1、Designation: D5895 13Standard Test Methods forEvaluating Drying or Curing During Film Formation ofOrganic Coatings Using Mechanical Recorders1This standard is issued under the fixed designation D5895; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、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 These test methods describe the determination of severalstages and the rate of dry-film
3、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 an
4、other.1.2 Drying time measured using the mechanical recordersmay differ from those found using conventional methods, suchas Test Method D1640 or ISO 9117-3 (formerly ISO 1517).1.3 The values stated in SI are to be regarded as thestandard. The values given in parentheses are provided forinformation o
5、nly.1.4 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. Referenc
6、ed Documents2.1 ASTM Standards:2D823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD1640 Test Methods for Drying, Curing, or Film Formationof Organi
7、c Coatings at Room TemperatureD3924 Specification for Environment for Conditioning andTesting Paint, Varnish, Lacquer, and Related MaterialsD3925 Practice for Sampling Liquid Paints and RelatedPigmented Coatings2.2 ISO Standard:ISO 9117-3 Drying testsSurfacedrying test using ballo-tini33. Terminolog
8、y3.1 Definitions of Terms 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
9、the thumb on the film and forefinger with a relativelystrong force.3.1.1.1 DiscussionIn these test methods, the dry-hard timeis reached where the stylus has risen out of the film and rideson the surface, leaving only a mark without disrupting the bodyof the film (see Fig. 1 and Fig. 2).3.1.2 dry-thr
10、ough time, nthe dry-through condition isreached when the film has solidified so completely that a large,twisting force can be applied without distorting the film.3.1.2.1 DiscussionIn these test methods, the dry-throughtime is reached when the stylus no longer left any visible markon the film (see Fi
11、g. 1 and Fig. 2).3.1.3 set-to-touch time, nThe set-to-touch 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.3.1.3.1 DiscussionIn these test methods, the set-to-t
12、ouchtime is reached where a pear-shaped depression appears in thefilm when the film stops flowing over the path of the recordersstylus and leaves a track in the film revealing the glasssubstrate (see Fig. 1 and Fig. 2).3.1.4 tack-free time, nthe tack-free condition is reachedusing mechanical recorde
13、rs when the film surface has dried orcured (see set-to-touch time) so that the film does not adhere tovery light objects placed on it.3.1.4.1 DiscussionIn these test methods, the tack-freetime is reached where the continuous track in the film ceases1These test methods are under the jurisdiction of A
14、STM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.23 on Physical Properties of Applied PaintFilms.Current edition approved June 1, 2013. Published June 2013. Originallyapproved in 1996. Last previous edition approved in 2
15、008 as D5895 03 (2008).DOI: 10.1520/D5895-13.2For 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.3Available from
16、American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1and the stylus starts to tear the film or leave a ragged/sharp-edged grove
17、as it first begins to climb over the film (see Fig. 1and Fig. 2).NOTE 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 trackwhere the stylus tears the
18、surface of the 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 ont
19、o the wet coating.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
20、360 arc at 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,moi
21、sture may cause 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 dr
22、ying in a quantitative 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 characteris
23、tics of bakingsystems, 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 compon
24、entsof the 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 dryin
25、g times should be conducted following proce-dures outlined in Test Method D1640 or ISO 9117-3.6. 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, f
26、ilm thickness,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 pra
27、ctical thicknessescommensurate 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
28、and 50 6 5 % relative humidity in accordance withSpecification D3924. For baking systems, conduct all tests in aforced draft oven at controlled temperatures within the limits ofthe drying time device.NOTE 1The above figure represents a typical track of a coating thatdoes not skin over during curing.
29、 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 Drying Using Straight Line Drying Time Record-ersFIG. 2 Stages of Drying Usi
30、ng Circular Time Drying RecordersD5895 1327.2 Light ConditionsIllumination of air dry films duringthe entire drying test period should be about 270 lx (25 fc) fromnormal laboratory or sky sources, never from direct sunlight orother sources high in nonvisible radiant energy.8. Preparation of Test Spe
31、cimens8.1 All test specimens shall be prepared and tested by oneoperator properly skilled in the methods to be used. Conducttesting at least in duplicate. Sampling shall be conducted inaccordance with procedures outlined in Practice D3925.8.2 Apply the test materials to clean glass panels or othersp
32、ecific substrates 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 polishedg
33、lass by grinding 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 t
34、he film in 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 PracticeD823 for a descriptions of the spray and dip methods ofapplication.8.4 Measure the dr
35、y film thickness of the test films with anappropriate film thickness gage.Amicrometer or dial indicator,as described in Test Methods D1005, has been found suitablefor glass substrates.TEST METHOD ASTRAIGHT LINE DRYING TIME9. Apparatus9.1 Straight Line Drying Time Recorder, consists of multiplestyli
36、2 mm (0.08 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 weig
37、hts can 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 st
38、ylus carrier 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 stri
39、p by the 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
40、flows back 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 (7 etc.) will enhance the evaluation.TEST METHOD BCIRCULAR DRYING TIME11. Apparatus11.1 Circular Drying Time Recorder, consisting of a mo
41、torthat 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 l
42、oad of 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 Templ
43、ateA transparent template with scalegraduations, corresponding to the particular motor speed, isused for timing the various stages of drying revealed bydifferences observed in the scribed pattern.12. Procedure12.1 Panel PreparationPrepare specimens following pro-cedures outlined in 8.1 through 8.4.
44、Glass 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 st
45、ylus 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
46、 marker 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 sho
47、wn in Fig. 2. The useof magnification (7 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 r
48、ecorder used, and13.1.6 All applicable conditions that deviated from thestandards as outlined or special conditions or tests used.D5895 13314. Precision and Bias414.1 PrecisionIn an interlaboratory study of these testmethods, drying times were recorded in four laboratories forfour drying stages of f
49、our different coatings varying widely indrying characteristics. The intralaboratory coefficient of varia-tion was found to be 20.35 % with 56 df and the interlaboratorycoefficient 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 re
