An oil painting on canvas of the Roman emperor Domitian, historically attributed to Titian (Tiziano Vecellio), was recently found to bear a signature reading 'L daVinci'. A 2026 Raman spectroscopy study by Thyr, Helldahl and Edvinsson analysed microscopic cut-outs from the painting and its signature area and identified thirteen pigments, all but two of which — Prussian blue and titanium white — are compatible with 16th-century practice; the study describes Prussian blue as of newer origin and titanium white as coming into common use only at a later time, and X-ray imaging indicates that at least one Prussian-blue area was probably altered after the original creation. The study leaves the painting's production history open: which regions carry post-16th-century material, whether the suspicious regions were retouched, overpainted or restored, and in how many campaigns; the original palette is mapped only at sampled points; and no attribution is claimed. The present problem asks for a reconstruction of that production history — the nature and chronology of the later interventions and the original palette wherever surviving evidence permits — together with an assessment of what the combined material, stratigraphic and documentary evidence implies for the painting's attribution (traditional Titian attribution versus the 'L daVinci' signature).

Background

In technical art history — the discipline that applies scientific instruments to questions of authorship, dating and condition of artworks — the identity and layering of pigments is a primary form of evidence, because many pigments have well-documented dates of first manufacture or common use. Raman spectroscopy identifies such compounds non-destructively at the microscopic scale: a laser is focused on the sample and the small fraction of light scattered with shifted frequencies (Raman shifts) forms a vibrational fingerprint of each molecular compound present. Its limitation for paintings is spatial: a measurement samples only the few micrometres under the laser spot, so pigment maps built from micro-samples remain pointwise unless combined with imaging techniques such as X-ray radiography, which reveals the painting's internal structure, cracks, pentimenti (artist's changes) and later alterations. Stratigraphic cross-sections — polished embedded micro-samples showing the paint build-up from ground layer to surface varnish as a sequence of layers — are the standard tool for reading the order and number of interventions on a painting. The object at issue is an old canvas depicting the Roman emperor Domitian whose creation is historically attributed to Titian (1488/90–1567). Titian's imagery of the Twelve Caesars was one of the most influential court commissions of the 16th century, and representations of the Caesars in Titian's wake circulated widely through the 17th century (documented by Vázquez-Manassero, 2015). The painting gained new attention when a signature reading 'L daVinci' was recently found on it, apparently pointing to Leonardo da Vinci (1452–1519) — a claim that material analysis can constrain but not by itself settle, since period pigments cannot distinguish a Titian from a Leonardo, a workshop collaboration, or a 16th-century copy. Thyr, Helldahl and Edvinsson (preprint posted January 2026; journal version in Materials Today Advances, August 2026) analysed microscopic cut-outs from selected areas of this painting in a Raman microscope and identified thirteen pigments: azurite (a copper carbonate blue), carbon black, chalk, cinnabar (mercury sulfide red), gypsum, lead tin yellow type 1, lead white, massicot (lead monoxide yellow), Prussian blue, red ochre, titanium white, ultramarine (lapis lazuli blue) and yellow ochre. Every listed pigment except two was in regular use in the 16th century. The exceptions are Prussian blue, an iron hexacyanoferrate pigment first synthesised in the early 18th century, which the authors describe as of newer origin, and titanium white, a titanium dioxide pigment in common industrial use only from the early 20th century, which the authors describe as present historically — 'during the Middle Ages' in the preprint abstract, 'during the Roman period' in the journal abstract — but coming into common use only at a later time (more generally, the interpretation of naturally occurring anatase, a titanium dioxide phase, is itself a classical pitfall in dating analyses; see Edwards et al., 2006). Complementary X-ray imaging showed that at least one of the areas where Prussian blue occurs has likely been altered at a later stage, offering an explanation for a modern pigment in an old painting — while the titanium-white finding's origin in the painting is not similarly explained away. What the study does not do is reconstruct the object's history. It does not establish the extent of the later interventions (which regions beyond the sampled spots carry modern materials), their chronology or staging (one intervention campaign or several; retouching, overpainting or restoration), the original palette at locations beyond the pointwise sampled spots, or any conclusion about authorship. The lead author has publicly framed the Prussian-blue areas as possible later repairs or retouching without determining which, and the authors' institution states that material analysis alone is not enough to determine who painted the artwork, art-historical investigation, provenance and other scientific analyses being needed alongside it (Uppsala University news release, 14 September 2026). The broader methodological context shows that parts of this gap are addressable in principle: for example, Hendriks et al. (2019) demonstrated that the binder of modern paint layers — the organic medium that binds pigment particles into paint — can be dated by radiocarbon methods, and large-area elemental mapping (imaging the chemical elements present across the whole surface, for instance by X-ray fluorescence) and stratigraphy are standard conservation-science practice — but none of these have been applied to this painting.

Problem Statement

For the painting of the Roman emperor Domitian historically attributed to Titian and bearing a signature reading 'L daVinci' — the object studied by Thyr, Helldahl and Edvinsson (2026) — reconstruct its production history: (i) determine which regions of the painting carry post-16th-century materials (the identified Prussian blue and possibly titanium white, and any others detectable), and the nature of those interventions (retouching, overpainting, or restoration); (ii) establish the chronology and staging of the later interventions, including whether they occurred in a single campaign or several; (iii) map the original 16th-century palette as far as the surviving evidence allows, including regions not covered by the published pointwise Raman micro-sampling; and (iv) assess, from the combined material, stratigraphic and documentary evidence, what can be concluded about the painting's attribution — the traditional Titian attribution versus the 'L daVinci' signature — including an explicit statement of what the evidence cannot decide.

References

  1. Jakob Thyr, Lars Helldahl, Tomas Edvinsson, 'Leonardo under cover', ChemRxiv preprint, posted 4 January 2026, DOI: 10.26434/chemrxiv-2026-1mp5h, https://doi.org/10.26434/chemrxiv-2026-1mp5h
  2. Jakob Thyr, Lars Helldahl, Tomas Edvinsson, 'Leonardo under cover: A Raman spectroscopy investigation of a historic painting', Materials Today Advances 31 (2026) 100871, DOI: 10.1016/j.mtadv.2026.100871, https://doi.org/10.1016/j.mtadv.2026.100871
  3. Margarita-Ana Vázquez-Manassero, 'Twelve Caesars' Representations from Titian to the End of 17th Century: Military Triumph Images of the Spanish monarchy', Actual Problems of Theory and History of Art 5 (2015) 655-663, DOI: 10.18688/aa155-7-71, https://doi.org/10.18688/aa155-7-71
  4. Laura Hendriks, Irka Hajdas, Ester S. B. Ferreira, Nadim C. Scherrer, Stefan Zumbühl, Gregory D. Smith, Caroline Welte, Lukas Wacker, Hans-Arno Synal, Detlef Günther, 'Uncovering modern paint forgeries by radiocarbon dating', Proceedings of the National Academy of Sciences 116 (2019) 13210-13214, DOI: 10.1073/pnas.1901540116, https://doi.org/10.1073/pnas.1901540116
  5. Howell G. M. Edwards, Nik F. Nik Hassan, Paul S. Middleton, 'Anatase—a pigment in ancient artwork or a modern usurper?', Analytical and Bioanalytical Chemistry 384 (2006) 1356-1365, DOI: 10.1007/s00216-005-0284-2, https://doi.org/10.1007/s00216-005-0284-2
  6. Uppsala University, 'Material analysis provides new clues about a possible da Vinci', news release, 14 September 2026, https://www.uu.se/en/news/2026/2026-09-14-material-analysis-provides-new-clues-about-a-possible-da-vinci