An explanation of the emulsion process, from the chemical foundation to film and paper and how emulsion has been incorporated into newer photography techniques.
Photographic emulsion is a light-sensitive coating applied to substrates. When exposed to light, the emulsion changes, hardens, and then fixes an image onto a medium such as photographic paper. The ingredients in the emulsion can be one of several types of silver halides, which are grainy salts of varied size and type (depending on the type of photographic work being done). The silver halide salts are light-sensitive and rest in a gelatinous material; they are incorporated onto a variety of mediums such as paper, plastic, fabric, or glass. (Also, the emulsion process is a very popular means of creating the screen on a silkscreen press, which is used to apply the imprint on promotional products like custom shirts and personalized paper cubes).
So, would you like to know how the emulsion process works? There are various steps in the emulsion process and several ways to manipulate the process to affect certain photographic styles. For example, let's say that a black and white image is projected onto a medium like photographic paper. The paper would then be inserted into a developing chemical that reacts with the silver halide crystals or grains in the emulsion. The developer changes the silver halide crystals into certain degrees of darkness to form the image. The paper is then inserted into another chemical called a “stop” that halts the development process, preventing the silver halide crystals from becoming any darker and freezing the image.
After the stop, the paper still contains many grains of undeveloped silver halide salts that must be removed. The paper is inserted into a hypo, or wash, where the undeveloped salts are removed from the paper. At this point the paper with its image is ready to be hung to dry (and is now called a photograph).
Emulsions used to form color images have several layers of emulsion, with each layer reacting differently to light to form the various shades and hues evident in color photographs.
Glass was used to contain early emulsions. Good results were obtained but the image could quickly degrade or become damaged by environmental conditions; this is why the images in so many old photographs appear foggy or faint. With the advent of photographic technology in the late 1800s, the emulsion process became much more manageable and reliable. As a result of the improved emulsion process, more durable photographs could be made that were likely to withstand the passage of time.
George Eastman made the first camera in 1887, and the emulsion was layered onto a plastic-like material eventually known as 'film' and enclosed into a camera. After every time the camera had been used to take photographs, it had to be returned to Rochester, New York, where Eastman’s company would process the film and send the pictures back to the customer. This process became known as the Kodak system. This was the point in time when photography became accessible to the multitudes!
Today, there are machines in drugstores and film-development centers that can process a roll of film within an hour of the photograph being taken. To achieve higher quality outcomes, professional photographers often utilize the image-manipulation services of specialized photographic development centers. The emulsion process is continually being revised, and with the advent of digital photography, the two must blend together as technology evolves.
|Article By Bubba|
Bubba is the Quality Logo Products mascot. He may have started out as "just a stress ball," but he's come a long way since the company's launch in 2003. Bubba has been immortalized in numerous vector artwork designs for internal and external promotions, and you can see him change outfits on the Quality Logo Products homepage whenever a holiday rolls around. Oh, and he thinks pants are for the birds. You can connect with Bubba on Google+.
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