ASTM D1730-09(2014)
(Practice)Standard Practices for Preparation of Aluminum and Aluminum-Alloy Surfaces for Painting
Standard Practices for Preparation of Aluminum and Aluminum-Alloy Surfaces for Painting
ABSTRACT
These practices cover the different procedures employed in performing four types of treatments for the preparation of aluminum and aluminum alloy surfaces for painting. These processes are broadly classified into the following treatment types: solvent cleaning (Type A); chemical treatments (Type B); anodic treatments (Type C); and mechanical treatments (Type D). Service conditions shall dictate the type of surface preparation that should be employed, although the quality produced by any individual method may still vary with the type of alloy involved. Solvent cleaning does not disturb the natural oxide film on the metal and is applicable in ambient indoor or very mild service conditions. This treatment type may be performed by three methods, as follows: manual swabbing or dip washing; solvent spray cleaning; or vapor degreasing. Chemical treatments may be employed by the following eight methods: alkaline cleaners; sulfuric acid, chromium trioxide etch; alcoholic phosphoric acid cleaner; crystalline phosphate treatment; amorphous phosphate treatment; carbonate chromate treatment; amorphous chromate treatment; or 8) acid-bound resinous treatment. Anodic treatments will provide a protective inert oxide coating which increases corrosion resistance and promotes paint adhesion. This is recommended where maximum corrosion resistance by the treatment itself is desired, but should not be used on assemblies of dissimilar metals. This treatment type may be executed by two methods, namely: sulfuric acid anodic, or chromium trioxide anodic treatment. Mechanical treatments may be implemented by these two methods: hand or power wire brushing or other abrasive treatment; or sandblasting.
SCOPE
1.1 These practices cover four types of treatment for preparation of aluminum and aluminum-alloy surfaces for painting, as follows:
1.1.1 Type A—Solvent Cleaning.
1.1.2 Type B—Chemical Treatments.
1.1.3 Type C—Anodic Treatments.
1.1.4 Type D—Mechanical Treatments. These four types cover a number of procedures, as described herein.
1.2 Variations in surface treatment produce end conditions which differ, and which do not necessarily yield identical results when paints are applied. Service conditions will dictate the type of surface preparation that should be selected, although the quality produced by any individual method may vary with different alloys.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D1730 − 09 (Reapproved 2014)
Standard Practices for
Preparation of Aluminum and Aluminum-Alloy Surfaces for
Painting
This standard is issued under the fixed designation D1730; 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 epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope MIL-DTL-5541 Chemical Conversion Coatings on Alumi-
num and Aluminum Alloys
1.1 These practices cover four types of treatment for prepa-
MIL-M-10578B Metal Conditioner and Rust Remover
ration of aluminum and aluminum-alloy surfaces for painting,
(Phosphoric Acid Type)
as follows:
MIL-P-15328bB Coating Compound – Metal Pretreatment
1.1.1 Type A—Solvent Cleaning.
Resin Resistant
1.1.2 Type B—Chemical Treatments.
1.1.3 Type C—Anodic Treatments.
2.3 Federal Specification:
1.1.4 Type D—Mechanical Treatments. These four types
TT-C-490 Chemical Conversion Coatings and Pretreatments
cover a number of procedures, as described herein.
for Ferrous Surfaces (Base for Organic Coatings)
1.2 Variations in surface treatment produce end conditions
3. Type A—Solvent Cleaning
which differ, and which do not necessarily yield identical
results when paints are applied. Service conditions will dictate
3.1 Solvent cleaning does not disturb the natural oxide film
the type of surface preparation that should be selected, al-
on the metal and may prove adequate for some applications,
though the quality produced by any individual method may
such as ambient indoor or very mild service conditions. Three
vary with different alloys.
methods may be employed, as follows:
1.3 This standard may involve hazardous materials,
3.1.1 Method 1, Manual Swabbing or Dip-Washing, with a
operations, and equipment. This standard does not purport to
solvent such as mineral spirits or high-flask solvent naphtha.
address all of the safety concerns, if any, associated with its
With this method it is extremely difficult to prevent accumu-
use. It is the responsibility of the user of this standard to
lation of contaminants on the swab or in the solvent. This
establish appropriate safety and health practices and deter-
method is only recommended when other treatments are
mine the applicability of regulatory limitations prior to use.
impractical.
3.1.2 Method 2, Solvent Spray Cleaning , in accordance
2. Referenced Documents
with Method A, Procedure 1 of Practice D609.
2.1 ASTM Standards:
3.1.3 Method 3, Vapor Degreasing , in special equipment
D609 Practice for Preparation of Cold-Rolled Steel Panels
employing trichloroethylene vapor, in accordance with Method
for Testing Paint, Varnish, Conversion Coatings, and
A, Procedure 2 of Practice D609.
Related Coating Products
2.2 Military Standards:
4. Type B—Chemical Treatments
MIL-A-8625 AnodicCoatingsforAluminumandAluminum
NOTE 1—Materials and procedures employed in these methods of
Alloys
treatment are available from a number of sources as proprietary com-
pounds or methods. Selection may be made from available sources. The
ThesepracticesareunderthejurisdictionofASTMCommitteeB08onMetallic
hexavalent chromium methods given are not recommended as hexavalent
and Inorganic Coatings and is the direct responsibility of B08.07Conversion
chromium is a known carcinogen.
Coatings on Chromate Conversion Coatings.
Current edition approved Nov. 1, 2014. Published November 2014. Originally
4.1 Method 1, Alkaline Cleaners—Alkaline solutions, such
approved in 1960. Last previous edition approved in 2009 as D1730-09. DOI:
as caustic soda, etch the metal, thus destroying the natural
10.1520/D1730-09R14.
oxide film. They are followed by an acid treatment, preferably
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
nitric acid or phosphoric acid. They shall not be used on
Standards volume information, refer to the standard’s Document Summary page on
assembledstructures.Inhibitedalkalinecleanersaresometimes
the ASTM website.
3 employedasapretreatmenttoremovegreaseandoilpriortoan
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098 acid treatment. Inhibited alkaline cleaners do not etch the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1730 − 09 (2014)
surface. They are not generally recommended unless followed application.The time of treatment will vary from 15 to 45 s for
by a conversion treatment, such as described in Methods 4, 5, the spray process, and from 30 s to 3 min for the immersion
6, or 7. application (see Note 3 and Note 5).
NOTE 5—Most of the treatments conforming to Methods 5, 6, and 7 of
4.2 Method 2, Sulfuric Acid, Chromium Trioxide Etch
Type B comply with the requirements of U. S. Military Specification
—This treatment provides a clean and uniform surface without
MIL-DTL-5541.
undue etching, and is effective for removing oil and water
4.6 Method 6, Carbonate Chromate Treatment—This pro-
stains and any film formed during heat-treatment. The etching
cess comprises treatment in a hot (180 to 190°F (82 to 88°C))
solution is prepared by adding 1 gal (3.78 L) of concentrated
dilute solution of sodium carbonate and potassium chromate
sulfuric acid and 45 oz (1.28 kg) of chromium trioxide to 9 gal
for periods from 2 to 20 min, followed by a water rinse. The
(34 L) of water. It is used at a temperature of 160 to 180°F (71
surface is then given a final treatment in hot 5% potassium
to 82°C) (depending on the alloy and the amount of film) for
dichromate solution, followed by a final rinse. The treatment
about 5 min and is followed by a water rinse. This treatment
produces a thin, adherent, conversion coating on the surface,
produces a passive surface suitable for painting under mild to
increasing the corrosion resistance of the metal and promoting
intermediate exposure conditions and where clear finishes are
paint adhesion. This method is recommended for use under the
to be applied.
more severe conditions of service and for product finishes (see
4.3 Method 3, Alcoholic Phosphoric Acid Cleaner—This
Note 3 and Note 5).
treatment involves the use of an aqueous solution of phos-
4.7 Method 7, Amorphous Chromate Treatment—This pro-
phoric acid (10 to 15 volume %) with alcohol or other organic
cess comprises treatment of clean aluminum surfaces in
solvents, together with wetting agents, emulsifying agents, etc.
aqueous chromium trioxide solutions containing suitable ac-
The solution may be applied by swabbing or dipping at room
celerating agents such as fluoride-containing materials. The
temperature (70 to 90°F (21 to 32°C)), and should be allowed
aluminum surface is converted to an adherent, amorphous,
to remain on the surface for several minutes, followed by
mixedmetallicoxidecoating,irridescentgoldentolight-brown
thorough rinsing with clean water. A very thin phosphate film
in color, which increases the corrosion-resistance and the
is formed which tends to protect the metal and promote paint
adherence an
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D1730 − 09 D1730 − 09 (Reapproved 2014)
Standard Practices for
Preparation of Aluminum and Aluminum-Alloy Surfaces for
Painting
This standard is issued under the fixed designation D1730; 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 epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 These practices cover four types of treatment for preparation of aluminum and aluminum-alloy surfaces for painting, as
follows:
1.1.1 Type A—Solvent Cleaning.
1.1.2 Type B—Chemical Treatments.
1.1.3 Type C—Anodic Treatments.
1.1.4 Type D—Mechanical Treatments. These four types cover a number of procedures, as described herein.
1.2 Variations in surface treatment produce end conditions which differ, and which do not necessarily yield identical results
when paints are applied. Service conditions will dictate the type of surface preparation that should be selected, although the quality
produced by any individual method may vary with different alloys.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all
of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate
safety and health practices and determine the applicability of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
D609 Practice for Preparation of Cold-Rolled Steel Panels for Testing Paint, Varnish, Conversion Coatings, and Related Coating
Products
2.2 Military Standards:
MIL-A-8625 Anodic Coatings for Aluminum and Aluminum Alloys
MIL-DTL-5541 Chemical Conversion Coatings on Aluminum and Aluminum Alloys
MIL-M-10578B Metal Conditioner and Rust Remover (Phosphoric Acid Type)
MIL-P-15328bB Coating Compound – Metal Pretreatment Resin Resistant
2.3 Federal Specification:
TT-C-490 Chemical Conversion Coatings and Pretreatments for Ferrous Surfaces (Base for Organic Coatings)
3. Type A—Solvent Cleaning
3.1 Solvent cleaning does not disturb the natural oxide film on the metal and may prove adequate for some applications, such
as ambient indoor or very mild service conditions. Three methods may be employed, as follows:
3.1.1 Method 1, Manual Swabbing or Dip-Washing, with a solvent such as mineral spirits or high-flask solvent naphtha. With
this method it is extremely difficult to prevent accumulation of contaminants on the swab or in the solvent. This method is only
recommended when other treatments are impractical.
3.1.2 Method 2, Solvent Spray Cleaning , in accordance with Method A, Procedure 1 of Practice D609.
These practices are under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of B08.07Conversion Coatings
on Chromate Conversion Coatings.
Current edition approved April 15, 2009Nov. 1, 2014. Published May 2009November 2014. Originally approved in 1960. Last previous edition approved in 20032009
as D1730-03.-09. DOI: 10.1520/D1730-09.10.1520/D1730-09R14.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1730 − 09 (2014)
3.1.3 Method 3, Vapor Degreasing , in special equipment employing trichloroethylene vapor, in accordance with Method A,
Procedure 2 of Practice D609.
4. Type B—Chemical Treatments
NOTE 1—Materials and procedures 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. The hexavalent chromium methods given are not recommended as hexavalent chromium is a
known carcinogen.
4.1 Method 1, Alkaline Cleaners—Alkaline solutions, such as caustic soda, etch the metal, thus destroying the natural oxide
film. They are followed by an acid treatment, preferably nitric acid or phosphoric acid. They shall not be used on assembled
structures. Inhibited alkaline cleaners are sometimes employed as a pretreatment to remove grease and oil prior to an acid
treatment. Inhibited alkaline cleaners do not etch the surface. They are not generally recommended unless followed by a conversion
treatment, such as described in Methods 4, 5, 6, or 7.
4.2 Method 2, Sulfuric Acid, Chromium Trioxide Etch —This treatment provides a clean and uniform surface without undue
etching, and is effective for removing oil and water stains and any film formed during heat-treatment. The etching solution is
prepared by adding 1 gal (3.78 L) of concentrated sulfuric acid and 45 oz (1.28 kg) of chromium trioxide to 9 gal (34 L) of water.
It is used at a temperature of 160 to 180°F (71 to 82°C) (depending on the alloy and the amount of film) for about 5 min and is
followed by a water rinse. This treatment produces a passive surface suitable for painting under mild to intermediate exposure
conditions and where clear finishes are to be applied.
4.3 Method 3, Alcoholic Phosphoric Acid Cleaner—This treatment involves the use of an aqueous solution of phosphoric acid
(10 to 15 volume %) with alcohol or other organic solvents, together with wetting agents, emulsifying agents, etc. The solution
may be applied by swabbing or dipping at room temperature (70 to 90°F (21 to 32°C)), and should be allowed to remain on the
surface for several minutes, followed by thorough rinsing with clean water. A very thin phosphate film is formed which tends to
protect the metal and promote paint adhesion under mild to intermediate exposure conditions.
NOTE 2—U.S. Military Specification MIL-M-10578B describes a treatment of this type.
4.4 Method 4, Crystalline Phosphate Treatment—This surface-coating method consists in reacting the aluminum surface in a
zinc-acid-phosphate solution containing oxidizing agents and other salts for accelerating the coating action. The aluminum surface
is converted to a finely crystalline, phosphate coating of the proper texture adapted to inhibit corrosion and increase the adherence
and durability of any applied paint film. It is recommended for product finishes. The phosphate coating process may be carried out
by immersion or spray application. The aluminum surface is converted to the phosphate coating by immersion in the processing
solution for 30 s to 4 min at 125 to 140°F (51 to 60°C), or by spraying the solution for 10 s to 2 min at 125 to 160°F (51 to 71°C).
NOTE 3—Before applying the treatments according to Methods 4, 5, 6, and 7 of Type B, the aluminum surfaces should be freed of grease, oil, or other
foreign material by means of the procedure described in Method 3 of Type A, Method 1 of Type B, or any other suitable method.
NOTE 4—This
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