ISO INTERNATIONAL STANDARD 10309 First edition 1994-12-01 Metallic coatings -- Porosity tests Ferroxyl test Revetements métalliques - Essais de porosité Essai au ferroxyle ISO Reference number ISO 10309:1994(E) IS010309:1994(E) Foreword IsO (the International Organization for Standardization) is a worldwide federation of national standards bodies (isO member bodies).The work of preparing International Standards is normally carried out through IsO technicalcommittees.Eachmemberbodyinterestedinasubjectfor represented on that committee. International organizations, governmental and non-governmental, in liaison with iSO, also take part in the work. IsO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies forvoting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 10309 was prepared by Technical Committee ISO/TC107,Metallic and other inorganic coatings,Subcommittee SC 7, Corrosiontests. ISO 1994 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International OrganizationforStandardization CasePostale56·CH-1211Geneve20·Switzerland Printed in Switzerland ii INTERNATIONAL STANDARD ISO ISO10309:1994(E) Metallic coatings Porosity tests Ferroxyl test 1 Scope tom of discontinuities in metallic coatings migrate to treated test paper held in contact with the coating This International Standard specifies a method of re- surface. The base metal ions retained on the treated vealing pores or other discontinuities, when testing test paper form a blue-coloured marking or spot when metallic coatings, that are not visibly affected by the treated paper is subsequently immersed in a sol- ferricyanide and chloride ions during the test period ution of a ferricyanide indicator solution. and that are cathodic to iron and steel. This method is especially useful for thick, hard chromium coatings usedfor wearresistance. Reagents and materials NOTE 1With some coating materials a very thin layer is dissolved by the sodium chloride solution during a 10 min- 4.1 Purity ute application period (see 5.2.3). The impact of such dis- solution is that potential porosity, i.e. pores that have been All chemicals used shall be of a recognized analytical coveredoverbyverythinlayers,aresometimesre-exposed reagent grade and the water used shall be distilled or Experience has shown that such potential porosity is fre- deionized having a conductivity not greater than quently re-exposed during actual service. 20 μS/cm (see ISO 3696). 4.2 Preparation of the indicator solution 2 Normative reference The following standard contains provisions which, 4.2.1 Sodium chloride reagent through reference in this text, constitute provisions of this International Standard. At the time of publi- Dissolve 50 g of sodium chloride and 1 g of a non- cation, the edition indicated was valid. All standards ionic wetting agent in 1 litre of hot (90 C) water. are subject to revision, and parties to agreements Dissolve 50 g of gelatin or agar in the above men- based on this International Standard are encouraged tioned hot sodium chloride solution to provide gelling to investigate the possibility of applying the most re- properties. The solution will then gel upon cooling, but cent edition of the standard indicated below. Mem can be re-liquefied, for use, by heating it to 35 °C. bers of IEC and ISO maintain registers of currently NOTE 2A variety of non-ionic wetting agents is com- valid International Standards. mercially available. Is03696:1987,Waterforanalytical laboratoryuse Specification and test methods. 4.2.2 Ferricyanide reagent D