The paper developer used in most labs is called Dektol.  It is made by Kodak.  This developer will mix 50-50 or equal parts of water and stock solution.  We usually use 10 oz of Dektol and 10 oz of water when we mix.  The chemicals can absorb into the plastic of the mixing container so they should be rinsed thoroughly when finished. 

One of the more popular film developers is Kodak HC-110.  This comes in as a thick liquid.  The liquid is pored into a half full bottle of room temperature water.  Water is poured into the HC110 bottle that the thick concentrate just came from.  The bottle is shaken vigerously and the resulting clean up mixture is added to the main bottle of developer.  Additional water to make a gallon is added and the mixture shaken vigerously.  When used this developer is diluted 8:1 or. We use one and one half ounce with 10 oz of water to make a total of 11 to 12 oz of mixture for processing.  The powder used to mix the Dektol is harmful to the lungs in large quantities so a photographer needs to mix it slowly so that little powder splashes up in the air.  When used in a dilution like this the original bottle is called a "stock" solution.  NEVER pour  anything into the stock bottle. Even a small amount of chemical in the bottom of the mixing container could destroy or KILL the entire stock solution.

The ideal temperature for photography is 68 degrees.  When the temperature is hotter the chemicals work faster, but sometime too fast causing lower contrast.  If film or photo paper is not left in the developer long enought it will not allow all of the possible silver to be created resulting in a light negative or low contrast print.  The photographer must be careful to keep the temperature between 60 and 75 degrees and to adjust the time of development to keep the contrast good.   Once the thermometer has been placed in a solution it is important to rinse it off after to avoid contamination.  CONTAMINATION is the biggest problem in the new photo students darkroom.  It can destroy a roll of film, lower contrast and make poor results.

Specialty developers exist that allow the film to respond to a lower light level and thus increasing its ASA.  These films often trade off a lower contrast in the finished print.  Other developers with a great deal of water in their dilution and special chemicals added to them allow the photographer to be way off in exposure and still get a good range of black and white shades on the finished print. 

The other chemical used often is called STOP BATH.  This is acetic acid which is found in orange juice.  This acid usually has a colored indicator dye placed in it that is yellow when the acid is strong and useful and purple when exhaused and no good.  In our lab for most classes we use just plain water to rinse off the developer for either film or paper.  The stop bath or rinse is needed to remove the developer from the film or paper and keep it from wearing out the fixer as fast.  It will allow more pictures to be processed in our chemicals.  The Stop Bath is mixed from a strong concentrate that is ALWAYS added to a full container of water.  Never pour a small amount of water into a strong acid as it can create air pollution and can splash in the eyes.   For most of our work at Santa Cruz High we will not use real stop bath but will replace it with a good rinse of water.

The last chemical we use is called FIXER.  This is sodium thiosulphate in chemical terms.  This chemical can react with developer to create AMMONIA which can cause a major smell in the darkroom.  This chemical when spilled on the floor will create a white stain. The powder that is created on this stain can float into the air and create a smell in the air.  The solution to this pollution problem is to rinse fixer off of paper or film before moving it around in the lab or room.  At the end of every class or lab use the photographer should rinse down the sink and counter top.  The fixer does not react with air like the developer does so it can be left in the sink tray for a few days at a time.  The fixer is not thrown out after being used for film or paper.....it can be used over and over until it is exhausted.  The lab technician will test it with a test kit to know when to throw it out.

In the darkroom a photographer may use print tongs to pick up paper in the developer trays.  One tong should be used in the developer and a second tong used in the stop bath and fixer.  NEVER put a tong or hand that has been in fixer back into the developer because the fixer will neutralize the developer. 

A darkroom needs to be kept dry on the counter top and your hands need to be dry when touching photo paper.  IF you touch photo paper with wet hands you might get a white spot or finger prints on the print.  Spills on the counter top can cause spots on your finished print.  Chemicals spilled on the floor or counter can also get on clothes and cause stains.  Developer on clothes will make a dark brown stain if not washed away with COLD water in 24 hours before it crystalizes.  Developer or fixer on your hands is usually not a problem except to the very sensitive skinned person.  Exposure to developer and fixer for just a few hours a day has not long term health effects.  However, the chemical can cause nausia and stomach problems if you get it in your mouth by putting your hands in your mouth.  Photographers should wash their hands with soap and water after working in the lab before eating food.