Thermofax Machines – Slightly Better Than Carbon Paper

Thermofax machines were just barely a step up from using carbon paper in the history of making copies. For drawings or graphs, Thermofax was more of a breakthrough than for text from a typewriter. Also, the copy paper was more durable and legible than carbon paper.

The Process

Minnesota Mining and Manufacturing Company (3M) introduced the Thermofax machine in 1950 . It was a form of thermographic printing and an example of a dry silver process. Thermofax provided a significant advance as the process required no chemicals, other than those present in the copy paper itself.

A thin sheet of heat sensitive copy paper lay on the original document to be copied, and exposed to infrared energy. The heat caused the silver in the copy paper to darken, creating a copy of the original document.

Thermofax machines was analogue and only made a single copy at a time. Copy paper tended to curl up and did not archive very well. Also, the user needed great skill in setting the heat level of the machine in order to get the best copies.

The Idea

Carl S. Miller, a chemist at 3M, developed the Thermofax machine. Miller was working on a way to create a simple means of reproduction to avoid having to transcribe his notes and the multiple versions of the thesis he was writing. He discovered that when he exposed heat-sensitive paper to infrared light, it would darken in the areas of higher heat. This led him to develop the Thermofax process.

Lifespan and Obsolescence

The Thermofax machine first came to market in 1950 and was a success. It was relatively inexpensive, easy to use, and produced high-quality copies. The machine found its way to businesses, schools, and government agencies. It was also popular with artists and designers, who used it to create stencils and patterns.

The Minnesota Mining and Manufacturing Company (3M) had the patent on the Thermofax machine. The patent began in 1949 and was valid for 17 years. During that time, 3M was the only company that could manufacture and sell Thermofax machines.

However, there were other companies that developed their own dry silver process copiers. These companies included Xerox, IBM, and Kodak. These companies could compete with 3M because their copiers were more affordable and easier to use. The emerging plain paper copiers eventually made digital images, thus allowing for multiple copies, enlarging, and reducing the image sizes. The Thermofax machine remained popular until the 1970s, when it gradually gave way to xerographic plain paper copiers.