ASTM_D_1641_-_97.pdf

Designation:D 1641 97Standard Practice forConducting Outdoor Exposure Tests of Varnishes1This standard is issued under the fixed designation D 1641;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 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 procedure for evaluating dura-bility of varnishes applied to a wooden substrate.1.2 The values stated in inch-pound units are to be regardedas the standard.The values given in parentheses are forinformation only.1.3 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.Referenced Documents2.1 ASTM Standards:D 962 Specification for Aluminum Powder and Paste Pig-ments for Paints2D 3924 Specification for Standard Environment for Condi-tioning and Testing Paint,Varnish,Lacquers,and RelatedMaterials32.2U.S.Federal Specification:TT-V-11943.Apparatus and Materials3.1 Maple Panels,of close-grained clear maple,3 by 12 by12in.(75 by 305 by 13 mm),with all edges rounded to a14-in.(6.4-mm)radius.3.2 Varnish Brushes,1-in.(25-mm)pure bristle.3.3 Sandpaper,180-grit.3.4 Balance,capable of weighing to an accuracy of 0.1 g.3.5 Tung-Linseed Phenolic Aluminum Sealer,composed ofa varnish complying with the nonvolatile vehicle compositionrequirements of U.S.Federal Specification TT-V-1195;(Julyl973)that is,approximately 65%oil content with a minimumof 45%tung oil,and linseed and castor oils as required,andaluminum paste meeting the requirements of SpecificationD 962,Type II,Class B,using 1 gal of vehicle and 2 lb of paste(288 g paste to 1 L of varnish).If varnish to TT-V-119 is notavailable,another agreed upon material of known performancemay be used.4.Preparation of Test Panels4.1 Weight of PanelWeigh the test panel to the nearest 0.1g,prior to varnishing.4.2 Application of First CoatFor the first application ofthe varnish under test coat both faces,ends,and edges of eachpanel,using a small brush and taking the precaution to brushthe coat out well.Allow the varnish to dry 24 h at roomtemperature(as defined in Specification D 3924)before apply-ing the second coat.4.3 Application of Second CoatBefore applying the sec-ond coat,lightly sand the panel with 180-grit sandpaper,takingcare not to touch the faces of the panel after sanding,andremove sanding dust by air-blowing or vacuuming.Reweighthe panel and record the final weight of the first coat.Thenapply a second coat of the varnish as evenly as possible,covering both faces and all edges of the panel.Apply thesecond coat as evenly as possible.Allow to dry for 24 h beforeapplying the third coat.4.4 Application of Third CoatSand,clean and reweigh thepanel as in 4.3.Apply the third coat,covering both faces andedges,with a full brush,laying the varnish on as evenly aspossible.Weigh the panel and record the weight of the thirdcoat.4.5Application of Aluminum SealerPrepare the varnishbased aluminum sealer as directed in 3.5.Coat one face and allthe edges of the panel with a smooth even coat.Take great careto ensure that the ends are completely covered.Allow thecoated panel to dry a minimum of 24 h before exposure.5.Procedure5.1 Unless otherwise agreed upon or specified,expose allpanels in a test series with appropriate positive and negativecontrols(see Note 1)facing the equator at 45 or other agreedupon angle at a time appropriate for the latitude of the site.Theweather conditions at the site should,if possible,be similar toconditions where the varnish is regularly used.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.42 on Architectural Finishes.Current edition approved Nov.10,1997.Published August 1998.Last previousedition D 1641 96.2Annual Book of ASTM Standards,Vol 06.03.3Annual Book of ASTM Standards,Vol 06.01.4Available from Standardization Documents Order Desk,Bldg.4 Section D,700Robbins Ave.,Philadelphia,PA 19111-5094,Attn:NPODS.5The oil content was increased on the basis of studies reported in the Journal ofPaint Technology,Vol 39,Issue 507,April 1967,p.212.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.NOTE1The varnish described in 3.5 is considered to be a positivecontrol while a clear alkyd or oil modified urethane is suitable for anegative control.5.2 Inspect the panels at half-yearly intervals,adjusting thistime according to the rapidity or slowness of degradation of thecoatings.Examine each panel for the following failure charac-teristics,rating each type of failure on the 0 to 10 scale where10 is