What is Emulsion and Why Does Water Damage It?

Films—such as x-rays and negatives—are sensitive to temperatures, relative humidity levels and water. X-rays have a base, or plastic backing, and emulsion. The emulsion toughens under light and makes the image more durable. Unlike true emulsions, those used for films are a suspension of solid particles in a gelatin solution. When a medical facility suffers water damage that affects films, x-ray restoration is critical to preserving valuable patient information.

The Science of Photographic Emulsions

Photographic emulsions are light-sensitive coatings on film made up of grains of micron-sized silver halide or bromide crystals suspended in a gelatin. When you expose the photosensitive crystals to light, they undergo a chemical change that allows images to appear on bases.

The atoms in the silver crystal contain a positive ion with a missing electron. Each bromine or halide particle has a negative ion and an extra electron. Upon exposure to light, the photons remove the extra electron from the bromide or halide ions, allowing it to wander in the crystal. The electron then gets trapped in a crystal’s lattice flaw. The same also happens to some of the silver ions. The trapped electron creates a negative electric field that attracts a positive silver ion to it. When the electron and ion meet, they form a neutral silver atom, forming the beginning of a latent image. This process occurs several times until there is a group of four to six neutral silver atoms, a cluster that’s big enough to become a fully formed latent image.

When you expose the silver atoms to developing chemicals, the crystals form grains of metallic silver, and the original cluster of atoms increases in size. The more light exposure to the silver atoms, the darker the image.

How Water Damages X-Rays

When water comes in contact with an x-ray, bacteria begin to grow, creating an environment that’s conducive to mold growth. At first, the film changes to color, acquiring a bluish or purplish hue. As the gelatin in the emulsifier dissolves, the film feels slippery. As water damage progresses, an x-ray emulsion separates from the base, eventually becoming a gray, soupy substance.

• Contact a document restoration specialist as soon as you notice water or moisture damage on x-rays.
• Turn down the temperatures in the room to the lowest setting possible to slow deterioration.
• Place the x-rays in containers filled with cold clean tap water. Use a separate container for each affected film. If you find some x-rays stuck together, do not try to separate them because this may cause irreparable damage. Instead, place them both in the same water-filled container. You may find that they separate on their own.
• While the x-ray is in the container, allow running water to flow into it so you can rinse off debris.
• Keep the x-rays wet until the x-ray restoration specialists arrive. Refresh the water in the containers every 24 hours.
• Place a dehumidifier in the affected room or where you placed the x-rays that did not get wet to eliminate excess moisture.

When Polygon arrives on the scene, specialists will carefully pack the x-rays and transport them in a climate-controlled vehicle to a secure drying facility. Technicians then use a special solution to hand-clean the films gently before rinsing them. The x-rays then hang in a climate-controlled environment to air dry. To learn more about x-ray restoration or to receive assistance with creating a preparedness and restoration plan for your medical charts, contact Polygon today.

[Photo from Michael Dorausch via CC License 2.0]