1、Designation: D 7072 04Standard Practice forEvaluating Accelerated Efflorescence of Latex Coatings1This standard is issued under the fixed designation D 7072; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. 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 practice covers the evaluation of the degree towhich a latex paint resists the formation of efflorescence andalkali burnout o
3、n the exposed paint surface.1.2 This practice is designed primarily to relate efflores-cence originating in the substrate to the deposit appearing onthe surface of latex paints. This practice relates chiefly to thepainting of masonry-type substrates such as concrete block,brick, mortar, stucco, pour
4、ed concrete and similar materials.1.3 The values in SI units are to be regarded as the standard.The values in parenthesis are for information only.1.4 This method does not purport to address all of the safetyconcerns, if any, associated with its use. It is the responsibilityof whoever uses this stan
5、dard to consult and establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1475 Test Method for Density of Paint, Varnish, Lacquerand Related ProductsD 1734 Practice for Making Cementitou
6、s Panels for TestingCoatingsD 4585 Practice for Testing Water Resistance of CoatingsUsing Controlled CondensationD 5068 Practice for Preparation of Paint Brushes for Evalu-ation3. Terminology Terminology (Specific to this Practice)3.1 Definitions of Terms Specific to This Standard:3.1.1 efflorescenc
7、e, nthe deposition of soluble salts on theexposed paint surface. Efflorescence is characterized by a lightcolored, nonuniform, powdery incrustation which detractsfrom the paint film appearance. The discoloration occurs whensoluble salts in the substrate or paint migrate to the surface bythe leaching
8、 and evaporating action of the water carrier. Theefflorescence originating within the substrate is that with whichthis method is concerned.3.1.2 alkali burnout, nthe premature fading or decompo-sition of paints that are sensitive to the high pH of the substrate.The high alkaline content of the subst
9、rate can alter the color.4. Summary of Practice4.1 Panels known to have a level of salts capable of beingeasily and quickly transported to the paint surface are used.Since tinted paints show the efflorescence most clearly, allwhite paints should be tinted before application. The panel isplaced face
10、down over the surface of the test chamber whichcontains heated water, so that moisture condenses and remainson the painted surface of the panel for a period of 48 h. Afterdrying at ambient conditions, the panels are rated for thedegree of efflorescence which has formed.5. Significance and Use5.1 Lat
11、ex paints are sometimes applied over substrates thatcontain a high level of water soluble salts that result inefflorescence. This practice evaluates a coatings vulnerabilityto efflorescence.6. Apparatus6.1 Condensation Test ChamberAs described in PracticeD 4585.6.2 Test SubstrateFiber-cement siding3
12、or a substrateagreed upon by the purchaser and seller. The substrate sizewould depend on the number of test paints.6.3 White Portland Cement and Graded Standard Sand (asdescribed in Practice D 1734).6.4 Trowel (as described in Practice D 1734).6.5 Paint BrushNylon/polyester brush of good quality.6.6
13、 Electronic Scale capable of 0.1 g.1This practice is under the jurisdiction of Committee D01 on Paint and RelatedCoatings, Materials, and Applications and is the direct responsibility of Subcom-mittee D01.42 on Architectural Coatings.Current edition approved on July 1, 2004. Published August 2004.2F
14、or 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.3Hardieplank, a registered trademark of James Hardie, was found
15、 to beacceptable but others may be used.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.7. Reagents and Materials7.1 Control Paint(s) (preferably tinted) The use of twocontrols (a pass and fail) may help gage the performance of thete
16、st paints.7.2 Test Paints (preferably tinted)Since there are nostandard panels, photographs, or paints for this test method, anagreed-upon control paint should be included as one of the testpaints.7.3 Using identical or similar tints for control(s) and testpaints may aid in relative evaluation of di
17、fferent formulations.7.4 If the goal is to evaluate alkali burnout, usually brightorganic colors will be more susceptible.8. Procedure8.1 Mix the cement : sand : water in the ratio as describedin Practice D 1734. Apply the mix approximately 6 mm (14 in.)thick over the fiber-cement siding using a tro
18、wel. Allow thepanels to dry for 24 h or as agreed upon by the purchaser andseller. Divide substrate into strips at least 150 mm (6 in.) wideor as agreed upon by the purchaser and the seller and label theback of each test area with the paint designation. The controlpaint should be placed near the mid
19、dle of the panel.8.2 Prepare paint brush as described in Practice D 5068.8.3 Using a brush, apply sufficient weight of test paints toachieve the desired spreading rate. If a second coat (top coat)is to be applied, allow the first coat to dry in the conditionedroom for 16 +/- 1 h (dry time may affect
20、 results) or as agreedupon by the purchaser and seller. Results may be highlydependent on film thickness; therefore, it is essential that thetest paints be weighed on accurately, particularly for small testareas. The amount of paint in grams required for a specificspread rate can be determined from
21、the following equation:g5A*W!/S!*3.15 (1)where:A = area, square inches,W = weight per gallon (Test Method D 1475), lb./gal, andS = Spreading rate, square ft/gal.Or the following metric equation:g5Am* D!/Sm! * 1000 (2)where:Am = area, square meters,D = density, g/mL or kg/L, andSm = spreading rate, s
22、quare meters/L.8.4 Allow the panels to dry at known conditions of tem-perature and relative humidity for 6 +/-1horasagreed uponby the purchaser and seller. Immediately place the panels onthe chamber with the painted sides facing toward the humidity.Close all cracks between boards to prevent water va
23、por lossand temperature variation. Larger cracks may be closed withtape or metal strips.8.5 Adjust the thermostat to maintain the desired tempera-ture of the saturated air and water vapor mixture. Cabinettemperature of 39C (100F) is suggested. To ensure adequatecondensation on the face of the panels
24、, maintain at least a 11C(20F) temperature differential between the room and theinside of the chamber.8.6 After 48 +/- 1 h, or an exposure time agreed upon by thepurchaser and seller, carefully remove the panels and allow todry overnight.9. Report9.1 Substrates used, test paints, control paint(s), t
25、opcoat,spreading rates, dry time of first coat, dry time of topcoat,vapor temperature and exposure time of topcoated panel forhumidity.9.2 Rate efflorescence of panels such as none, slight, mod-erate, or severe.9.3 Report any alkali burnout or any other film defects.10. Keywords10.1 alkali burnout;
26、efflorescenceASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of suc
27、h rights, are entirely their own responsibility.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 addit
28、ional standardsand should be addressed 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
29、 ASTM Committee on Standards, at the 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).D7072042
