An indelible pencil is one that contains a lead that cannot be erased. Indelible pencils are traditionally made with silver nitrate, but other materials may be used, and graphite is sometimes mixed into the lead for a familiar look and feel. The copying pencil, a type of indelible pencil with an aniline dye embedded in the lead, is a close relative.
In the early 1800s, indestructible pencils were introduced as an alternative to the cumbersome and sometimes expensive pens of the time. Documents with any sense of permanence had to be written with fountain or quill pens prior to the introduction of the indelible pencil. Indelible pencils provided the desired long-lasting print without the associated difficulties; indelible pencil markings stayed put even if the document was tried to be erased or if it was dropped into water or a solvent.
Pencil companies expanded on the concept of the indelible pencil to create the copying pencil in the mid-1800s. When the aniline dye in copying pencils is exposed to water, the aniline dye dissolves, resulting in a purple ink. Someone who wanted to make a mirror-image copy of a document could write it out with a copying pencil and then blot it with a moist piece of paper. The writing was usually written on thin paper or tissue so that it could be read through the paper.
Indelible pencils are not as common as they once were, thanks to the rise of the ballpoint pen and other low-cost permanent marking alternatives, but they are still available. Some artists prefer to use them because they don’t smudge and can be used to mark items that would otherwise be damaged or compromised by ink pens. Indelible pencils can be found in art supply stores and occasionally in hardware stores.
To avoid confusion, indestructible pencils are usually clearly marked. The lack of an eraser on the end of an indelible pencil can also be used to identify it, as the marks left by these pencils cannot be erased. It’s a good idea to keep indelible and regular pencils separate, though, to avoid making costly mistakes.