Fountain pen ink
Fountain pens, first sold in late 19th century, contain a reservoir of writing ink that is wicked out by paper fibers. Typically fountain pen ink is very water soluble and may contain tannic, gallic and hydrochloric acid. Some black ink colors may partially separate on paper producing a blue halo around a black center. Many blue and black fountain pen inks fade in sunlight.
Resources and Citations
- Book and Paper Catalog; AIC Wiki