B/W Film Processing

t-photo.com "B/W Film Processing" Oct. 1, 2000

B/W Enlarging

Darkroom Equipment

The major procedures of film processing are developing and fixing. Developing is to convert the latent image into a 'silver' image. Fixing is to clear away all unexposed and undeveloped silver halide. All other steps are used to keep the best quality or to guarantee a clean negative without any chemical residue.

Preparation before processing:
1. Loading the exposed film to Processing Tank.
2. Prepare all chemicals, keep the developer temperature as decided. For diluted developer, it is easier to fix the temperature with cold or warm water.
3. Check the developing time and other procedures.

Full list of B/W film processing (beginners can omit No.3, 5 & 7, some films may not require pre-wet, i.e. No.1 Water bath)

Procedure	Time	Agitation
1. Water bath	2 to 3 minutes	After filling water, shake the tank several times
2. Developer	Check film & temperature*	After filling, put lid on and initiate inverted agitation three times, follow by once (three inverted agitations) every minute.
3. Stop Bath	30 sec.*	After filling, immediately perform one inverted agitation, and once every ten seconds afterward.
4. Fixer	5 to 10 minutes*	After filling, perform inverted agitation fifteen times, follow by three times every minute.
5. Hypo-clearing Agent	2 to 3 minutes	Shake slightly after filling, no more agition required.
6. Washing	About 15 to 30 minutes	One way is to use running water, with refilling a few times. Without running wateer, then fill up and agitate for 30 sec., let it stay for 30 sec., pour out and fill again, repeat the agitation for about ten times.
7. Wetting Agent	1 minute	Shake tank after filling, no subsequent agitation required.
8. Drying	About half to one hour.	Depending on environment, keep until completely dried.

*Basing on the information of developer and fixer. For developer, check the dilution, film and EI (Effective Index, e.g. the film TMY, ISO 400, has been exposed for 800, the developing time must be EI 800 in order to have the push processing to complete.).

Check developing time: B/W chemicals

Developer is used to convert the latent image into negative image. This is a chemical process to reduce the silver of exposed silver halide into chemical silver. Chemical silver is a physical state of silver that is black in color. With different density, the silver grains forms the gray tones from white to black. With electrolyte process, the chemical silver can return back to its original state, metallic silver. This is the principle of silver recovery process.

Undeveloped or unexposed silver halide may react to light or heat, so they must be cleared to avoid fogging etc.

Developing time will affect the final image, especially gradation and contrast. Worst of all, excess time will give a coarse grain image. That is why the developing time is the most important factor. To avoid timing error, we can start the timer just before the filling of developer and pour out the developer after time up. Otherwise if we start the timer after the filling of developer, then we have to pour out the developer before the end of time, about 15 to 20 seconds. We suggest the first one.

The Water Bath before developing is to soften the emulsion, allowing developer to enter the emulsion as soon as possible. The Stop Bath after developer is also an important procedure. Although developer has been poured out, yet there would remain a considerate quantity inside the emulsion, still performing its chemical reaction. It needs chemical to stop this kind of uneven developing which is harmful to the gradation and worst of all, it is not controlled by any means.

Throughout the film processing, there are lots of chemicals remained in the emulsion. It must be clean thoroughly to avoid unexpected chemical reaction in future. The action of Hypo Clearing Agent is to draw out all these chemicals in a fast way. Washing alone will require longer time and may not be completely safe.

Loading Steel Tank

Loading Plastic Tank

Film processing

Front Page

B/W Film Processing

B/W Enlarging

B/W Chemicals