Monitoring the photographic process, degradation and restoration of 21st century Daguerreotypes by wavelength-dispersive X-ray fluorescence spectrometry
Bibliographic record
Abstract
This study applied wavelength-dispersive X-ray fluorescence spectrometry (WDXRF), with its high spectral resolution, to monitor the photographic process, tarnishing and restoration of pristine Daguerreotypes made in the traditional 19th century fashion. The elemental changes upon restoration via thiourea treatment, were evaluated and compared to a method based on bulk electrolysis. The WDXRF system was found to successfully resolve all lines of interest including in the mercury-bromine-gold region. Sulfur, one of the main components of tarnish, was removed efficiently from the surface of the Daguerreotype when restored by electro-cleaning. Restoration by thiourea immersion removed sulfur from the surface of the Daguerreotype to a point at which the residual sulfur was equivalent in content to the residue left after gilding (i.e. from thiosulfate). Thiourea treatment was found to remove a significant amount of gold from the surface of the Daguerreotype, which may explain the sometimes observed dullness imparted to the Daguerreotype after restoration with thiourea. Also, Daguerrian measles were found to accumulate on thiourea treated plates versus those cleaned by electro-cleaning which ultimately negatively imparts further artefacts to the image after restoration.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".