Ground Truth · a lie about a painting, broken by a fact about matter
The Pigment That Hadn't Been Born Yet
People imagine forgery is caught by a connoisseur spotting a wrong brushstroke. The durable catch is colder than that. Every pigment has a documented birthdate — the year it was first made — and a "Vermeer" containing a colour invented after Vermeer died in 1675 is not a bad painting. It is a chemical impossibility.
A forger can copy a style perfectly and still be undone by one molecule with a paper trail. That is exactly what happened to Han van Meegeren, whose fake Vermeers fooled the experts of the 1930s and 40s — until chemistry found, in the blue of his wartime forgeries, traces of cobalt blue (first synthesised 1802), and, throughout, the phenol-formaldehyde resin (the Bakelite family, 1907) he baked into the paint to fake aged cracks. Below is the instrument that does the convicting. Slide a painting's claimed creation year along the pigment timeline. For each pigment present, a bar runs from the year it was born to today; any bar that starts after the claimed year flares red. The verdict is not an opinion — it is two numbers compared.
Pick a case, then drag the claimed date below.
Drag left, before 1675, to claim a real Vermeer. Drag right and the modern pigments stop being impossible — because by then they had been invented.
That is the whole logic of material anachronism. It does not need a trained eye, and it does not argue about quality. It asks one question of every speck of colour — could you have existed yet? — and a single "no" is fatal. The connoisseur's verdict is a judgement; this one is a date.
The check — the verdict recomputed in front of you
For the loaded case at claimed year 1665, each pigment's documented earliest-availability year is compared to the claim. The rule is one line, and it runs live:
| pigment | born | claimed | verdict | source |
|---|
—
Run it yourself: node research/pigment-that-wasnt-born/verify-pigment-that-wasnt-born.mjs. It recomputes every verdict on this page from the same birthdates and the same one-line rule.
The dates — with their real ranges, and what they do not claim
Why ranges, not single years. A pigment's "birthdate" is genuinely fuzzy: there is the date of first laboratory synthesis, of a published recipe, of the prize that announced it, and of the first commercial paint a working artist could buy — and these can be decades apart. The instrument uses the earliest defensible availability year for the conviction (the kindest-to-the-forger reading: if even the earliest date is after the claim, the anachronism is certain). The honest range for each is below.
The timeline shows the logic, not the lab. You cannot date a pigment by eye. Detecting cobalt in an ultramarine, or Bakelite in a crack, takes real instruments — X-ray fluorescence (XRF), Raman spectroscopy, paint cross-sections under the microscope, and gas chromatography for the resin. What is computed here is the consequence once the analysis is done: a pigment older than its invention is impossible, full stop. The instrument is the verdict, not the assay.
What van Meegeren's works actually contained, attributed. Different forgeries and different modern re-examinations found different markers, so they should not be blurred together. His earliest masterpiece, The Supper at Emmaus (1936–37), in fact used period-correct natural ultramarine for the blue — so the cobalt anachronism is not that painting's. The modern cobalt blue (an 1802 synthetic) turns up in his wartime forgeries: by then natural ultramarine was unavailable in the occupied Netherlands, so for Christ with the Adulteress (sold to Göring, 1942) he reached for cobalt — and traces of cobalt blue were found in two of the forgeries (Coremans's 1949 examination; The Art Newspaper; Chemistry World). That is the case loaded here, which is why it flags cobalt. Separately, the Courtauld's version of The Procuress, tested in 2011 by the Courtauld and the Rijksmuseum for the BBC's Fake or Fortune?, contained the phenol-formaldehyde resins Bakelite and Albertol used as paint hardeners — a 20th-century material in a purported 17th-century work. Van Meegeren's technique across the forgeries was to grind pigment into a phenol-formaldehyde resin medium and bake it to harden, which is the marker the Adulteress case carries alongside the cobalt.
The free choices. "Present in the work" is a modelling switch you control by loading a case — the chemistry of detection is upstream and assumed done. "Today" is fixed at 2026 so every pigment's bar has a right edge. Antiquity pigments are drawn from a left edge of 1600 (the start of the visible scale), not their true age; their birthdates are all far earlier than any date you can drag to, so they never flag — which is correct.