Marty Writing Letter To Doc

Marty writing his letter to Doc, using a fountain pen filled from an ink bottle (on the table in front).

The fountain pen was the preferred formal writing instrument for personal use in 1955. It dominated until the 1960s, when the ballpoint became reliable enough for common use. Other writing instruments in 1955 were the pencil — which George McFly is seen using to write his science-fiction stories — and the dip pen, which was a steel nib without a built-in ink reservoir.

Marty McFly used a fountain pen to write his warning letter to Emmett Brown in Lou's Cafe.

In 1955, the usual way of filling a fountain pen was from an ink bottle (as Marty did), using a piston or some other sucking mechanism on the pen.