ASTM_C_813_-_90_2014.pdf

Designation:C81390(Reapproved 2014)Standard Test Method forHydrophobic Contamination on Glass by Contact AngleMeasurement1This standard is issued under the fixed designation C813;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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the detection of hydrophobiccontamination on glass surfaces by means of contact anglemeasurements.When properly conducted,the test will enabledetection of fractions of monomolecular layers of hydrophobicorganic contaminants.Very rough or porous surfaces maysignificantly decrease the sensitivity of the test.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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:2D1193 Specification for Reagent Water3.Terminology3.1 Definitions:3.1.1 advancing anglethe largest angle observable when aliquid droplet is increased in size.3.1.2 hydrophilichaving a strong affinity for water;wet-table.3.1.2.1 DiscussionHydrophilic surfaces exhibit zero con-tact angles.3.1.3 hydrophobichaving little affinity for water;nonwet-table.3.1.3.1 DiscussionHydrophobic surfaces exhibit contactangles appreciably greater than zero:generally greater than 45for the advancing angle.3.1.4 receding anglethe smallest angle observable when aliquid droplet is decreased in size.3.1.5 sessile dropa drop of liquid sitting on the upper sideof a horizontal surface.3.1.5.1 DiscussionSee Fig.1.4.Summary of Test Method4.1 The contact angle test is performed by depositingdroplets of permanganate-distilled water or reagent water inaccordance with Specification D1193 on the surface to betested using a mounted hypodermic syringe,said dropletsbeing deposited in such a way,as described herein,as tomeasure the advancing contact angle.The measurements shallbe made by either of these two well-known methods:(1)viewing the sessile drop through a comparator microscopefitted with a goniometer scale with direct measurement of theangle;or(2)photographing the sessile drop and measuring theangle with a protractor.The interpretation of the measurementsis based on the fact that organic contamination on surfacesresults in contact angles appreciably higher than the near-zeroangles measured on clean surfaces or those contaminated byhydrophilic materials.5.Significance and Use5.1 The contact angle test is nondestructive and may be usedfor control and evaluation of processes for the removal ofhydrophobic contaminants.The test may also be used for thedetection and control of hydrophobic contaminants in process-ing ambients.For this application,a surface free of hydropho-bic films is exposed to the ambient conditions and is subse-quently tested.6.Interferences6.1 Loss of sensitivity may result from either of the follow-ing factors:6.1.1 The presence of hydrophilic substances on the surfaceto be tested,or in the water used for the test,or6.1.2 An unusually rough or porous surface.1This test method is under the jurisdiction of ASTM Committee C14 on Glassand Glass Products and is the direct responsibility of Subcommittee C14.02 onChemical Properties and Analysis.Current edition approved Oct.1,2014.Published October 2014.Originallyapproved in 1975.Last previous edition approved in 2009 as C813 90(2009).DOI:10.1520/C0813-90R14.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.Apparatus7.1 Low-Power Comparator Microscope(5 to 50),withgoniometer scale and light source for illumination of smalldrops.7.2 Camera,that can take photographs of the drop if thisalternative method is used.7.3 Protractor,to measure the angle if the alternativemethod is used.7.4 Hypodermic Syringe or Micrometer Buret,in a fixedmount.The needle of the syringe or the buret tip should be BDgage 20 to 26 or equivalent and should have a square-cut tip.7.5 Movable Platen,on which to mount the specimen whenviewing the drop in profile.8.Reagents and Materials8.1 Purity of WaterEither Type II reagent water in accor-dance with Specification D1193,or water distilled from a 3-g/Lpotassium permanganate solution is usually satisfactory.Thewater used must be free of hydrophobic and hydrophilicsubstances.To test the purity of the water for freedom fromhydrophobic