1、Designation: D 4941 06Standard Practice forPreparing Drawdowns of Artists Paste Paints1This standard is issued under the fixed designation D 4941; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number
2、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 practice covers the production of uniform films ofartists tube paints and other nonflowing pigmented paintsusing paint applicators desig
3、ned for less viscous paints.1.2 Information on how to achieve opaque specimens fromthese paints is included.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety conc
4、erns, 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:2D16 Terminology for Paint, Related Coat
5、ings, Materials,and ApplicationsD 4838 Test Method for Determining the Relative TintingStrength of Chromatic PaintsE 1164 Practice for Obtaining Spectrometric Data forObject-Color Evaluation3. Terminology3.1 DefinitionsSee Terminology D16 for definitions ofterms used in this practice.3.2 Definitions
6、 of Terms Specific to This Standard:3.2.1 drawdown, na layer of paint deposited on a sub-strate by use of a drawdown bar for the evaluation of paintcharacteristics.3.2.2 drawdown bar, na metal applicator with a specifiedgap designed to deposit a wet paint film uniformly on aspecified test panel (for
7、 example, an opacity chart) or othersubstrate.4. Summary of Practice4.1 The paint is spread over the area of the test panel to becovered by the drawdown and the bar is pulled down withpressure just sufficient to avoid lifting of the bar from the chartsurface.4.2 Test panels are allowed to dry in a d
8、ust-free environ-ment.4.3 If complete hiding (opacity) is needed and not producedby a single paint film, a second film is applied at a 90 angle tothe first. If required, additional layers may be applied using anarrower drawdown bar.5. Significance and Use5.1 Quality standards for artists paints requ
9、ire the evalua-tion of various appearance characteristics of paint films.Tinting strength determination (Test Method D 4838) specifi-cally requires the preparation of drawdowns for colorimetricmeasurement. Other evaluations such as color designation,transparency, gloss, and color difference measurem
10、ents alsorequire drawdown samples.5.2 Artists tube paints have a paste consistency that makesthe use of traditional film application methods difficult, espe-cially for drying oil paints.5.3 Artists paints vary in two properties important to thepreparation of films, that is, transparency and drying t
11、ime.Colorimetric determination and some other types of evaluationrequire paint specimens that completely hide the substrate.Very transparent paints require such a thick film to producecomplete hiding that drying times is excessively long or thespecimen surface is blemished. When complete hiding isne
12、cessary, this practice is designed to provide opaque filmswithout these defects through application of a series of thinfilms.6. Apparatus6.1 Drawdown Bars, two, of different widths with a clear-ance of 0.152 mm (0.006 in.). Recommended widths are 7.6cm (3 in.) and 15.2 cm (6 in.). The second bar is
13、required toprepare drawdowns with more than two layers. Wire wounddrawdown bars have been found to be unsuitable.6.2 Drawdown Charts, sealed paper type, half black andhalf white if transparency is being evaluated or opacity isnecessary.1This practice is under the jurisdiction of ASTM Committee D01 o
14、n Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.57 on Artists Paints and Related Materials.Current edition approved April 1, 2006. Published April 2006. Originallyapproved in 1989. Last previous edition approved in 2004 as D 4941 89 (2004)
15、.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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box
16、 C700, West Conshohocken, PA 19428-2959, United States.7. Procedure7.1 Attach chart to a firm, smooth, level plane surface usingtape, a vacuum plate, or a clamp. Label the chart with theidentity of the specimen and other data as required.7.2 Mix paint sample thoroughly using two spatulas. Tubepaints
17、 that have separated should be expelled completely andmixed.NOTE 1The use of coated freezer wrapping paper as a mixing surfacesimplifies clean up. The same paper can be used for weighing specimenswhen required as in the tinting strength determination (Test MethodD 4838).7.3 Using a spatula, spread t
18、he paint, in a thickness exceed-ing the bars gap clearance, over the entire area to be coveredby the drawdown. Do not cover the area to be contacted by thesupporting feet of the wider of the two bars. Starting at the topof the chart and using the wider bar, draw the bar down overthe paint in an even
19、 motion applying sufficient pressure toensure that the resistance of the viscous paint does not raise thefeet of the bar from the surface. When using oil paints themotion should be slow enough to allow for the high viscosity.Acrylic paints, which have short drying times, should beapplied immediately
20、 after mixing to avoid premature filmformation.7.4 After drying in a horizontal position for 15 min,specimens may be hung in a vertical position in a dust-free areato complete the drying. Allow 24 h for acrylic and alkyd paintsand 48 h or longer for oil paints until dry to touch.7.5 Examine the spec
21、imen for surface defects and discard ifunacceptable.7.6 If complete hiding is required, compare, either visuallyor instrumentally, the lightness of the paint on the black portionof the chart with that on the white. For instrumental evaluation,follow the procedures given in Practice E 1164 to determi
22、neCIE Y for each portion, then calculate the contrast ratio of thepaint film on the two portions of the chart (CIE Yblack/CIEYwhite). A contrast ratio of 0.98 or higher is considered opaque.7.6.1 If opacity is not sufficient, rotate the chart through a90 angle and deposit a second film using the wid
23、er bar torepeat the procedure in 7.3 through 7.5. If additional layers arerequired, repeat this sequence using the narrower bar. Becareful each time that the feet of the drawdown bar ride on thesurface of the combined lower layers. See Fig. 1 and Fig. 2.NOTE 2The most transparent paints studied were
24、 found to requirethree coats; however, in some instances, such as with alizarin crimson oilpaint, it may not be practical to obtain complete hiding.8. Keywords8.1 artists paint; drawdown; paint specimensFIG. 1 Preparation for DrawdownFIG. 2 Three Overlapping DrawdownsD4941062ASTM International takes
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26、onsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addresse
27、d to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the
28、address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D4941063
