Salvator Mundi: an investigation of the painting’s materials and techniques
Bibliographic record
Abstract
Abstract Before the start of its restoration in 2007, the Salvator Mundi was thought to be one of a number of copies of a long-lost Leonardo da Vinci painting, depicting Christ giving a blessing with his right hand while holding a crystal orb in his left. During the restoration treatment, a scientific examination of the painting was carried out to elucidate the painting’s materials and techniques. Microscopic sampling of the painting was necessarily limited, and nine out of ten samples were prepared and analyzed as cross-sections. A number of analytical methods were employed selectively, including stereomicroscopy, visible and fluorescent light microscopy, scanning electron microscopy with energy dispersive spectroscopy, Raman microspectroscopy, Fourier transform infrared microspectroscopy in transmission mode and with attenuated total reflection. The pigments characterized were lead white, vermilion, red iron oxide earth, red lake, natural ultramarine, lead–tin yellow, umber, and charcoal, carbon and bone blacks. Manganese-containing soda-lime glass was detected in the ground, imprimitura and paint layers, and a walnut oil medium was identified by pyrolysis gas chromatography-mass spectrometry. Cross-section studies revealed aspects of the painting’s stratigraphy: a size layer, white ground and off-white imprimitura, followed by a complex sequence of paint layers applied by the artist to achieve sophisticated visual effects.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".