Colour: travels through the paintbox, by Victoria Finlay

It's pure pleasure to join this gutsy arts reporter-cum-scholar on her quest for historical pigments and dyes around the world. Victoria Finlay's exhaustive research takes her from Australia to Afghanistan, sniffing at malodorous vats of paint or scrutinising ancient statues for the glitter of ground gems.

With wry humour, Finlay maintains her sense of wonder while she pursues outlandish tales "about the people who made the things that made the art". What starts as a romantic rainbow chase spurred by a childhood memory of Gothic blue stained glass at Chartres leads her to uncover "more corruption, poisonings, wars and politics than even the Medicis could have appreciated".

The invention of secret potions for lasting colour, and the traders and users of their arcane ingredients, captivate Finlay. She doesn't hesitate to draw on lore from art history and her own conjecture about a painter's supply problems to ask all the right questions.

She seeks sacred ochre caches in the Outback, and wonders why Aboriginals used to carry lumps of the stuff thousands of miles for bodypainting rituals. She treks to subterranean veins of lapis lazuli in Taliban territory to find the source of Virgin Mary blue, and figures out why there was no need to assassinate Napoleon Bonaparte when killer green wallpaper did the trick. She buttonholes Mexican grandmothers who dye skirts purple with the tears of sea snails, and pores over forgers' prison diaries to find out why experts authenticated their mock-medieval masterpieces.

Those splodges on old palettes turn out to be anything but mundane: they contain real blood, squashed bugs, purple Phoenician seashells, even ground-up Egyptian mummies. For ultramarine, semi-precious lapis lazuli gets powdered into whipped egg yolk like some celestial mayonnaise. One hue was said to be obtained by collecting the urine from a holy cow after it gorged on mango leaves. But a wild-goose chase to Bihar in India leads Finlay to conclude that the gent from Calcutta who told her about this process was "taking the piss".

Madder is a little bush with a pink root used to produce the warm tomato red in Turkish carpets. Dutch growers refined it, and made fortunes despite calling the highest grade "krap". Intrigued by tubes of pricey rose-madder paint, still manufactured in Harrow by the firm Winsor & Newton, Finlay tours the factory but is barred from entering one top-secret room. Still, she rhapsodises about a photograph of the madder root: "It was orange and blue and red, like kingfishers' wings... a celebration of every colour imaginable."

Finlay pities the cuttlefish that had to be sufficiently scared to yield the exact tone of sepia prized by artists. Don't be put off by the twee subtitle: these travels through the paintbox are vivid indeed. Even drab (technically the tone between olive and puce) seems less so when Finlay examines it.