Hidden in plain sight: Revisiting the synthesis, characterisation, degradation and the intricate relationship between Scheele’s green and Emerald green

Hidden in plain sight: Revisiting the synthesis, characterisation, degradation and the intricate relationship between Scheele’s green and Emerald green | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Hidden in plain sight: Revisiting the synthesis, characterisation, degradation and the intricate relationship between Scheele’s green and Emerald green Leonardo Pantoja Munoz This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3755191/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Carl Wilhelm Scheele's legacy is primarily associated with the creation of a notorious toxic pigment, commonly referred to as "Scheele's green." The identification of Scheele's green in comparison to Emerald green poses theoretical complexities. Common assumptions about the degradation of Emerald green suggest dissociation in acidic pH conditions, generating mobile arsenic trioxide and copper ions, followed by oxidation to As(V), which can co-precipitate with Fe, Al, and Ca ions. In this study, the fabrication of Scheele’ green was reproduced using historical recipes, with a specific focus on maintaining the pH of the arsenite solution at 9.3. The study explores its relationship with Emerald green and the challenges associated with identification, aiming to inform heritage object preservation and enhance health and safety guidelines for pigment handling. Maintaining the pH at 9.3 proved influential in obtaining a crystalline product with an intense Raman signal, aligning with the widely accepted spectra of Scheele’s green. However, Raman spectra from amorphous copper-arsenite samples consistently exhibit broad bands at 288 and 845 cm -1 , prompting a proposed modification for a dual representation of the pigment: the “common” form with broad bands and the “uncommon” or crystalline form reported in the literature. Demonstrating that the crystalline form shares nearly identical Raman and FTIR spectra implies an identical chemical composition to Trippkeite. Evidence presented highlights that copper-arsenic-based pigments contain adsorbed free copper, arsenite, and arsenate ions prone to migration, challenging commonly described degradation pathways. The hypothesis presented here, that Emerald green synthesis may inadvertently yield small amounts of Scheele’s green urges caution in pigment identification using Raman spectroscopy. Additionally, the study reveals, for the first time, the occurrence of Scheele’s green in a book, with particles exhibiting a spherulite form, challenging identification of Emerald green solely based on morphology. Arsenic Emerald green Scheele’s green speciation degradation Full Text Supplementary Files SupplementmaterialforHiddinginplainsight.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 18 Dec, 2023 Reviewers invited by journal 18 Dec, 2023 Submission checks completed at journal 18 Dec, 2023 First submitted to journal 17 Dec, 2023 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3755191","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":265485062,"identity":"38181051-9c52-428f-a1fd-e29360ca26b3","order_by":0,"name":"Leonardo Pantoja Munoz","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA90lEQVRIiWNgGAWjYBACPijNDKVtGBgOQFgGuLSwgckEuJY04rXAwGFitPAe/Fz4w4adf9oZswcf/pyP5ruRwPjhB8NhY9xa+JKlZySkMUvczjE3nMFzO3fmmQPMkj0Mh81wa+ExkOZJOMzMcDvHTJpH4nbuhuMNDNJAF9rg0WL8G6RFHqzF4FzuhsMMzL8JaDED22IA1pJwAGQLG8gW3A5j5kuz5klLYza8nVYmOeNAMtAvB9ssewzScXqfn7338G0eG5tkudvJ2yQ+/LHL7buRfPjGjwprwwZceph5wFQykhBjA55YAQGIFjt8SkbBKBgFo2CEAwDLjU1/F3NBLgAAAABJRU5ErkJggg==","orcid":"","institution":"Department of Natural Sciences, Faculty of Science and Technology, Middlesex University","correspondingAuthor":true,"prefix":"","firstName":"Leonardo","middleName":"Pantoja","lastName":"Munoz","suffix":""}],"badges":[],"createdAt":"2023-12-14 19:44:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3755191/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3755191/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":49303602,"identity":"40812dbd-4042-4b2e-af2d-28fa2a1365c2","added_by":"auto","created_at":"2024-01-08 10:39:22","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1475338,"visible":true,"origin":"","legend":"","description":"","filename":"HiddeninplainsightV3.0.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3755191/v1_covered_bc2303fc-dbf7-4682-b897-fbc93fd5b45a.pdf"},{"id":49303231,"identity":"eca15155-8f6e-4780-af7f-51f379d9fc43","added_by":"auto","created_at":"2024-01-08 10:31:17","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":18140885,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementmaterialforHiddinginplainsight.docx","url":"https://assets-eu.researchsquare.com/files/rs-3755191/v1/68b9ea98297bed5bd393446e.docx"}],"financialInterests":"","formattedTitle":"Hidden in plain sight: Revisiting the synthesis, characterisation, degradation and the intricate relationship between Scheele’s green and Emerald green","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"npj-heritage-science","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"hsci","sideBox":"Learn more about [Heritage Science](http://heritagesciencejournal.springeropen.com)","snPcode":"40494","submissionUrl":"https://submission.nature.com/new-submission/40494/3","title":"npj Heritage Science","twitterHandle":"@SpringerOpen","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Arsenic, Emerald green, Scheele’s green, speciation, degradation","lastPublishedDoi":"10.21203/rs.3.rs-3755191/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3755191/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCarl Wilhelm Scheele's legacy is primarily associated with the creation of a notorious toxic pigment, commonly referred to as \"Scheele's green.\" The identification of Scheele's green in comparison to Emerald green poses theoretical complexities. 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