ASTM D1730-09(2020)
(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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D1730 − 09 (Reapproved 2020)
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 D609 Practice for Preparation of Cold-Rolled Steel Panels
for Testing Paint, Varnish, Conversion Coatings, and
1.1 These practices cover four types of treatment for prepa-
Related Coating Products
ration of aluminum and aluminum-alloy surfaces for painting,
2.2 Military Standards:
as follows:
MIL-A-8625 AnodicCoatingsforAluminumandAluminum
1.1.1 Type A—Solvent Cleaning.
Alloys
1.1.2 Type B—Chemical Treatments.
MIL-DTL-5541 Chemical Conversion Coatings on Alumi-
1.1.3 Type C—Anodic Treatments.
num and Aluminum Alloys
1.1.4 Type D—Mechanical Treatments. These four types
MIL-M-10578B Metal Conditioner and Rust Remover
cover a number of procedures, as described herein.
(Phosphoric Acid Type)
1.2 Variations in surface treatment produce end conditions
MIL-P-15328bB Coating Compound – Metal Pretreatment
which differ, and which do not necessarily yield identical
Resin Resistant
results when paints are applied. Service conditions will dictate
2.3 Federal Specification:
the type of surface preparation that should be selected, al-
TT-C-490 Chemical Conversion Coatings and Pretreatments
though the quality produced by any individual method may
for Ferrous Surfaces (Base for Organic Coatings)
vary with different alloys.
1.3 This standard may involve hazardous materials, 3. Type A—Solvent Cleaning
operations, and equipment. This standard does not purport to
3.1 Solvent cleaning does not disturb the natural oxide film
address all of the safety concerns, if any, associated with its
on the metal and may prove adequate for some applications,
use. It is the responsibility of the user of this standard to
such as ambient indoor or very mild service conditions. Three
establish appropriate safety, health, and environmental prac-
methods may be employed, as follows:
tices and determine the applicability of regulatory limitations
3.1.1 Method 1, Manual Swabbing or Dip-Washing, with a
prior to use.
solvent such as mineral spirits or high-flask solvent naphtha.
1.4 This international standard was developed in accor-
With this method it is extremely difficult to prevent accumu-
dance with internationally recognized principles on standard-
lation of contaminants on the swab or in the solvent. This
ization established in the Decision on Principles for the
method is only recommended when other treatments are
Development of International Standards, Guides and Recom-
impractical.
mendations issued by the World Trade Organization Technical
3.1.2 Method 2, Solvent Spray Cleaning, in accordance with
Barriers to Trade (TBT) Committee.
Method A, Procedure 1 of Practice D609.
3.1.3 Method 3, Vapor Degreasing, in special equipment
2. Referenced Documents
employing trichloroethylene vapor, in accordance with Method
2.1 ASTM Standards:
A, Procedure 2 of Practice D609.
4. Type B—Chemical Treatments
ThesepracticesareunderthejurisdictionofASTMCommitteeB08onMetallic
NOTE 1—Materials and procedures employed in these methods of
and Inorganic Coatings and are the direct responsibility of Subcommittee B08.07 on
treatment are available from a number of sources as proprietary com-
Conversion Coatings.
pounds or methods. Selection may be made from available sources. The
Current edition approved May 1, 2020. Published May 2020. Originally
hexavalent chromium methods given are not recommended as hexavalent
approved in 1960. Last previous edition approved in 2014 as D1730 – 09(2014).
chromium is a known carcinogen.
DOI: 10.1520/D1730-09R20.
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 Available from Standardization Documents Order Desk, DODSSP, Bldg. 4,
the ASTM website. 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 (2020)
4.1 Method 1, Alkaline Cleaners—Alkaline solutions, such solution thereof. The aluminum surface is converted to a thin,
as caustic soda, etch the metal, thus destroying the natural adherent, amorphous coating, iridescent green to gray-green in
oxide film. They are followed by an acid treatment, preferably
color, depending upon the aluminum alloy treated, which
nitric acid or phosphoric acid. They shall not be used on
inhibitscorrosionandincreasestheadherenceanddurabilityof
assembledstructures.Inhibitedalkalinecleanersaresometimes
applied paint films.This method is recommended for use under
employedasapretreatmenttoremovegreaseandoilpriortoan
the more severe conditions of service, and for product finishes.
acid treatment. Inhibited alkaline cleaners do not etch the
The coating process may be carried out by immersion or spray
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).
4.2 Method 2, Sulfuric Acid, Chromium Trioxide Etch
NOTE 5—Most of the treatments conforming to Methods 5, 6, and 7 of
—This treatment provides a clean and uniform surface without
Type B comply with the requirements of U. S. Military Specification
undue etching, and is effective for removing oil and water
MIL-DTL-5541.
stains and any film formed during heat-treatment. The etching
4.6 Method 6, Carbonate Chromate Treatment—This pro-
solution is prepared by adding 1 gal (3.78 L) of concentrated
cess comprises treatment in a hot (180 to 190 °F (82 to 88 °C))
sulfuric acid and 45 oz (1.28 kg) of chromium trioxide to 9 gal
dilute solution of sodium carbonate and potassium chromate
(34 L) of water. It is used at a temperature of 160 to 180 °F (71
for periods from 2 to 20 min, followed by a water rinse. The
to 82 °C) (depending on the alloy and the amount of film) for
surface is then given a final treatment in hot 5% potassium
about 5 min and is followed by a water rinse. This treatment
dichromate solution, followed by a final rinse. The treatment
produces a passive surface suitable for painting under mild to
produces a thin, adherent, conversion coating on the surface,
intermediate exposure conditions and where clear finishes are
increasing the corrosion resistance of the metal and promoting
to be applied.
paint adhesion. This method is recommended for use under the
4.3 Method 3, Alcoholic Phosphoric Acid Cleaner—This
more severe conditions of service and for product finishes (see
treatment involves the use of an aqueous solution of phos-
Note 3 and Note 5).
phoric acid (10 to 15 volume %) with alcohol or other organic
4.7 Method 7, Amorphous Chromate Treatment—This pro-
solvents, together with wetting agents, emulsifying agents, etc.
c
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