Though the term blackboard has a color in its name, most of them
are now not actually black. We still use the term
interchangeably with chalkboards. Now they are more often green.
A few hundred years
ago, blackboards were black. They were large boards of connected
slates that teachers could write on for the whole class to see.
The name blackboard was not used until 1815. They were usually
made with slate, but in rural areas, they were often wooden
boards painted dark with egg whites mixed with the remains of
charred potatoes. Later, they were also made of wood darkened
with a commercially made porcelain-based ink.
During the 20th
century, manufacturers began to make chalkboards using a green,
porcelain enameled paint on a steel base. By the 1960s, the
green chalkboard trend was becoming universal. Teachers had
discovered that a different colored paint was a lot more
comfortable to stare at all day, because green porcelain paint
cut down on glare.
During the 1990s,
schools began converting their classrooms to whiteboards, which
produce less dust and eliminate that telltale screeching noise.