IBM Selectric Typewriter - Ribbons

Ribbons

In addition to the "typeball" technology, Selectrics were associated with several innovations in ink ribbon design.

The original Selectric had to be ordered to use either cloth reusable ribbon or one-time carbon film ribbon; the same machine could not use both. This was also true of the original, non-correcting Selectric II. IBM had used a similar carbon film ribbon on their earlier "Executive" series of typewriters. As with these older machines, the carbon film ribbon presented a security issue in some environments: It was possible to read the text that had been typed from the ribbon, seen as light characters against the darker ribbon background.

The Correcting Selectric II used a new ribbon cartridge mechanism. The cartridge contained both supply and take-up spools, permitting both easy ribbon changes and the use of several types of ribbon on one machine. The ribbons were wider than had been used previously, giving more typed characters per inch of ribbon. Successive characters were staggered vertically on the ribbon, which incremented less than a full character position each time. Different types of ribbons had different-depth holes in the bottom of the cartridge, which set the mechanism to advance the ribbon by the amount appropriate for the type of ribbon.

Three types of ribbons were initially available for the Correcting Selectric II: Reusable cloth ribbon (essentially the same has had been used on typewriters for decades); carbon film ribbon, like that used on earlier Selectrics; and the new Correctable (carbon) Film ribbon. The latter used a carbon pigment similar to that on the regular carbon film ribbon, but its binder did not permanently adhere to the paper. This permitted the use of the adhesive Lift-Off correction tape in the new machine, producing a very "clean" correction. The other types of ribbons required Cover-Up tape, which deposited a white ink on top of the characters being corrected. This complicated corrections on paper colors other than white.

Shortly after the machine was introduced, a "Tech-3" ribbon appeared. It essentially replaced the cloth ribbon, as it offered typing quality close to the film ribbon but at a use cost comparable to the reusable cloth. Like the cloth ribbon, Tech-3 ribbons incremented only a fraction of the character width after being struck. Unlike the cloth ribbon, the Tech-3 ribbon provided high quality impressions for several characters from each spot on the one-time-use ribbon. Because characters overstrike each other on a Tech-3 ribbon several times it could not be easily read to discover what had been typed. The Tech-3 ribbon offered equivalent security to the carbon film ribbon, as its impressions were permanent as soon as they were struck. The Tech-3 ribbon was used with the same cover-up tape that worked with the other non-correctable ribbons.

The thumb wheel on the ribbon cartridge and the correction tape spools were color coded so they could be easily identified and matched with the appropriate correction tapes: Yellow for the correctable film ribbon and Lift-Off tape; gray, pink, and blue for cloth, carbon film, and Tech-3, respectively. Later another type of correctable film ribbon and lift-off tape appeared, both color coded orange. The yellow meant the ribbon was a higher quality and would produce a better quality type image. Orange was a lower cost ribbon for everyday typing. The yellow and orange coded lift-off tapes would work with either ribbon type.

The slightly adhesive Lift-Off tape would sometimes damage more delicate paper surfaces. A less "sticky" version of these tapes was eventually offered, but some people believed it didn't remove the ink as well. Some typists found that a piece of adhesive tape such as "Scotch" tape could be used in place of lift-off tape.

Some colored ribbons (such as brown) were also available. The ribbon cartridge mechanism did not allow the use of two-color ribbons, such as black and red, that had been common on earlier typewriters.