{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,25]],"date-time":"2026-09-25T01:27:18Z","timestamp":1790299638662,"version":"4.1.0"},"reference-count":20,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2022,9,24]],"date-time":"2022-09-24T00:00:00Z","timestamp":1663977600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Heritage Board"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>ATR\u2013FTIR (attenuated total reflection\u2013Fourier-transform infrared) microscopy with imaging is widely used in the heritage field to characterise complex compositions of paint cross-sections. However, some limitations include the need for ATR crystal contact with the sample and the inability to resolve particle size below the IR diffraction limit. Recently, a novel O-PTIR (optical-photothermal infrared) spectroscopy technique claimed to open a new avenue for non-invasive, efficient, and reliable analysis at sub-micron resolution. O-PTIR produces transmission-like FTIR spectra for interpretation, without the need to touch the sample, which are highly favourable attributes for analysing heritage samples. This paper reports the comparison of O-PTIR and ATR\u2013FTIR techniques applied to a cross-section embedding a thin paint fragment that delaminated from a late 19th to early 20th-century oil portrait. The hazy paint fragment consisted of zinc soaps (both crystalline and amorphous), gordaite (NaZn4Cl(OH)6SO4\u00b76H2O), and zinc lactate, that could not all be well-resolved with ATR\u2013FTIR imaging. With O-PTIR analysis, the degradation compounds could be resolved at sub-micron resolution with an equivalent or better signal-to-noise ratio. This case study shows how the two techniques can be used to obtain comprehensive information at a broad level with ATR\u2013FTIR and a detailed level with O-PTIR.<\/jats:p>","DOI":"10.3390\/molecules27196301","type":"journal-article","created":{"date-parts":[[2022,9,26]],"date-time":"2022-09-26T01:41:58Z","timestamp":1664156518000},"page":"6301","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Comparison of ATR\u2013FTIR and O-PTIR Imaging Techniques for the Characterisation of Zinc-Type Degradation Products in a Paint Cross-Section"],"prefix":"10.3390","volume":"27","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1061-8210","authenticated-orcid":false,"given":"Lynn","family":"Chua","sequence":"first","affiliation":[{"name":"Heritage Conservation Centre, National Heritage Board, Singapore 619104, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6268-1081","authenticated-orcid":false,"given":"Agnieszka","family":"Banas","sequence":"additional","affiliation":[{"name":"Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0509-044X","authenticated-orcid":false,"given":"Krzysztof","family":"Banas","sequence":"additional","affiliation":[{"name":"Singapore Synchrotron Light Source, National University of Singapore, Singapore 117603, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,9,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"274","DOI":"10.1016\/j.vibspec.2010.04.006","article-title":"Macro-ATR-FT-IR spectroscopic imaging analysis of paint cross-sections","volume":"53","author":"Joseph","year":"2010","journal-title":"Vibrat. 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