1、Designation: D 5895 03Standard Test Methods forEvaluating Drying or Curing During Film Formation ofOrganic Coatings Using Mechanical Recorders1This standard is issued under the fixed designation D 5895; the number immediately following the designation indicates the year oforiginal adoption or, in th
2、e 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 These test methods describe the determination of severalstages and the rate of dry-fi
3、lm formation of organic coatingsusing straight line and circular mechanical drying-time record-ing devices. The use of mechanical recorders is valuable incomparing the drying behavior of coatings of the same generictype, allowing that one coating may form a gel or resist tearingat a faster rate than
4、 another.1.2 Drying time measured using the mechanical recordersmay differ from those found using conventional methods, suchas Test Method D 1640 or ISO 1517.1.3 The values stated in SI are to be regarded as thestandard. The values given in parentheses are provided forinformation only.1.4 This stand
5、ard 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 AS
6、TM Standards:D 823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish and Related Products on Test Panels2D 1005 Test Methods for Measurement of Dry-Film Thick-ness of Organic Coatings Using Micrometers2D 1640 Test Method for Drying, Curing, or Film Formationof Organic Coatings at R
7、oom Temperature2D 3924 Specification for Standard Environment for Condi-tioning and Testing Paint, Varnish, Lacquers, and RelatedMaterials2D 3925 Practice for Sampling Liquid Paints and RelatedPigmented Coatings22.2 ISO StandardISO 1517 Drying Time Using Ballotini33. Terminology3.1 Descriptions of T
8、erms Specific to This Standard:3.1.1 dry-hard time, nThe dry-hard condition is reachedusing mechanical recorders when the drying and curing, orboth, reactions have proceeded sufficiently that the film is notdisplaced nor is any noticeable mark left by pinching the panelsbetween the thumb on the film
9、 and forefinger with a relativelystrong force. In these test methods, the dry-hard time is reachedwhere the stylus has risen out of the film and rides on thesurface, leaving only a mark without disrupting the body of thefilm (see Fig. 1 and Fig. 2).3.1.2 dry-through time, nThe dry-through condition
10、isreached when the film has solidified so completely that a large,twisting force can be applied without distorting the film. Inthese test methods, the dry-through time is reached when thestylus no longer left any visible mark on the film (see Fig. 1and Fig. 2).3.1.3 set-to-touch time, nThe set-to-to
11、uch condition isreached when the film has solidified sufficiently, by solventevaporation or chemical reaction, or both, that it not longerflows nor sticks to a finger that lightly touches it. In these testmethods, the set-to-touch time is reached where a pear-shapeddepression appears in the film whe
12、n the film stops flowing overthe path of the recorders stylus and leaves a track in the filmrevealing the glass substrate (see Fig. 1 and Fig. 2).3.1.4 tack-free time, nThe tack-free condition is reachedusing mechanical recorders when the film surface has dried orcured (see set-to-touch time) so tha
13、t the film does not adhere tovery light objects placed on it. In these test methods, thetack-free time is reached where the continuous track in the filmceases and the stylus starts to tear the film or leave aragged/sharp-edged grove as it first begins to climb over thefilm (see Fig. 1 and Fig. 2).NO
14、TE 1The above descriptions are typical for coatings that do notskin over during curing. Any coating which exhibits skinning, such as twopack epoxies or polyurethane coatings, will show a very different track1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coat
15、ings, Materials, and Applications and are the directresponsibility of Subcommittee D01.23 on Physical Properties of Applied PaintFilms.Current edition approved May 10, 2003. Published July 2003. Originallyapproved in 1996. Last previous edition approved in 2001 as D 5895 01e1.2Annual Book of ASTM St
16、andards, Vol 06.01.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.where the stylus tears the surface of t
17、he film, leaving diamond orkite-shaped patterns.4. Summary of Test Methods4.1 In Test Method A (Straight Line Recorder), the coatingis applied to glass strips approximately 300 by 25 mm (12 by1 in.). The drying time recorder is immediately placed on thewet film and the stylus lowered onto the wet co
18、ating. The stylusmoves across the glass strip at a selected constant speed.4.2 In Test Method B (Circular Recorder), the coating isapplied to glass plates approximately 6 in. by 6 in. (150 by 150mm). The drying time recorder is immediately placed on thewet film and a stylus is moved in a 360 arc at
19、a selectedconstant speed.5. Significance and Use5.1 The drying times of a coating are significant in deter-mining when a freshly painted room, floor or stair may be putback in use or a coated article handled or packaged. Slowdrying may result in dirt pick-up or, on an exterior surface,moisture may c
20、ause a nonuniform appearance.5.2 These test methods are used to determine the variousstages of drying or curing in the dry-film formation of organiccoatings using mechanical devices for the purpose of compar-ing types of coatings or ingredient changes, or both. Toevaluate the stages of drying in a q
21、uantitative manner, use ofinstrumentation under environmental controlled conditions isstrongly recommended. These devices also offer a method ofdetermining drying characteristics of coatings that can not beascertained within the standard 8-h work day.5.3 When evaluating drying characteristics of bak
22、ing sys-tems, the circular drying time devices offer a method todetermine quantitatively drying times of coatings at roomtemperature and elevated conditions. Maximum temperatureswould be limited by considerations such as the affect oftemperature on the motor lubrication or structural componentsof th
23、e device.5.4 The straight line drying time devices offer a method todetermine quantitatively drying times of coatings tested simul-taneously using one recorder.5.5 This method is useful in comparing the behavior ofcoatings during drying of the same generic type. Determinationof actual drying times s
24、hould be conducted following proce-dures outlined in Test Method D 1640 or ISO 1517.6. Coatings and Recommend Film Thicknesses6.1 Whenever tests are to be performed on coatings notlisted in Table X1.1, there should be a prior agreement betweenthe purchaser and seller as to the substrate, film thickn
25、ess,application method, and conditions for testing the specificcoating involved.6.2 Tests should be carried out at a practical viscosity underwhich the coating can be applied at the proper film thicknesswith resultant good flow and leveling properties.6.3 Films to be tested should have practical thi
26、cknessescommensurate with those expected under actual usage for thetype under test.7. Test Conditions7.1 Air Dry Coatings, conduct all tests in a well ventilatedroom, free from direct drafts, dust, laboratory fumes, and underdiffused light. Make all measurements at a temperature of 23 62C and 50 6 5
27、 % relative humidity in accordance withSpecification D 3924. For baking systems, conduct all tests ina forced draft oven at controlled temperatures within the limitsof the drying time device.7.2 Light ConditionsIllumination of air dry films duringthe entire drying test period should be about 270 lx
28、(25 fc) fromnormal laboratory or sky sources, never from direct sunlight orother sources high in nonvisible radiant energy.8. Preparation of Test Specimens8.1 All test specimens shall be prepared and tested by oneoperator properly skilled in the methods to be used. ConductNOTE 1The above figure repr
29、esents a typical track of a coating thatdoes not skin over during curing. Any coating which exhibits skinning,such as two pack epoxies or polyurethane coatings, will show a verydifferent track where the stylus tears the surface of the film, leavingdiamond or kite-shaped patterns.FIG. 1 Stages of Dry
30、ing Using Straight Line Drying TimeRecordersFIG. 2 Stages of Drying Using Circular Time Drying RecordersD5895032testing at least in duplicate. Sampling shall be conducted inaccordance with procedures outlined in Practice D 3925.8.2 Apply the test materials to clean glass panels or otherspecific subs
31、trates of suitable dimensions agreed upon betweenthe purchaser and the seller.NOTE 2Ground-glass plates may be more suitable for certain types ofcoatings that have a tendency to crawl, such as low-viscosity drying oils.Suitable plates can be prepared by roughening the surface of polishedglass by gri
32、nding a paste of silicon carbide (grit 1-F) and water betweentwo glass plates.8.3 Cast the test films preferably with an appropriate filmapplicator for the recommended dry film thickness as indicatedin Table X1.1. When a suitable applicator is not available or ithas been agreed to apply the film in
33、some other manner, thevarious conventional or automatic methods of spray, dip, flowand brush application may be used, provided dry film thick-nesses conform to the requirements in Table X1.1. See PracticeD 823 for a descriptions of the spray and dip methods ofapplication.8.4 Measure the dry film thi
34、ckness of the test films with anappropriate film thickness gage.Amicrometer or dial indicator,as described in Test Methods D 1005, has been found suitablefor glass substrates.TEST METHOD ASTRAIGHT LINE DRYING TIME9. Apparatus9.1 Straight Line Drying Time Recorder, consists of mul-tiple styli 2 mm (0
35、.08 in.) in diameter with rounded tips, beingdrawn over multiple parallel-coated glass panels typicallymeasuring 300 by 25 mm (12 by 1 in.). The stylus armgenerally comes with 5-g brass weights that may be added toapply greater pressure on the needles and thus record throughdrying. Other weights can
36、 be adapted as agreed upon betweenpurchaser and seller. Speed can be varied to cover dryingperiods from 6, 12 and 24 h.10. Procedure10.1 Apply the coating to the glass plates or strips. Recordtime of application. Immediately attach the glass plates orstrips to the instrument, and lower the stylus ca
37、rrier so that thestylus carrier is at the starting position. Lower the clean stylusgently into position on the strip. Always assure that the tip ofthe styli is clean and free from dried paint from previous testsprior to use. Switch on the motor and the stylus will be drawnalong the glass strip by th
38、e carrier.10.2 Always mark the point on the glass strip where thestylus is first lowered into the wet film by use of a marker penor similar method. This will aid measurement of times alongthe strip during the assessment stage as it is often not obviousat what point the track starts, as paint flows b
39、ack into thegroove.10.3 After drying, evaluate the glass plates or strips todetermine the stages of drying time as shown in Fig. 1. The useof magnification (73 etc.) will enhance the evaluation.TEST METHOD BCIRCULAR DRYING TIME11. Apparatus11.1 Circular Drying Time Recorder, consisting of a motortha
40、t is mounted on a rubber-tipped tripod. The motor shaft isoriented in the vertical, with a pivotal arm assembly attached tothe shaft to operate a counter-poised vertical stylus consistingof a teflon stylus approximately 10 mm (38 in.) in diameter.The teflon stylus, typically under a weighted load of
41、 12 g,scribes an arc in the drying film. The arm assembly includes acounter weight to permit adjusting the pressure on the needle tonear zero. The stylus is moved in a 360 arc at a selectedconstant speed. Recorders are available to cover various dryingtimes, such as 1, 6, 12 or 24 h.11.2 TemplateA t
42、ransparent template with scale gradua-tions, corresponding to the particular motor speed, is used fortiming the various stages of drying revealed by differencesobserved in the scribed pattern.12. Procedure12.1 Panel PreparationPrepare specimens following pro-cedures outlined in 8.1 through 8.4. Glas
43、s plates or panels,about 150 by 150 mm (6 by 6 in.), are used for the determi-nation of drying times using this recording device.12.2 Apply the coating to the glass plates or panels. Recordtime of application. Immediately attach the glass plates orpanels to the instrument, and lower the clean stylus
44、 gently intoposition on the panel. Always assure that the tip of the stylus isclean and free from dried paint from previous tests prior to use.Switch on the motor so the stylus is drawn along the glasspanels.12.3 Always mark the point where the stylus is first loweredinto the wet film by use of a ma
45、rker pen or similar method. Thiswill aid measurement of times along the track during theassessment stage as it is often not obvious at what point thetrack starts, as paint flows back into the groove.12.4 After drying, evaluate the glass plates or panels todetermine the stages of drying time as shown
46、 in Fig. 2. The useof magnification (73 etc.) will enhance the evaluation.13. Report13.1 Report the following information:13.1.1 Test results of drying time determinations,13.1.2 Type of coating material used,13.1.3 Method of application,13.1.4 Film thickness used,13.1.5 Type of mechanical drying re
47、corder used, and13.1.6 All applicable conditions that deviated from thestandards as outlined or special conditions or tests used.14. Precision and Bias414.1 PrecisionIn an interlaboratory study of these testmethods, drying times were recorded in four laboratories forfour drying stages of four differ
48、ent coatings varying widely in4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D011119.D5895033drying characteristics. The intralaboratory coefficient of varia-tion was found to be 20.35 % with 56 df and the interlaboratorycoeffi
49、cient 20.35 % with 42 df with no values discarded. Basedon these coefficients, the following criteria should be used forjudging at the 95 % confidence level, the acceptability ofresults:14.1.1 RepeatabilityTwo single results obtained by thesame operator at different times should be considered suspectif they differ by more than 57.7 % of their mean value.14.1.2 ReproducibilityTwo results, each the mean of tworepeat determinations, obtained by operators in different labo-ratories should be considered suspect if they differ by morethan 58.15 % of their mean value.14.
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