After photographic exposure, photographic film and paper are chemically processed to create either a positive or negative picture. This process is known as photographic processing. The latent picture is permanently changed into a visible image by photographic processing, which also makes it light-insensitive.
Read More: Film processing
Regardless of the producer of the film or paper, all procedures based on the gelatin-silver process are comparable. Thermally produced films and instant films like Polaroid are examples of exceptional variations. Kodak’s exclusive K-14 process was necessary for Kodachrome. Production of Kodachrome film was discontinued in 2009, and as of December 30, 2010, K-14 processing was no longer accessible. Materials made with ilfochrome employ the dye destruction method.
Important phases in the creation of Ag-based photos. A latent picture is created (step 1) when light (hv) impinges on one of the two silver halide particles. Using photographic develops, the latent image is enhanced and the silver halide crystal is transformed into an opaque silver metal particle (step 2). Step 3 involves fixing to eliminate any leftover silver halide.
Every film and piece of paper is processed in a sequence of chemical baths that are constantly watched over and kept at a certain temperature and treatment interval. Other baths are less susceptible to changes in treatment duration and temperature than developer baths, which are most sensitive to them.
Processing of negatives in black and white
To help the subsequent chemical treatments work more easily, the film can be soaked in water to increase the size of the gelatin layer.
The latent picture is transformed by the developer into large metallic silver particles.
A stop bath stops the developer’s action; this is usually a diluted solution of citric or acetic acid. You might use a cleanwater rinse in its place.
The fixer dissolves any residual silver halide, making the picture permanent and resistant to light. Ammonium thiosulfate, or hypo, is a common fixer.
Any leftover fixer is eliminated by washing in fresh water. The silver image may erode from residual fixer, resulting in fading, discoloration, and staining.
If a hypo cleaning agent is applied after the fixer, the washing time can be decreased and the fixer more thoroughly removed.
To help ensure uniform drying and get rid of drying marks from hard water, film can be washed in a diluted solution of a non-ionic wetting agent. (If the final rinse wetting ingredient causes leftover ionic calcium on the film to slip out of solution, creating spots on the negative.) with exceptionally hard water locations, a pre-rinse with distilled water may be necessary.
After drying in a dust-free atmosphere, the film is cut and inserted into protective sleeves.
The film is referred to as a negative once it has been developed. It is now possible to print from the negative by putting it in an enlarger and projecting it onto a piece of photographic paper. The expansion process can include a wide range of methods. The expansion strategies of avoiding and burning are two instances.
Alternately (or additionally), the negative may be digitized after modification, retouching, and/or editing for digital printing or web viewing.
Mechanical squeegees or pinching rollers take the role of the stop bath in contemporary automated processing equipment. Much of the leftover alkaline developer is eliminated by these processes, and the acid, when applied, neutralizes the alkalinity to lessen the developer’s contamination of the fixing bath.
Processing for reversing black and white
There are three more steps in this process:
The produced negative image is removed from the film by bleaching it after the stop bath. Next, a latent positive picture made of undeveloped and unexposed silver halide salts may be seen in the film.
Either chemically or by exposure to light, the film becomes fogged.
The second developer is used to develop the residual silver halide salts, turning them into a positive picture.
The film is then corrected, cleaned, dried, and cut.
Color manipulation
Dye couplers are used by chromogenic materials to create color pictures. The C-41 technique is used to develop color negative film, while the RA-4 process is used to create color negative print materials. Although there are variations in the initial chemical developer, all procedures are quite similar.
The steps involved in the C-41 and RA-4 procedures are as follows:
The silver negative picture is developed by the color developer, and the dye couplers in each emulsion layer are activated by byproducts to generate the color dyes.
The produced silver picture is changed into silver halides using a rehalogenizing bleach.
Removes the silver salts with a fixer.
The film is trimmed, dried, stabilized, and cleaned.
Commercial handling
In commercial processing, the film is fed into the processing equipment automatically or by an operator handling the film in a light-proof bag. Films are often spliced together in a continuous line and the processing equipment is operated continuously. One processing equipment, with autonomously regulated temperature, time, and solution replenishment rate, performs all the processing processes. The film or prints come out clean, dry, and prepared for manual cutting. Additionally, some contemporary equipment automatically cut films and prints. This can occasionally lead to negatives being cut across the middle of the frame in situations when the frame edge is blurry or the gap between frames is extremely tiny, as in low light photography.
What kinds of photographic film processing are there?
In film photography, there are three typical kinds of developing procedures. These are C-41, E-6, and B&W, which stand for the three primary film types: black and white, color positive (also known as slide film or color reversal), and color negative.
The majority of color films are developed using the most popular method, C-41. The colors are inverted on the film because it creates negative pictures. On the negative, the darkest areas will seem bright, and vice versa. Kodak first launched C-41 in 1972. The same process is also known by a number of other, less common names, such as CN-16 by Fuji, CNK-4 by Konica, and AP-70 by AGFA. The majority of laboratories can develop color negative film fast and affordably.
Color positive film, also referred to as reverse or slide film, is developed using the E-6 method. Despite producing color pictures similarly to C-41, the outcomes varied greatly because of the distinct chemical reactions. These days, it’s a less popular procedure that not all laboratories provide.
As its name implies, the black and white technique is the method used to create black and white movies. It generates negative pictures, just as C-41. B&W is by far the easiest of these three primary processing methods, making it a popular option for anybody starting to self-develop at home.
Cross-processing, or using the incorrect type of processing for the film you use (e.g., developing color negative film in E-6 chemicals), is a common experimental method in the Lomography community because of the unexpected and fascinating results it may yield.
