ASTM D1730-67(1998)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation: D 1730 – 67 (Reapproved 1998)
Standard Practices for
Preparation of Aluminum and Aluminum-Alloy Surfaces for
Painting
This standard is issued under the fixed designation D 1730; 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 (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. Scope With this method it is extremely difficult to prevent accumu-
lation of contaminants on the swab or in the solvent. This
1.1 These practices cover four types of treatment for prepa-
method is only recommended when other treatments are
ration of aluminum and aluminum-alloy surfaces for painting,
impractical.
as follows:
3.1.2 Method2,SolventSprayCleaning, in accordance with
1.1.1 Type A—Solvent Cleaning.
Method A, Procedure 1 of Practice D 609.
1.1.2 Type B—Chemical Treatments.
3.1.3 Method 3, Vapor Degreasing, in special equipment
1.1.3 Type C—Anodic Treatments.
employing trichloroethylene vapor, in accordance with Method
1.1.4 Type D—Mechanical Treatments. These four types
A, Procedure 2 of Practice D 609.
cover a number of procedures, as described herein.
1.2 Variations in surface treatment produce end conditions
4. Type B—Chemical Treatments
which differ, and which do not necessarily yield identical
NOTE 1—Materials and procedures employed in these methods of
results when paints are applied. Service conditions will dictate
treatment are available from a number of sources as proprietary com-
the type of surface preparation that should be selected, al-
pounds or methods. Selection may be made from available sources.
though the quality produced by any individual method may
4.1 Method 1, Alkaline Cleaners—Alkaline solutions, such
vary with different alloys.
as caustic soda, etch the metal, thus destroying the natural
1.3 This standard may involve hazardous materials, opera-
oxide film. They are followed by an acid treatment, preferably
tions, and equipment. This standard does not purport to
nitric acid or phosphoric acid. They shall not be used on
address all of the safety problems associated with its use. It is
assembledstructures.Inhibitedalkalinecleanersaresometimes
the responsibility of whoever uses this standard to consult and
employedasapretreatmenttoremovegreaseandoilpriortoan
establish appropriate safety and health practices and deter-
acid treatment. Inhibited alkaline cleaners do not etch the
mine the applicability of regulatory limitations prior to use.
surface. They are not generally recommended unless followed
2. Referenced Documents
by a conversion treatment, such as described in Methods 4, 5,
6, or 7.
2.1 ASTM Standards:
4.2 Method 2, Sulfuric Acid, Chromium Trioxide Etch—
D 609 Practice for Preparation of Cold-Rolled Steel Panels
This treatment provides a clean and uniform surface without
for Testing Paint, Varnish, Lacquer, Conversion Coatings
undue etching, and is effective for removing oil and water
and Related Coating Products
stains and any film formed during heat-treatment. The etching
3. Type A—Solvent Cleaning
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
3.1 Solvent cleaning does not disturb the natural oxide film
(34 L) of water. It is used at a temperature of 160 to 180°F (71
on the metal and may prove adequate for some applications,
to 82°C) (depending on the alloy and the amount of film) for
such as ambient indoor or very mild service conditions. Three
about 5 min and is followed by a water rinse. This treatment
methods may be employed, as follows:
produces a passive surface suitable for painting under mild to
3.1.1 Method 1, Manual Swabbing or Dip-Washing, with a
intermediate exposure conditions and where clear finishes are
solvent such as mineral spirits or high-flask solvent naphtha.
to be applied.
4.3 Method 3, Alcoholic Phosphoric Acid Cleaner—This
These practices are under the jurisdiction ofASTM Committee B-8 on Metallic
treatment involves the use of an aqueous solution of phospho-
and Inorganic Coatings and is the direct responsibility of Subcommitee B08.07 on
ric acid (10 to 15 volume %) with alcohol or other organic
Chemical Conversion Coatings.
solvents, together with wetting agents, emulsifying agents, etc.
Current edition approved Sept. 8, 1967. Published November 1967. Originally
published as D 1730-60. Last previous edition D 1730-66.
The solution may be applied by swabbing or dipping at room
Annual Book of ASTM Standards, Vol 06.01.
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
D 1730 – 67 (1998)
temperature (70 to 90°F (21 to 32°C)), and should be allowed celerating agents such as fluoride-containing materials. The
to remain on the surface for several minutes, followed by aluminum surface is converted to an adherent, amorphous,
thorough rinsing with clean water. A very thin phosphate film mixedmetallicoxidecoating,irridescentgoldentolight-brown
is formed which tends to protect the metal and promote paint in color, which increases the corrosion-resistance and the
adhesion under mild to intermediate exposure conditions. adherence and durability of any applied paint film. This
method is recommended for use under the more severe
NOTE 2—U.S. Military Specification MIL-M-10578B describes a treat-
conditions of service and for product finishes. The coating
ment of this type.
process may be carried out by immersion, spray, or brush
4.4 Method 4, Crystalline Phosphate Treatment—This
application, at room temperature (70 to 90°F (21 to 32°C)), in
surface-coating method consists in reacting the aluminum
from 15 s to 5 min contact time (see Note 3 and Note 5).
surface in a zinc-acid-phosphate solution containing oxidizing
4.8 Method 8, Acid-Bound Resinous Treatment (see Note
agents and other salts for accelerating the coating action. The
6)—This surface treatment involves the use of a suitably
aluminum surface is converted to a finely crystalline, phos-
applied acid-bound resinous film of approximately 0.3 to 0.5
phate coating of the proper texture adapted to inhibit corrosion
mils(7.6to12.7µm)thickness.Thetreatmentisbasedonthree
and increase the adherence and durability of any applied paint
primary components: a hydroxyl-containing resin; a pigment
film. It is recommended for product finishes. The phosphate
capable of reacting with the resin and an acid; and an acid
coating process may be carried out by immersion or spray
capable of insolubilizing the resin by reacting with the resin,
applicat
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