A chemometric study of ageing in lead-based paints

Question

1. What are the contributions in "A chemometric study of ageing in lead-based paints" ?

2. What are the future works in "A chemometric study of ageing in lead-based paints" ?

3. What is the effect of UV-accelerated ageing on the top layer of paint?

4. How can the spectroscopic analysis of paints be improved?

Accepted Answer

In this work, the authors employ FT-Raman spectroscopy, together with a simple spectral-deconvolution algorithm, to study in detail the spectral changes accompanying the natural and UV-accelerated ageing of simulated medieval paint films.. Finally, the authors investigate the possibility of using their chemometric deconvolution technique, in conjunction with multivariate analysis, for the semi-automated characterisation of the degree or extent of ageing in unknown samples.. The authors find that the two processes differ significantly, and that spectroscopic signatures, principally in the fluorescence background, can thus be used to differentiate the two modes of ageing and hence possibly to identify attempted forgeries.. Their studies also suggest that paints based on proteinaceous binders are more stable to ageing than lipid-bound ones.

Accepted Answer

Overall, this work highlights the utility of spectroscopy in conservation science, and illustrates how combining data from complementary techniques with suitable analysis tools might in the future be used for the automated characterisation of e. g. works of art against a database of references.

Accepted Answer

On UV-accelerated ageing, it is probable that the top layer of paint undergoes oxidative degradation, resulting in the formation of species containing double and triple C-C bonds.

Accepted Answer

The chemometric-decomposition algorithm, used to pre-process the FT-Raman data (e.g. by removing the fluorescence background), can also in some cases be used to improve the discrimination between sets of samples in these analyses.

Accepted Answer

In many cases, the authors found that ageing led to a reduction in band intensity, often accompanied by the broadening of weaker spectral features which, in some cases, led to their being barely visible above the background noise.

Accepted Answer

FT-Raman spectra within the spectral range of 20-3600 cm-1 were collected using a Bruker Ram IIinstrument (1064 nm excitation wavelength, ~1 mm spot size, KBr beam splitter and Ge detector, 2.37 mm penetration depth) at a resolution of 4 cm-1.

Accepted Answer

Understanding and identifying the colour palettes and painting techniques used in a piece of artwork canbe key to identifying the artist or studio responsible for its creation.

Accepted Answer

In the analyses of the naturally-aged samples, the authors found that the different binders/concentrations formed fairly-well separated bands when background-corrected Raman spectra were used, whereas using the chemometric spectra led to tighter and often overlapping clusters.

Accepted Answer

Accelerated ageing appears to lead to a general increase in the height of the fluorescence background, particularly noticeable for the EW and WO spectra, and in some cases also causes a shift to higher wavenumbers.

Accepted Answer

Ageing of paints can, in general, be affected by humidity, temperature and light conditions, and moststudies have been carried out on binders that are oils and other fatty acids, where the yellowing and cracking of paints is apparent[23].

Accepted Answer

while proteinaceous binding media are observed to be relatively stable, not much work has been done to understand their ageing.

Accepted Answer

The loading plots for the analyses performed with the chemometric spectra, on the other hand, do not appear to display any prominent features in the C-C multiple-bond region, which suggests that therelatively poorer grouping of samples in the PCA plots may be due to the chemometric decomposition failing to identify subtle peaks close to the background noise for samples where ageing leads to such poor-quality spectra.

Accepted Answer

the amide The authorand III bands between ~1280 and 1650 cm-1 were absent in the aged samples, possibly due to broadening, and were observed only in one or two spectra of EW- and EY-based paints.

Accepted Answer

This is consistent with reports of differential changes in the compositions of the top and bulk layers of paint on accelerated ageing, with the absence of short-chain acids on the top layer identified using secondary ion mass spectrometry (SIMS)[37].

A chemometric study of ageing in lead-based paints

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Most frequently asked questions

1. What are the contributions in "A chemometric study of ageing in lead-based paints" ?

2. What are the future works in "A chemometric study of ageing in lead-based paints" ?

3. What is the effect of UV-accelerated ageing on the top layer of paint?

4. How can the spectroscopic analysis of paints be improved?

5. What was the effect of ageing on the spectral quality of the PCA?

6. How many spectra were collected using a Bruker Ram II instrument?

7. What can be done to identify the artist responsible for the creation of a piece of artwork?

8. What did the authors find in the analyses of the naturally-aged samples?

9. What is the effect of accelerated ageing on the fluorescence background?

10. What is the common reason for the ageing of paints?

11. What is the way to study the ageing of proteinaceous binders?

12. What is the effect of the loading plots on the spectra of the UV-aged?

13. What is the reason for the absence of amide The authorand III bands in the aged paints?

14. What is the effect of UV on the composition of the top and bulk layers of paint?

Citations

Automated characterization of varnishes photo-degradation using portable T-controlled Raman spectroscopy.

Estimation of semiconductor-like pigment concentrations in paint mixtures and their differentiation from paint layers using first-derivative reflectance spectra

Consistent Characterization of Color Degradation Due to Artificial Aging Procedures at Popular Pigments of Byzantine Iconography

Desarrollo de metodologías analíticas basadas en espectrometría de masa y espectroscopía infrarroja para la identificación de aglutinantes orgánicos y sus productos de degradación en arte colonial

The conservation of polymeric materials in museum collections using advanced surface science and surface analysis techniques

References

Raman spectroscopy as a means for the identification of plattnerite (PbO2), of lead pigments and of their degradation products.

FTIR studies of the effects of pigments on the aging of oil

Quantitative analysis of oils and fats by Fourier transform Raman spectroscopy

Applications of synchrotron-based micro-imaging techniques to the chemical analysis of ancient paintings

The characterisation of lead fatty acid soaps in ‘protrusions’ in aged traditional oil paint

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