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Process control parameters

Film Process

Dmb-Yb

Retained silver

Indicates if silver has not been bleached out of the film.
If the reading is high it indicates presence of silver. There is no lower limit for this parameter
Causes: Under-active bleach.

HD-LD

HD-LD

Also called "Contrast". If too low, indicates low contrast. It is rarely too high.
Causes: blocked filters or recirculation pump failure.

LD

LD

Low Density or "Speed". Indicates the process activity.
If too high indicates high developer replenishment rate or temperature
If too low, indicates low developer replenishment rate or temperature.

D-Min

DMin

The minimum density in the film. This can be influenced by all process steps: Over-active developer, under-active bleach or fixer or dirty stabilizer or wash.
Occcasionally a condition called bleach stain occurs which raises the green and/or blue plot.

Paper Process

Yellow patch

The yellow patch indicates adequate bleach-fix performance. Retained silver, the result of weak bleaching, makes the patch looks gray and muddy. This parameter is plotted for some control strip formats.

Black

The maximum density: There is usually no upper limit as the paper's maximum density cannot be exceeded.
Causes of low black: Under-active developer.

HD-LD

Also called "Contrast". If too low, indicates low contrast. It is rarely too high.
Causes: blocked filters or recirculation pump failure.

LD

Low Density or "Speed". Indicates the process activity.
If too high indicates high developer replenishment rate or temperature
If too low, indicates low developer replenishment rate or temperature.

Stain

The minimum density in the paper. This can be influenced by all steps. Over-active developer, oxidised bleach/fix or dirty stabilizer or wash.