Chromatography in Inks

Footage captured by Tadaima Pen

Some fountain pen inks hide more than one colour in the bottle. Add a drop of water to a dry swatch, or let a wet stroke spread across absorbent paper, and a single colour can split into bands of blue, pink, yellow or green. This is ink chromatography, and it is one of the most surprising things a fountain pen ink can do.

In the clip, you'll see swatches of multi-dye inks parting into two or more tones as they spread and dry.

What is Chromatography, Exactly?

Chromatography is a way of separating a mixture into its parts. Many fountain pen inks are blended from several dyes to make one colour. When water travels through paper, it carries those dyes along with it, but not all at the same speed. Dyes that dissolve easily and cling less to the paper fibres travel further, while others stay close to where they started. The result is a set of coloured rings or bands, a little like a fingerprint of the ink's recipe.

What Affects Chromatography?

A few things decide how dramatic the chromatography will be:

• Dye Blend: Inks mixed from several dyes separate the most. Inks made from a single dye, or from pigments, barely separate at all.

• Paper Absorption: Absorbent paper, like coffee filters or chromatography paper, lets water wick through quickly and spreads the colours wide. Smooth, coated papers keep the ink where you put it.

• Water: The dyes need something to carry them. A drop of water on dried ink, a wet brush, or a strip of paper standing in water all work.

• Time: The longer water keeps moving through the paper, the further apart the colours travel. Let it dry completely to see the final bands.

Try It at Home

Draw a thick line of ink about 2 cm from the bottom of a strip of coffee filter paper and let it dry. Stand the strip in a glass with a little water, keeping the ink line above the water. Watch the water climb and carry the colours with it, then lay the strip flat to dry. It's a lovely way to discover the colours hiding in your favourite inks.

Why Do Artists Love It?

Chromatography turns a single ink into a small palette. One wash can bloom into a sky, a sunset or a leaf with gradients of its own, without mixing a second colour. A drop of water on a finished piece can also open soft halos of colour where you want them.

Have you tried chromatography with your inks? Which ink surprised you the most? Let us know in the comments below!