Gelatin is vital for photography and X- Rays

Many photographers are unaware that a range of specially purified gelatins is vital to analogue and digital photography.

A roll of transparent, undeveloped photographic film consists of a two-sided strip of celluloid with chemical coatings on each side. There may be up to 20 or more individual layers, collectively less than one-thousandth of an inch thick. These imaging layers mainly contain sub-micron-sized grains of light-sensitive silver halide crystals. When exposed to light they undergo a photochemical reaction.

In the middle of the 19th century, it was discovered that gelatin was a most suitable agent for bonding these layers to the celluloid film, ensuring that the halides and other sensitizers were evenly spread, suspended and stabilised. Gelatin bonded them into a photo salt.

Silver and gelatin have since been at the heart of the fixed and moving film industry. It is why, early in the 20th century, the Hollywood movies were referred to as being shown on the ‘silver screen’.

As well as the bonding property of gelatin in making the roll of film, some of gelatin’s other versatile properties continue to be crucial to photography. After exposing the film to light and capturing the image, gelatin contributes in its development and printing.

The photographic print paper also uses gelatin-based coatings. In obtaining both the negative and then the permanent printed photograph or film, the ability of the gelatin to swell ensures the success of the photochemical reactions. In the developing and fixing baths the swollen gelatin allows chemicals access to the silver halide grains and, with fresh water, the removal of unwanted byproducts.

Present at every stage of manufacture of photographic film and printing paper—producing first the negative and then the final permanent image—is the unique and magical product of nature that is gelatin.

It is likely that few people would be aware of a connection between the photographs carried in their wallets or handbags and such things as a bowl of jelly, a marshmallow confection or a pharmaceutical capsule.

To date, no suitable substitute for gelatin has been found in the manufacture of photographic film or paper. Gelatin for photographic use is generally made from ossein derived from bone.

Gelatin and X-ray film

X-ray film is a large-format black-and-white film that is usually coated on both sides to increase its sensitivity to light. The emulsion layers contain light-sensitive silver halides embedded in gelatin. The film is protected from light irradiation in a cassette along with screens that are illuminated when exposed to X-ray radiation. What becomes visible on the film depends on how much radiation is absorbed by the body of the patient positioned between the X-ray source and the film material.

Gelatin in inkjet applications and art prints

Here, the gelatin coating is not used to protect light-sensitive substances. Instead, its swelling properties are used to enable the absorption of water-soluble printer ink by the paper. The ink is then sealed into the dried gelatin coating on the inkjet paper and thus protected from the damaging effects of sunlight and ozone. Inkjet colors would fade on papers without a gelatin coating.

In addition, several alternative photographic processes use gelatin as a carrier of the pigment or rather chemical layer. These processes are primarily used in art photography and graphic reproduction and result in prints of the highest quality.

gelatin photography
Gelatin and photography
Gelatin XRAYS