What You Actually Smell in Ink — The Glue Called Nikawa

It Isn't the Soot You Smell

Grind an inkstick and a smell fills the room — sweet, faintly medicinal, close to dry earth. For a long time I assumed that smell came from the soot. The stick is black, so the smell must come from the black side of it.

It doesn't. An inkstick is made of only three things: soot, glue, and fragrance. And the smell at the heart of it comes not from the soot that makes the black, but from the glue that binds that soot into a solid stick. Soot on its own is nearly odorless. The scent rises from the part that works behind the black.

Nikawa Comes from an Animal

Nikawa is animal glue, drawn by simmering the hide and bone of cattle or deer for a long time. It is almost entirely collagen — the same material used in Japanese-painting pigments and in woodwork. Soot alone will not fix to paper or stone, so the glue coats each grain of soot, holds it to the sheet, and gives the dried line its sheen. Making ink is, at bottom, the work of binding soot with glue and pressing it into a stick.

That is why ink smells a little like old leather or aspic. A freshly cut stick smells sweet and heavy because its glue is still young and fully alive. For ink to age is for that glue to settle and dry. As I wrote in the piece on blue and brown ink, an aged stick drifts toward an earthy color and smell precisely because, over the years, the glue calms and its sweetness recedes.

The Cool, Medicinal Note Is Added Last

So where does ink's cool, clean, almost medicinal note come from — the one that passes through the back of your nose? Not the glue, not the soot, but a fragrance added at the very end of making. Most often it is ryūnō, borneol: a cool, penetrating crystal much like camphor, which tempers the raw sweetness of the glue and lifts the whole smell into something refined. Finer sticks may carry musk or sandalwood as well.

The fragrance isn't only decoration. Because the glue is an animal product, it can spoil with damp and time, and the coolness of borneol both masks and guards against that turn. When I test an expensive stick, the first thing I check is this note — where the glue's sweetness and the borneol's coolness balance, grinding it makes my breathing go deep. Ink that carries its own scent lives, for me, on the same ground as burning incense before I write.

The Day Weak Glue Ruined a Sheet

The glue that is the source of ink's smell is also the source of its difficulty.

In the rainy season I once ground an old stick whose smell was stronger than usual and dissolved oddly fast — the glue had loosened in the damp. I drew a thick line across a hansetsu sheet (35 × 136 cm) anyway, and once it dried the ink had thinned, lost its sheen, and lifted as powder when rubbed. Ink with failing glue still makes black, but it has lost the power to hold to paper. The whole batch went to waste.

Since then I read ink by its smell. When the sweetness clouds toward something sour, the glue has spoiled; when only the coolness stands and the sweetness is thin, the stick is too dry to grind well. Keep ink somewhere cool and dry, away from sun and humidity — like caring for an inkstone, if you use the material without knowing its side of the story, it will trip you somewhere.

Ink's smell is not ornament. It is a direct report, straight to the nose, of what state the binding glue is in today. To grind while smelling is to check whether you and that one stick are still speaking.