ASTM D1731-67(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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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 1731 – 67 (Reapproved 1998)
Standard Practices for
Preparation of Hot-Dip Aluminum Surfaces for Painting
This standard is issued under the fixed designation D 1731; 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.
1. Scope 4.3 Method 2—Solvent spray cleaning in accordance with
Method A, Procedure 1 of Practice D 609.
1.1 These practices describe procedures for the preparation
4.4 Method 3—Vapor degreasing in special equipment in
of hot-dip aluminum surfaces for painting.
accordance with the latest revision of Method A, Procedure 2
1.2 This standard may involve hazardous materials, opera-
of Practice D 609, employing trichlorethylene or perchloreth-
tions, and equipment. This standard does not purport to
ylenevapor.Solventcleaningdoesnotdisturbthenaturaloxide
address all of the safety problems associated with its use. It is
film on the metal and may prove adequate for some applica-
the responsibility of whoever uses this standard to consult and
tions.
establish appropriate safety and health practices and deter-
mine the applicability of regulatory limitations prior to use.
5. Chemical Treatment
2. Referenced Documents 5.1 The surfaces may be prepared for painting by any of the
methods for chemical treatment (Note 1) described in 5.2 to
2.1 ASTM Standards:
5.9:
D 609 Practice for Preparation of Cold-Rolled Steel Panels
for Testing Paint, Varnish, Lacquer, Conversion Coatings
NOTE 1—Materials and procedures employed in these methods of
and Related Coating Products
treatment are available from a number of sources as proprietary com-
pounds or methods. Selection may be made from available sources.
3. Types of Surface Preparations
5.2 Method 1, Alkaline Cleaners—Etching alkaline solu-
3.1 Two types of surface preparations are covered as fol-
tions, such as caustic soda, should be avoided because of the
lows:
possibility of dissolving away the aluminum coating thereby
3.1.1 Solvent Cleaning, and
exposing the base metal. Since inhibited alkaline cleaners do
3.1.2 Chemical Treatments.
notetchthesurface,theycanbeusedtoremovegrease,oil,and
3.2 These two types cover several methods as described in
other organic solids from hot dip aluminum. After alkali
Section 5. Variations in surface treatment produce end condi-
cleaning, the surface should be thoroughly rinsed with clean
tions which differ and which do not necessarily yield identical
water. Most often alkaline-cleaned surfaces are subsequently
results when paints are applied. Service conditions will dictate
processed by one of the following methods, described in
the type of surface preparation that should be selected.
5.3-5.9:
5.3 Method 2, Alcoholic Phosphoric Acid Cleaners—This
4. Solvent Cleaning
treatment involves the use of an aqueous solution of phospho-
4.1 The surfaces may be prepared for painting by any of the
ric acid with alcohol or other organic solvents, together with
methods for solvent cleaning described in 4.2 and 4.3.
wetting agents, emulsifying agents, etc. The solution may be
4.2 Method 1—Manual swabbing or dip washing with a
applied by swabbing or dipping (preferably at a temperature of
solvent such as mineral spirits or high flask solvent naphtha. It
70 to 90°F (21 to 32°C)). The solution should remain on the
is extremely difficult to produce a clean metal surface by this
surface for several minutes, followed by thorough rinsing with
method. Accumulated contaminants in the solvent or on the
clean water. A very thin phosphate film is formed which tends
swab are frequently redeposited on the surface being prepared.
to protect the metal and promote paint adhesion.
NOTE 2—Materials meeting the requirements of the latest revision of
U.S. Military Specification MIL-M-10578B may be used.
These practices are under the jurisdiction ofASTM Committee B-8 on Metallic
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.07 in
5.4 Method 3, Acid Fluoride Deoxidizer—This treatment
Chemical Conversion Coatings.
includes the use of nitric or sulfuric acid with chromium
Current edition approved Sept. 8, 1967. Published November 1967. Originally
trioxide and a fluoride. It provides a clean and uniform surface
published as D 1731 – 60. Last previous edition D 1731 – 66.
Annual Book of ASTM Standards, Vol 06.01. without undue roughening and is effective for removing
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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 1731
inorganic soils and any film formed during the production of lowed by a final rinse.The treatment produces a thin, adherent,
the hot dip aluminum. The deoxidizing solution is generally conversion coating on the surface, increasing the corrosion
used at a temperature of 70 to 130°F (21 to 54°C) (depending resistance of the metal and promoting paint adhesion (Note 3).
on the alloy and the amount of
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