ASTM_F_21_-_14.pdf

Designation:F2114Standard Test Method forHydrophobic Surface Films by the Atomizer Test1This standard is issued under the fixed designation F21;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the detection of the presence ofhydrophobic(nonwetting)films on surfaces and the presenceof hydrophobic organic materials in processing environments.When properly conducted,the test will enable detection offractional molecular layers of hydrophobic organic contami-nants.On very rough or porous surfaces the sensitivity of thetest may be significantly decreased.1.2 The values stated in SI units are to be regarded as thestandard.The inch-pound values given in parentheses are forinformation only.1.3 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:2C813 Test Method for Hydrophobic Contamination on Glassby Contact Angle MeasurementD351 Classification for Natural Muscovite Block Mica andThins Based on Visual QualityD1193 Specification for Reagent WaterD2578 Test Method for Wetting Tension of Polyethylene andPolypropylene FilmsD5946 Test Method for Corona-Treated Polymer Films Us-ing Water Contact Angle MeasurementsD7334 Practice for Surface Wettability of Coatings,Sub-strates and Pigments by Advancing Contact Angle Mea-surementD7490 Test Method for Measurement of the Surface Tensionof Solid Coatings,Substrates and Pigments using ContactAngle MeasurementsF22 Test Method for Hydrophobic Surface Films by theWater-Break Test3.Terminology3.1 Definitions:3.1.1 hydrophilic,adjhaving a strong affinity for water;wettable.3.1.1.1 DiscussionHydrophilic surfaces exhibit zero con-tact angle with water.A sessile drop of water applied to thesurface will immediately spread out to form a film.3.1.2 hydrophobic,adjhaving little affinity for water;nonwettable.3.1.2.1 DiscussionHydrophobic surfaces exhibit contactangles between a sessile drop of water and the surfaceappeciably greater than zero.3.1.3 sessile drop,na drop of liquid sitting on the upperside of a horizontal surface.3.1.4 water-break,na break in the continuity of a film ofwater on a surface on removal from an aqueous bath or onremoval of a flowing water source from the surface.3.1.5 contact angle,nthe interior angle that a drop makesbetween the substrate and a tangent drawn at the intersectionbetween the drop and the substrate as shown in Fig.1;this isthe angle formed by a liquid at the three phase boundary wherea liquid,gas(air),and solid intersect.4.Summary of Test Method4.1 The atomizer test3is performed by subjecting the drysurface to be tested to a fine water spray.The interpretation ofthe test is based upon the pattern of wetting.In the absence ofhydrophobic films,the impinging water droplets will wet thesurface and spread immediately to form a continuous waterfilm.Contaminated areas having a surface tension lower thanwater will cause the water to bead up at that location.Mostcommon film contaminants such as oils,silicones,or fluoro-carbon greases have surface tensions significantly lower thanwater.In areas where these hydrophobic materials are present1This test method is under the jurisdiction of ASTM Committee E21 on SpaceSimulation and Applications of Space Technology and is the direct responsibility ofSubcommittee E21.05 on Contamination.Current edition approved Nov.1,2014.Published November 2014.Originallyapproved in 1962.Last previous edition approved in 2007 as F21 65(2007).DOI:10.1520/F0021-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Linford,H.B.,and Saubestre,E.B.,“A New Degreasing Evaluation Test:TheAtomizer Test,”ASTM Bulletin,May 1953,p.47.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 on the surface,the sprayed droplets will not wet the surface andspread but will tend to remain as fine droplets.5.Significance and Use5.1 The atomizer test as described in this test method israpid,nondestructive,and may be used for control and evalu-ation of processes for the removal of hydrophobic contami-nants.The test may also be used for the detection and controlof hydrophobic contaminants in processing environments.Forthis application,a surface free of hydrophobic films is exposedto the environment and subsequently tested.45.2 This test method is related to Test Method F22.This testmethod