90–120 prints

Higher silver content materials (fast films, FB paper) exhaust fixer faster

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Fix Times (Rapid Fixer)

Material	First Bath	Second Bath
Most B&W films	30–60 sec	2–4 min
T-grain films (T-Max, Delta)	60 sec	3–5 min
RC paper	30 sec	1 min
FB paper	30–60 sec	2–3 min

First bath time is brief—just to begin the process. Second bath does complete fixing.

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Notes

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Sustainable Darkroom series