ASTM_D_1186_-_01.pdf

Designation:D 1186 01Standard Test Methods forNondestructive Measurement of Dry Film Thickness ofNonmagnetic Coatings Applied to a Ferrous Base1This standard is issued under the fixed designation D 1186;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1.Scope1.1 These test methods cover the nondestructive measure-ment of the dry film thickness of nonmagnetic coatings appliedover a ferrous base material using commercially available testinstruments.The test methods are intended to supplementmanufacturers instructions for the manual operation of thegages and are not intended to replace them.They cover the useof instruments based on magnetic measuring principles only.Test Method A provides for the measurement of films usingmechanical magnetic pull-off gages and Test Method B pro-vides for the measurement of films using magnetic electronicgages.1.2 These test methods are not applicable to coatings thatwill be readily deformable under the load of the measuringinstruments,as the instrument probe must be placed directly onthe coating surface to take a reading.1.3 The values given in SI units of measurement are to beregarded as the standard.The values in parentheses are forinformation only.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint,Varnish,Conversion Coatings,andRelated Coating Products2D 823 Practices for Producing Films of Uniform Thicknessof Paint,Varnish,and Related Products on Test Panels22.2Steel Structures Painting Council Standard:SSPC-PA2 Measurement of Dry Paint Thickness with Mag-netic Gages3TEST METHOD AMAGNETIC PULL-OFF GAGES3.Summary of Test Method3.1 Instruments complying with this test method measurethickness by using a spring calibrated to determine the forcerequired to pull a magnet from a ferrous base coated with anonmagnetic film.The instrument must be placed directly onthe coating surface to take a reading.3.2 The attractive force of the magnet to the substrate variesinversely with the thickness of the applied film.The springtension required to overcome the attraction of the magnet to thesubstrate is shown on the instrument scale as the distance(inmils or microns)between the magnet and the substrate.4.Significance and Use4.1 Many coating properties are markedly affected by thethickness of the dry film such as adhesion,corrosion protec-tion,flexibility,and hardness.To be able to compare resultsobtained by different operators,it is essential to know filmthickness.4.2 Most protective and high performance coatings areapplied to meet a requirement or a specification for the dry-filmthickness of each coat,or for the complete system,or both.Coatings must be applied within certain minimum and maxi-mum thicknesses to fill their expected function.In addition topotential performance deficiencies,it is uneconomical to applymore material than necessary when coating large areas.Thistest method is used to measure film thickness of coatings onferrous metals.5.Apparatus5.1 Permanent Magnet,small,either attached directly to acoil spring(“pencil”gage)or to a horizontal lever arm that isattached to a helical spring(“dial-type”gage).Increasing forceis applied to the magnet by extending the coil spring in the firstcase or turning a graduated dial that coils the helical spring inthe second.The readings obtained are shown directly on theinstrument scale.5.2 Coating Thickness Standards,with assigned valuestraceable to national standards are available from severalsources,including most manufacturers of coating thicknessgages.1These test methods are under the jurisdiction ofASTM Committee D1 on Paintand Related Coatings,Materials,and Applications and are the direct responsibilityof Subcommittee D01.23 on Physical Properties of Applied Paint Films.Current edition approved July 10,2001.Published September 2001.Originallypublished as D 1186 51.Last previous edition D 1186 93.2Annual Book of ASTM Standards,Vol 06.01.3Available from SSPC:The Society for Protective Coatings,40 24th St.,SixthFloor,Pittsburgh,PA 152224643(see www.sspc.org).1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-2959,United States.6.Test Specimens6.1 When this test method is used in the field,the specimenis the coated structure or article on which the thickness is to beevaluated.6.2 For laboratory use,apply the material to be tested topanels of similar roughness,shape,t