1、Designation:D 1955 85(Reapproved 1995)Standard Test Method forGel Time of Drying Oils1This standard is issued under the fixed designation D 1955;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 pa
2、rentheses 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 This test method covers the determination of the geltime of tung oil,
3、oiticica oil,and,with modification oftemperature,other oils having gelling characteristics.1.2 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
4、 and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:E 1 Specification for ASTM Thermometers23.Terminology3.1 Definition:3.1.1 gel time,of a drying oilthe time required for the oilto form a solid gel under specified conditions of temperatu
5、re.4.Significance and Use4.1 The gel time of an oil at elevated temperature is anindication of its drying characteristics.Oils that have a highdegree of unsaturation are classed as drying oils.Oils in whicha high percentage of this unsaturation is conjugated dry thefastest.4.2 At elevated temperatur
6、es,the conjugated oils will forma gel;therefore this test method can be used to detectadulteration in highly conjugated oils such as tung and oiticicaoil,whereas unconjugated oils do not show a sharp gel point.The method is empirical in nature since the gel time must becompared to a known standard.5
7、.Apparatus5.1 The apparatus shall be assembled as shown in Fig.1 andshall consist of the following:5.1.1 BathA 1000-mL,tall-form beaker,containing ahydrogenated oil or other suitable liquid to a depth of 110 mm.The beaker shall be covered with a Monel,aluminum,orstainless steel support plate for tes
8、t tubes and thermometer.5.1.2 Glass Rods,approximately 170 mm in length.5.1.3 Test Tubes,150 by 16 mm with a mark to designate the5-mLlevel.Each tube shall be closed with a cork having a holethrough which a 3-mm glass rod can move freely.5.1.4 ThermometerAn ASTM Pensky-Martens High-Range Thermometer
9、 having a range from 90 to 370C and1This test method is under the jurisdiction of ASTM Committee D-1 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.32 on Drying Oils.Current edition approved May 31,1985.Published July 1985.Originallypublis
10、hed as D 1955 58 to replace Sections 4551 of D 555 58.Last previousedition D 1955 61(1984).2Annual Book of ASTM Standards,Vol 14.03.A 1000-mL,tall-form beaker,90 mm in diameter by 190 mm in heightB support plate about 65 mm in width,made of monel metal,aluminum,orstainless steelC test tubes,150 mm b
11、y 16 mm,with cork stoppersD 5 mL of reference standard oilE thermometer,range 90 to 370CF glass rods 3 mm in diameterG guide to prevent cover from slippingFIG.1 Apparatus for Gel Time Test1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.NO
12、TICE:This standard has either been superceded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.conforming to the requirements for Thermometer 10C asprescribed in Specification E 1.6.Procedure6.1 Heat the bath to 300 6 1C(Note 1 and Note
13、 2).Whenthe bath temperature is 300C and rising slowly,insert the tubecontaining 5 mL of the oil to be tested and another tubecontaining 5 mL of an oil of known behavior.Note the time.Within 2 min the bath temperature will have fallen to 288 61C(Note 3),at which point it should be maintained as clos
14、elyas possible for the duration of the test.NOTE1The recent change in immersion and running temperature forthis test was made to compensate for the change made in the type ofthermometer used.It is particularly important to use the specified ASTMThermometer 10C.NOTE2No stirrer shall be used in the ba
15、th.A screen around the bathenables the temperature to be reached and maintained more easily.Whenthe bath becomes discolored and viscous it should be renewed,as heatingbecomes irregular when a tarry and viscid state is reached.NOTE3The test may be run at a higher temperature for use withdehydrated ca
16、stor oil and other gelling oils where the gel times at 288Care excessively long.Include the temperature of the test in the report inthese cases.6.2 When the tubes have been in the bath 9 min,raise theglass rods at intervals of 15 s.Note the time when the oil isfirmly set.This is the point when the oil becomes stiff enoughthat the entire tube and contents may be raised by the rod.Record the elapsed time for the test oil and the standard.If thestandard deviates more than 30 s from the assigned val
