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Film and Paper:

Emulsion: Layer of photosensitive substance coated on the base material.

Colour coupler: A substance that will show up colour on reacting with developer.

Dye: The colour formation substance in the emulsion.

Base: The carrier of the photosensitive material.

Latent image: An invisible image formed by light in the emulsion after exposure.

Reciprocity failure: A region on the characteristic pattern of the photosensitive material; at which it fails to produce a response proportionally.

Fog: Unwanted colours, which can make image, look misty


Developer: A chemical process to bring out an image.

Bleach: A chemical process to remove excessive silver caused by the developer.

Fix: A chemical process to dissolve silver halide crystal left over by developing.

Wash: A process to remove chemical left in the emulsion.

Stabilize: A chemical process to prevent bacteria growth, and colour fade out on the media.

Starter: A pre-seasoning chemistry applied to newly mixed chemistry.

Developing Agent: A chemical, which perform the reduction of silver and bring out colour as well if it is a colour: developing agent.

Anti-oxidant: A chemical use for preventing another chemical from turning bad through oxidation.

Anti-fog: A chemical, which can reduce the misty looking on image, caused by fog.

Water softener: A chemical, which can reduce the hardness of water caused by mineral salt.

Alkaline: A chemical, which controls the PH of developer within its operating range.

Acid: A chemical, which controls the PH of bleach, fix within its operating range.

Replenisher: A chemistry use to recover the lost of working solution through use.

Working solution: A chemistry that actually performs the processing.

Season: Aging of chemistry through use.

PH: A mean of measuring the alkaline or acidic property of solution.

Reduction: A chemical reaction, which can transform the silver halide into metallic silver.

Oxidation in developer: Developing agent attacked by oxygen, making it turns bad.

Oxidation in bleach: A chemical reaction, which can reverse the metal silver back into silver halide.

Tar: A black waste product generated by carry over of developer into bleach, which can stain picture.

Machine design:

Working tank: The chemical tank where actual processing occurs.

Replenishment tank: Container where chemicals are stored before it will be pumped into the working tank to refill the consumption or losses during processing.

Roller transport: A kind of processing machine design, which is utilizing lots of rollers to transport the material.

Roller transport with track: A kind of processing machine design, which uses both rollers and tracks to transport the material. This kind of design can reduce numbers of rollers.

Dip and Dunk: A kind of processing machine design, which dips the photo material into the working tank.

Printer: The machine where paper is exposed.

Rack: The roller mechanism where paper transport through.

Squeegee: A cleaning device in the form of roller or blade use to remove excessive chemistry to prevent carry over.

Stocker: A storage chamber, which holds the exposed paper, waiting for a batch processing

Cutter: A device used for cutting photo from a long strip.

Sorter: A device used to sort different order to photo.

Colour Balance:

Cut off filter: Light filters, which throw in during exposure period to stop a primary colour light passes through.

Dichroic filter: A kind of filter system to adjust the quality of light.

Ring around: A kind of printer calibration method by printing multiple prints of different colour settings, and selecting the best one. The procedure will be repeated until the colour is obtained.

Neutral Density: Does not has any colour contents. It can only affect the density.

Gray card: Cardboard, which has 18% light reflection gray colour.

Control negative: A negative made with specific type of film for calibrating printer.

Bull's eye: Nickname of control negative.

Density: The darkness of colour.

Colour Failure: The unfaithful reproduction of colour.

Negative Colours: The three primary colours when evenly mixed produce black colour. They are yellow, magenta and cyan.

Positive Colours: The three primary colours when evenly mixed can produce white colour. They are blue, green, and red.

Opposite colour: The colour, which is opposite to each other. For example, yellow and blue, magenta and green, cyan and red.

Contrast: A comparison between brightness and darkness.

Quality control:

Transmissive densitometer: An instrument use to measure the density and quality transparency.

Reflective densitometer: An instrument, use to measure the density and quality of paper.

Control strip: A precisely exposed film or paper, use for testing the quality of chemistry.

Replenishment rate: A numerical figure to indicate the amount of chemical required refilling the consumption or losses per unit area of the photosensitive material.

Overflow: The excessive solution that is flow out of the working tank; in order to keep in level.

Carry over: The carrying of chemical from one processing tank to another processing tank by the material to be processed.

Turn over: The mathematical assumption that old chemistry in a processing tank has been replaced by new chemistry.

Top up: Addition of water to recover the lost through vaporization.


Wallet: The inside envelope, use to contain photo.

Envelope: The outside envelope, use to collect job.

Negative sleevings: A plastic bag with continues section for storage of negatives.

Perforated: A design feature to make it easy to tear.

Non perforated: A design feature requires a cutter to separate it.

Hi-Tech Photographic Chemistry
5143 Tomken Road, Mississauga, Ontario L4W 1P1, Canada.
( 905-625-9261