ASTM-D2092

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Designation: D 2092 – 95 (Reapproved 2001)

Standard Guide for

Preparation of Zinc-Coated (Galvanized) Steel Surfaces for Painting1 This standard is issued under the fixed designation D 2092; the number immediately following the designation indicates the year of  original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript supers cript epsilon (e) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense. 1 e

NOTE—Footnote 3 was corrected editorially in June 2001.

1. Sco Scope pe

3.2.2   Method 3.2.3   Method 3.2.4   Method 3.2.5   Method 3.2.6   Method 3.2.7   Method Metho hod d 3.2.8   Met ment.

1.1 This gui guide de des descri cribes bes eig eight ht met method hodss of tre treati ating ng new zinc-coated (galvanized) surfaces produced by either the hotdip method or by electroplating. This practice covers surfaces that have not been treated previously at the mill to provide temporary protection against staining by moisture other than by easily removed protective oils (see   Appendix X1). X1). 1.2 The values values stated stated in SI units are to be reg regard arded ed as the standard. The values given in parentheses are for information only. standa ndard rd does not purport purport to add addre ress ss all of the 1.3   This sta safe sa fety ty co conc ncer erns ns,, if an anyy, as asso soci ciat ated ed wi with th it itss us use. e. It is th thee responsibility of the user of this standard to establish appro priate safety and health practices and determine the applicability of regulatory limitations prior to use.

B—Chromate Treatment. C —Aqueous —Aqueous Chromic-Organic Treatment. D—Acid-Curing Resinous Treatment. E —Annealing —Annealing Heat Treatments. F —Amorphous —Amorphous Complex-Oxide Treatment. G—Abrasive Blast Cleaning. H —Fluro-Ti —Fluro-Titanic/ tanic/Zircon Zirconic ic Polyme Polymerr Tre Treatat-

NOTE  1—Materials employed in these methods of treatment are available from a number of sources as proprietary compounds or methods. Selection may be made from available sources. NOTE 2—The use of solvents containing containing volatile organic compounds compounds to prepar pre paree or tre treat at the sur surfac facee of met metal al com compone ponents nts cont contrib ributes utes to air pollution in the same manner as the use of solvent containing paints and coatings. The user of this standard must determine the applicability of  appropriate approp riate regulations governing the volatile organic compound conten contentt of the materials used in a shop application (Miscellaneous Metal Parts), field painting (Archi (Architectura tectural), l), or specifi specificc proces processs industry industry..

2. Referenced Documents 2.1   ASTM Standards: D 1193   Specification for Reagent Water 2 2.2 Steel Structures Structures Painting Council Specification: Pain Pa intt No No.. 27   Basic Basic Zinc Chrom Chromateate-Vi Vinyl nyl Butyr Butyrol ol Wash Primer3

3.3 Variations in surface preparation preparation produce end conditions that differ, hence do not necessarily yield identical results when paints are subsequently applied. Service conditions will dictate the type of surface preparation preparation to be sele selected, cted, although although the qualit qua lity y pro produc duced ed by any ind indivi ividua duall met method hod ma may y var vary y wit with h different zinc coatings. 3.4 Galva Galvanize nized d surf surfaces aces are treated by using various various methods and apparatus; satisfactory application may be made at the following locations:

3. Summa Summary ry of Guide 3.1 This guide descr describes ibes treatment treatment meth methods ods that provide galvanized surfaces suitable for painting, specifically so that an applied coating system can develop the adhesion necessary for satisfactory service life. 3.2 Eight methods methods of surf surface ace preparation preparation (  (Note Note 1 and 1  and  Note 2) are covered as follows: 3.2.1   Method A—Zinc Phosphate Treatment.

Method A Method B Method C Method D Method E Method F Method G Method H

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This guide is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Coatings, Materials, and Appli Applications cations and is the direct respon responsibility sibility of  Subcommittee D01.46 on Industrial Protective Coatings. Current Cur rent edi editio tion n app approv roved ed Apr April il 15, 199 1995. 5. Pub Publish lished ed Jun Junee 199 1995. 5. Ori Origin ginally ally published publis hed as D 2092 – 86. Last previo previous us edition D 2092 – 86 (1993). (1993). 2  ASTM Book of Standards Standards,, Vol 11.01. 3 Available from The Society For Protective Coatings (SSPC), 2100 Wharton St., Suite 310, Pittsburgh, PA 15203–1951.

Mill Y Y Y Y Y Y Y Y

Plant Y Y Y Y ... Y Y Y

Field Y ... ... Y ... ... Y ...

3.5 This guide does not describe the cleaning cleaning necessary necessary to provide prov ide a zinc zinc-coat -coated ed (gal (galvaniz vanized) ed) surfa surface ce suita suitable ble for the applic app licati ation on of the tre treatm atment ents. s. Man Many y cle cleani aning ng met method hodss are applicable and should be agreed upon between the purchaser and the supplier.

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.

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D 2092 2092 – 95 95 (20 (2001) 01) NOTE  3—Most producers of zinc-coated (galvanized) steel sheets and coils have adopted the practice of applying an inhibitor to the zinc surface to give tempor temporary ary protection against staining by moisture during shipping or storage. Some of these inhibitors inhibitors interfere with proper reaction of most of the treatments described in these methods, and an unsatisfactory surface for painting results. It is strongly recommended that the purchaser consult the supplier of the chemic chemical al treatment to be used as to the suitability of the zinc surfaces for treatment by any of these methods (see Appendix (see Appendix X2). X2).

not be softened by organic solvents commonly used in paint coatings. The film has good adhesion to the metal substrate and promotes good adhesion of most subsequent organic coatings to it itse self lf.. Two ty type pess of th this is tr trea eatm tmen entt ar aree av avai aila labl ble: e: ( 1) two-package material to be used the day it is mixed and ( 2) one-package material that has package stability and does not require daily preparation.

4. Signi Significanc ficancee and Use

NOTE 4—It may be difficult difficult to control the dry film thickness within the parameter parame terss of this specificat specification ion whe when n appl applied ied by bru brush, sh, rol roller ler,, or dip coater.

4.1 Thi Thiss gui guide de des descri cribes bes pro proced cedure uress tha thatt can be use used d to prepare new zinc-coated surfaces for painting and improve the bond of paint to the zinc surface.

5.5  Method E, Annealing Heat Treatments —Under the controlle tro lled d con condit dition ionss obt obtain ainabl ablee in a mil mill, l, hot hot-di -dip p gal galvan vanize ized d surfaces may be converted and alloyed with the base metal to change the surface character of the zinc coating and make it more receptive to paint. This surface can be further improved by treating in accordance with Methods A, B, C, or D. 5.6  Method F, Amorphous Complex-Oxide Treatment —This —This surface treatment method consists of reacting the zinc surface in an alkaline solution containing heavy metal ions for a period of 5 to 30 s at 45 to 70°C (115 to 160°F). The surface of the zinc is converted to a nonmetallic, amorphous, complex-oxide coating that inhibits corrosion and increases the adhesion and durability of paint finishes. The treatment can be carried out by immersion or spray application. Abrasive ive Blast Treatmen Treatment  t —This 5.7   Method G, Abras —This treatment method consists of mechanical etching or deformation of the galvanized surface using abrasive propelled with compressed air or water. Because of the soft nature of the galvanized metal zinc layer, it is critical that soft abrasives or reduced operating pressures pres sures,, or both both,, be empl employed. oyed. Excessive Excessive oper operating ating pressures, high hardness abrasives, and long dwell times can result in removal of zinc coating thickness (see  Appendix X3). X3). 5.8  Method H, Fluro-Titanic/Zirconic Polymer Treatment — This Th is tr trea eatm tmen entt me meth thod od is a ch chro romi mium um fr free ee an anal alog og of th thee solutions commonly employed under Method C. It consists of  a combination of poly(acrylic acid) with copolymer resins and 0.01 to 0.1 M H2TiF6 or H2ZrF6. The solution can be applied to the galvanized steel surface by spray, dip, squeegee or roller coating. The excess solution is spun-off or otherwise removed from fro m the met metal al sur surfac face, e, res result ulting ing in a dry inin-pla place ce sur surfac facee treatment. The finished surface consists of a complex oxide polymer matrix bound to the zinc metal.

5. Proc Processe essess 5.1 Me th — th od od A , Z in in c P ho ho sp sp ha ha te te Tre at at me me nt nt —This   This conversion-coating method consists of reacting the zinc surface in a zinc acid phosphate solution containing oxidizing agents and other salts for accelerating the coating action. The zinc surface is converted to a crystalline phosphate coating of the proper texture to inhibit corrosion and increase the adherence and durability of the paint film. Such treatments are recommend me nded ed fo forr pr prod oduc uctt fin finis ishe hess an and d ma may y be ca carr rrie ied d ou outt by immersion, spray, or brush application. Chromate omate Trea reatment  tment —This 5.2   Method B, Chr —This trea treatmen tmentt consists of a dip or spray with a dilute solution of a mixture of  chromium trioxide and other acids, with the proper accelerator, forr a pe fo peri riod od fr from om 5 to 30 s at ro room om te temp mper erat atur uree to 55°C (130°F) (130° F) to provi provide de a thin amorphous amorphous chrom chromate ate coating that increases corrosion resistance and paint adhesion. Method C, Aqueo Aqueous us Chr Chromicomic-Org Organic anic Tr Treatme eatments nts— 5.3   Method Certain Certa in water water-sol -soluble uble resi resins, ns, when prope properly rly form formulat ulated ed with chromi chr omium um com compou pounds nds,, may be app applie lied d to zin zincc sur surfac faces es by roller coat or other suitable means, such as dip and squeegee roll ro lls. s. Th This is ma may y be do done ne ov over er a wi wide de te temp mper erat atur uree ra rang ngee prov pr ovid ided ed th thee fil film m is pr prop oper erly ly ba bake ked d or cu cure red, d, or bo both th,, as requir req uired ed by the pai paint nt sys system tem to be app applie lied. d. The res result ultant ant coating coati ng prov provides ides a corr corrosion osion-res -resista istant nt film that increases increases the adhesion of applied paint films. Treatment eatment (Vinyl Wash Wash 5.4 Method D, Acid-Curing Resinous Tr Primer) (See SSPC-Paint No. 27) —This surface treatment is based bas ed on the app applic licati ation on of an aci acid-c d-curi uring ng res resino inous us film of  approx app roxim imate ately ly 8 to 1313-µm µm (0. (0.3 3 to 0.5 0.5-mi -mil) l) thi thickn ckness ess.. The treatment is based on three primary components: a hydroxylcontaining resin, a pigment capable of reacting with the resin and an acid, and an acid capable of insolubilizing the resin by reacting with the resin, the pigment, and the zinc surface. The film is usually applied by spray, but may be applied by brush, dip,, or rol dip roller ler coa coater ter.. Und Under er nor normal mal con condit dition ionss it wil willl dry sufficiently for recoating within 30 min, and within 8 h it will

6. Keyw Keywords ords 6.1 acid-curing acid-curing resi resinous nous trea treatmen tment; t; amor amorphous phous compl complexexoxide treatment; annealing heat treatment; chromate; chromate test;; chrom test chromic-o ic-organ rganic ic treat treatment ment;; galva galvanize nize;; phosp phosphate hate;; pretreatment; surface treatment; zinc

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D 2092 2092 – 95 95 (20 (2001) 01) APPENDIXES (Nonmandatory Information)

X1. CLEAN CLEANING ING OF ZINC SURF SURFACES ACES

X1.1 When zinc zinc surfaces surfaces have been soiled soiled in fabrication, fabrication, they sho they should uld be cle cleane aned d bef before ore fini finishi shing. ng. Alkali Alkali and aci acid d cleaners should not be used without consulting the supplier of  the treatment. Organic solvents remove most soils, but do not remove remo ve water water-sol -soluble uble salt saltss unle unless ss speci specially ally sele selected. cted. Propr Propriietary solutions designed to clean zinc surfaces are available.

air pollution in the same manner as the use of solvent containing paints and coatings. The user of this guide must determine the applicability of  appropriate approp riate regulations governing the volatile organic compound conten contentt of generic or propri proprietary etary materials used to clean zinc-coated zinc-coated surfaces, either in shop applications (Miscellaneous (Miscellaneous Metal Parts) Parts),, field painting (Architectural), or specific process industry.

NOTE   X1.1—Th X1.1—Thee use of solv solvent entss con contain taining ing vola volatile tile org organi anicc com com-pounds to prepare or clean the surface of metal components contributes to

X2. IDENTIFYING THE PRESENCE OF AND REMOVING CHROMATE TREATMENTS TREATMENTS USED AS WET-STORAGE WET-STORAGE (ALSO CALLED HUMID-STORAGE) STAIN INHIBITORS

X2.1 One of the inhibitors used used by producers producers of zinc-coated zinc-coated steel is a hexavalent chromium solution. This treatment prevents Method D from working properly.

X2.5.2 Dilut Dilutee 20 mL of concentrated concentrated phosphori phosphoricc acid to 40 mL by slowly adding to 20 mL of reagent water conforming to Type IV of Specification  D 1193. 1193. X2.5. X2 .5.3 3 Ad Add d th thee di dilu lute te ph phos osph phor oric ic ac acid id to th thee ac acet eton oneealcohol solution. X2.5.4 X2. 5.4 Store the solution solution away fro from m lig light. ht. Dis Discar card d if it becomes discolored. Preferably make fresh solution as needed using proportionally smaller amounts of ingredients.

X2.2 X2. 2 If zinc-co zinc-coate ated d ste steel el to be painted painted is galvaniz galvanized ed to order, the order should prohibit the use of hexavalent chromium humid-storage stain treatments. X2.3 Hexavalent chromium chromium treatment can be removed from galvanized surfaces by one of the following three methods:

X2.6 Condu Conduct ct the spot spot test test as follows: follows:

X2.3.1 Weath eathering ering the surfaces surfaces for six mont months. hs. X2.3.2 Abrad Abrading ing the surfaces by sanding. X2.3.3 Brush-of Brush-offf abrasive blast cleaning.

X2.6.1 Degre Degrease ase the test spot on the galv galvanize anized d surface. X2.6. X2 .6.2 2 Place Place se seve vera rall dr drop opss of th thee te test st so solu luti tion on on th thee galvanized surface. X2.6.3 X2. 6.3 If no col color or develops develops in the solutio solution n wit within hin 10 s, hexavalent chromium is not present. X2.6.4 If solution solution droplets turn a pink to purp purple le color, color, then hexavalent chromium is present. X2.6.5 Conduct the spot test on several representative representative spots spots on each individual piece of galvanized steel. X2.6.6 Test   every   piece piece of gal galvan vanize ized d ste steel el tha thatt is to be treated for painting.

X2.4 The presence presence of hexavalent hexavalent chromium chromium on galvanized galvanized surfaces can be determined by spot testing with diphenylcarbohydrazide solution. The spot test can also be used to evaluate the effectiveness of preparation to remove the treatment. X2.5 Make the spot spot test test solution solution as follows: follows: X2.5.1 Disso Dissolve lve 0.5 g of 1,5-diphenylca 1,5-diphenylcarbohy rbohydraz drazide ide powder in a mi der mixt xtur uree of 20 mL aceto acetone ne an and d 20 mL denat denatur ured ed ethanol. Heat the mixture in a warm water bath if necessary.

X3. ABRAS ABRASIVE IVE BLASTING BLASTING

X3.1 Typica ypicall abrasives abrasives might include include soft mineral mineral sands with a mohs hardness #5, or organic media, such as corn cobs or walnut shells.

X3.2 Typi X3.2 ypical cal operati operating ng pre pressu ssures res might might be measured at the blasting nozzle.

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60 ps psig ig

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D 2092 2092 – 95 95 (20 (2001) 01)

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