ASTM_D_5532_-_94_1999.pdf

Designation:D 5532 94(Reapproved 1999)Standard Specification forMicaceous Iron Oxide Pigments for Paint1This standard is issued under the fixed designation D 5532;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.1.Scope1.1 This specification covers the requirements and methodsof test for lamellar iron oxide pigments,commonly calledmicaceous iron oxide,used primarily in protective coatings forsteel.This standard is related to ISO 10601 and AustralianStandard 2855-covering both specifications and methods oftest.A companion test method for lamellar(thin film)contentis included.This specification covers two types of micaceousiron oxide.1.2 The following hazard caveat pertains only to the testmethod portion,Section 9,of this specification:This standarddoes not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility of the user of thisstandard to establish appropriate safety and health practicesand determine the applicability of regulatory limitations priorto use.2.Referenced Documents2.1 ASTM Standards:D 50 Test Methods for Chemical Analysis of Yellow,Or-ange,Red,and Brown Pigments Containing Iron andManganese2D 280 Test Methods for Hygroscopic Moisture(and OtherMatter Volatile Under the Test Conditions)in Pigments2D 1030 Test Method for Fiber Analysis of Paper and Paper-board3D 1208 Test Methods for Common Properties of CertainPigments22.2Other Standards:ISO-10601 Micaceous Iron Oxide Pigments for PaintsSpecifications and Methods of Test42855-1986,Paint and Related MaterialsMicaceous IronOxide Pigment52.3 ASTM Adjuncts:Three photographs of two grades of micaceous iron oxidepigment63.Terminology3.1 Definitions:3.1.1 lamellar particlesthin flat particles.3.1.2 micaceous,lamellarsimilar to the structure of mica.3.1.3 micaceous or lamellar iron oxide(MIO)a refinedmineral ore(also known as specular haemetite)or a manufac-tured product,consisting of iron(III)oxide(Fe2O3).It is greyin color with a metallic sheen and a lamellar form.4.Significance and Use4.1 The primary use of lamellar iron oxide is in protectivecoatings for steel and for optimum performance the pigmentshould have a high content of thin,flake-like particles.Theprotective action is ascribed to close packing of the pigmentplatelets within the paint film forming overlapping layers thatlie roughly parallel to the substrate.This impedes penetrationof corrosion stimulants,reduces ultraviolet degradation of thebinder,improves film strength,reduces polymer swelling,andminimizes blistering.For less critical requirements,micaceousiron oxide with lower content of thin flakes may be acceptable.Therefore in this specification,micaceous iron oxide pigmentsare classified into two groups according to their thin flakecontent as determined by microscopic examination(see Sec-tion 9).When the proportion of lamellar particles is 6550 to 65Maximum retained on 150-mesh(106-m),U.S.standard seive No.1400.10.17.Sampling7.1 Two samples shall be taken at random from differentpackages from each lot,batch,days pack or other unit ofproduction in a shipment.When no markings distinguishingunits of production appear,samples to be tested shall be takenfrom lot sizes agreed upon between the buyer and the producer.At the option of the purchaser,the samples may be testedseparately or,after blending the samples from the sameproduction unit in equal quantities,tested as a compositesample.TEST FOR LAMELLAR CONTENT8.Reagent8.1 Reagentrefined linseed oil.9.Procedure9.1 Place a few milligrams of a representative sample of thedry pigment on the glass slide.Add a few drops of refinedlinseed oil and gently incorporate the pigment into the oil usingthe glass rod,spreading the mixture thinly and evenly.Placethe cover slip over the pigment/oil dispersion and position onthe microscope stage.9.2 Spread a few milligrams of the sample of the drypigment on the glass slide and examine it without adding anylinseed oil as follows:Adjust the light intensity below the slideto the highest practical level.Focus sharply at 200 3 magni-fication and scan the slide until a field of view is obtainedwhich is considered to be representative and in which at least50 particles can be seen.9.3 Thin-flake lamellar iron-oxide particles will appear assharply defined red translucent platelets while thicker particleswill appear as black shapes.Platelets 65IIProportion of red particles50 to 65Non-lamellarProportion ofblackparticles509.5 If the thin flake content is not obvious,count the numberof red and black particles in a group of at least 50 particles.Aframe-image device(see Note 1)will assist this operation.Repeat the count on a duplicate slide and calculate the averagepercentage of red particles.To assist counting,it may be usefulto use an