How highlighters are made
Most yellow highlighters glow because of a single dye called pyranine.
- stations
- 6
- things upstream
- 45
- raw sources
- 16
- steps from the ground
- 8
The short version
A highlighter is a felt-tip marker filled with transparent fluorescent ink instead of opaque ink. The barrel and cap are molded plastic, the nib is porous fiber or sintered plastic, and a fiber reservoir inside soaks up a measured dose of ink. Ink then wicks from reservoir to nib.
-
Dissolve the fluorescent dye
A fluorescent dye is dissolved in a liquid so the ink is see-through instead of opaque. Pyranine gives the common yellow, and rhodamines make other colors.
Goes in -
Mold the body
Barrel, cap and plugs are molded from plastic resin in the same way as for other markers.
Goes in -
Form the chisel nib
Nibs are either polyester fiber held by a bonding resin, or polyethylene powder sintered into a porous shape. The chisel shape lets one stroke cover the full line of text.
Goes in -
Slide in the reservoir
A cylinder of packed fibers in a thin seal slides into the barrel. Crushing it or setting it off-center hurts how it holds and releases ink.
Goes in -
Dose the ink
An automated head dispenses a measured amount of ink into the reservoir, which soaks it up like a sponge.
-
Press nib, cap and test
Operators press the nib in until it touches the saturated reservoir, and the cap and end plug are seated. A bad cap seal dries a pen out in weeks, so pens are checked for flow and leaks.
Worth repeating
- Dr. Frank Honn invented the first highlighter in 1963, and Carter's Ink Company produced it under the name Hi-Liter.
- Yellow is the preferred highlighter color for marking pages you will photocopy, because it does not cast a shadow on the copy.
Back to the ground
Follow every input upstream and highlighter starts as these 16 raw sources.
Everything it is made of See it on the map
Open the whole family tree
Keep walking
Sources
- Highlighter
- Marker Pen Machine: The Complete Manufacturing Guide
- Highlighter Nibs and Reservoirs
- Marker
Cite this page: "How highlighters are made." Assembly Line, 2026-11-03. https://assemblyline.org/make/highlighter