RP01 - Sodium Thiosulfate

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).

RP02 - Sodium Bisulfite

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).

RP03 - Potassium Oxalate

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).

RP04 - Potassium Ferricyanide

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).

RP05 - Potassium Bromide

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).

RP06 - Oxalic Acid

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).

RP07 - Ferric Ammonium Citrate

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).

RP08 - EDTA Tetra Sodium

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).

RP09 - Copper (I) Chloride

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).

RP10 - Copper (II) Chloride

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).

RP11 - Citric Acid

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).

RP12 - Potassium Aluminum Sulfate

    • Can replace acetic or citric acid in a pinch.

    • Instantly halts development by dropping pH.

    • Why use it? No vinegar smell; easy to measure.

    • Handy for bringing developers, fixers, or toners back into spec if they drift alkaline.

    • Useful in experimental/alt-process setups where precise acidity matters.

    • Some fixer formulas benefit from extra acidity to improve stability or working life.

    • More common in custom-mixed or older recipes.

    • Employed in niche recipes where a strong, dry acid is preferred (e.g., certain pre-acid baths).