ASTM_D_4147_-_99_2013.pdf

Designation:D414799(Reapproved 2013)Standard Practice forApplying Coil Coatings Using The Wire-Wound DrawdownBar1This standard is issued under the fixed designation D4147;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()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers a procedure for applying a coatingfilm of uniform thickness on a flat panel using the wire-wounddrawdown bar.1.2 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.Summary of Practice2.1 A flat panel is secured on a firm horizontal surface.Anample amount of coating is poured across one end of the paneland the drawdown bar placed behind the coating.The bar isthen drawn with uniform pressure and speed along the lengthof the panel toward the operator to apply a uniform film.Thewet and dry film coating thickness obtained is dependent on thecombination of the bar used,the volume solids of the coating,and the speed of the drawdown motion.3.Significance and Use3.1 This practice is useful in the laboratory to simulateroll-coated films.4.Apparatus4.1 Wire-Wound Drawdown BarsA set of stainless steelwire-wound drawdown bars of sufficient diameter to preventbowing during application.These bars are manufactured sothat the diameter of the wire wound on the bar controlsthickness of the wet film applied.The choice of specificdrawdown bar is dependent on the dry film thickness requiredand the volume solids of the coating under test.4.2 Devices for Securing Panels:4.2.1 Magnetic Chuck for securing steel panels to eliminatebowing.4.2.2 Vacuum Plate for securing very lightweight nonmag-netic panels.4.2.3 Tape for securing the top of thin-gage panels.4.2.4 Mechanical Drives,for securing panels and automat-ing the drawdown procedure.5.Hazards5.1 The flash points of most solvents used in coatings andrelated products are low enough that adequate ventilation isneeded to avoid exceeding 25%of the lower explosive limitsof the solvent when preparing and baking the panels.Thesesolvents could be toxic,care should be taken to avoid inhala-tion of the vapors and unnecessary contact of the solvents withthe skin.6.Procedure6.1 Deburr panels so edges are smooth.Secure a flat panelto be coated on a firm,uniform,level surface.To providesufficient testing surface pour an ample amount of coatingacross the end of the panel.Place the drawdown bar behind thecoating and pull into the coating.Rotate the drawdown bar inthe coating to ensure complete wetting of the coating in thethreads of the bar.Apply uniform pressure across the contactlength of the drawdown bar and hold it firmly without allowingrotation.Using only one pass,draw the bar along the length ofand off the panel at a uniform speed so that a continuous filmis produced.Application of the coating is dependent upon therheology,type of coating,and speed and pressure to achievethe uniform desired film.Remove the coated panel and bake,force dry,or air dry the coating in accordance with its type soits dry film thickness can be measured.Aheavier film thicknessis obtained along the edges of the panel and possibly at the topof the panel where the coating was poured.For a two-coatsystem,the side edges must be trimmed to eliminate theheavier areas on the first coat before applying the second coat.7.Keywords7.1 coil coatings;drawdown bars1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.53 on Coil Coated Metal.Current edition approved June 1,2013.Published June 2013.Originallyapproved in 1982.Last previous edition approved in 2007 as D4147 99(2007)1.DOI:10.1520/D4147-99R13.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 ASTM 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 such 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 additional 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