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dc.contributor.authorKeiller, Lauren
dc.contributor.authorPatterson, Iain L. J.
dc.contributor.authorStewart, Dominic
dc.contributor.authorSmellie, Iain
dc.identifier.citationKeiller , L , Patterson , I L J , Stewart , D & Smellie , I 2023 , ' A simple and inexpensive invisible ink system based on red cabbage extracts ' , Journal of Chemical Education , vol. Articles ASAP .
dc.identifier.otherPURE: 283441989
dc.identifier.otherPURE UUID: bed143d5-6bf8-48ed-a461-81265c19bbdb
dc.identifier.otherORCID: /0000-0002-5829-6487/work/130204500
dc.identifier.otherScopus: 85149140212
dc.description.abstractThe use of red cabbage (Brassica oleracea var. capitata F. rubra) extract as a pH indicator is a versatile and popular demonstration that is employed by educators in many schools and universities. Previous variations of this demonstration have used red cabbage extracts to prepare paper that changes color when solutions of acid or base are applied as “inks”. In this report, we highlight the ability of red cabbage extracts to function as invisible inks. Colorless solutions are prepared by bleaching anthocyanin extracts with aqueous sodium metabisulfite, and the resulting mixture can then be used to write hidden messages on paper. The invisible messages can be revealed by the addition of citric acid solution, or by using potassium aluminum sulfate (alum) as developers. The demonstration does not require specialist equipment or chemicals, and options to use additional plant sources to prepare the ink are described.
dc.relation.ispartofJournal of Chemical Educationen
dc.rightsCopyright © 2023 The Authors. Published by American Chemical Society and Division of Chemical Education, Inc. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.en
dc.subjectHigh school/introductory chemistryen
dc.subjectFirst-year undergraduate/generalen
dc.subjectAqueous solution chemistryen
dc.subjectQD Chemistryen
dc.titleA simple and inexpensive invisible ink system based on red cabbage extractsen
dc.typeJournal articleen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews. Centre for Higher Education Researchen
dc.contributor.institutionUniversity of St Andrews. EaSTCHEMen
dc.contributor.institutionUniversity of St Andrews. School of Chemistryen
dc.description.statusPeer revieweden

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