ASTM D3003-01(2022)

Standard Test Method for Pressure Mottling and Blocking Resistance of Organic Coatings on Metal Substrates

ABSTRACT
This test method covers the procedures for determining the pressure mottling and sticking, or blocking resistance of organic coatings applied on coil-coated or factory coated metal substrates prior to fabrication. The coated metal is cut into at least four, preferably six, suitably-sized panels which are then subjected to a specified pressure and temperature for a specified time. After the heat is turned off and the specimen cooled, the samples are examined for any signs of sticking or blocking and mottling.
SCOPE
1.1 This test method covers determination of the pressure mottling and sticking, or blocking resistance of organic coatings applied to coil-coated or factory-coated metal prior to fabrication.  
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.3 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

• Status: Published
• Publication Date: 30-Nov-2022
• ICS: 25.220.60 - Organic coatings
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.53 - Coil Coated Metal

Overview

ASTM D3003-01(2022) establishes a standardized test method for evaluating the pressure mottling and blocking resistance of organic coatings applied to metal substrates, specifically those that are coil-coated or factory-coated before fabrication. These key surface qualities impact both the manufacturing process and service life of coated metal products. The standard ensures objective measurement and reporting of any tendency for coated surfaces to stick (block) together under heat and pressure, as well as observing surface pattern changes (pressure mottling).

By following this ASTM method, manufacturers, quality control labs, and buyers can reliably assess coating performance prior to forming, bending, or otherwise fabricating metal parts. The procedure provides clear criteria for grading both blocking and mottling, supporting informed decisions and contract agreements.

Key Topics

• Pressure Mottling: Assesses the tendency for organic coatings to develop uneven patterns or gloss changes under pressure and heat, which can negatively affect appearance and performance.
• Blocking Resistance (Sticking): Evaluates if coated metal panels adhere or stick together when subjected to pressure and elevated temperature, which can cause damage or handling issues during fabrication.
• Test Procedures: Involves cutting representative panels from coated stock, stacking them, and applying a defined pressure and temperature for a specified time before grading.
• Assessment Criteria: Uses a 0 to 10 grading scale for both blocking and mottling, providing precise classification from perfect performance (10) to severe sticking or mottling (0).
• Reporting Requirements: Specifies the need to document test equipment, conditions, specimen details, and results, ensuring consistency and traceability.

Applications

• Quality Control for Coil-Coated Metals: Enables manufacturers to verify the quality and durability of organic coatings before parts are fabricated, reducing the risk of surface defects or product rejections.
• Product Development and Optimization: Supports R&D efforts to improve or compare new coating formulations, by offering a consistent method to test blocking resistance and mottling across different products.
• Supplier and Buyer Agreements: Serves as a reference method in contracts, ensuring both parties agree on acceptable performance levels for coated metal substrates.
• Regulatory and Compliance Assessments: Assists organizations in demonstrating that coatings meet international standards and customer requirements, facilitating global market access.

Related Standards

• ASTM D3359 - Standard Test Methods for Measuring Adhesion by Tape Test
• ASTM D522 - Standard Test Methods for Mandrel Bend Test of Attached Organic Coatings
• ASTM D4145 - Standard Test Method for Coating Flexibility of Prepainted Sheet
• ISO 2812 - Paints and Varnishes - Determination of Resistance to Liquids
• ISO 6272 - Paints and Varnishes - Rapid-Deformation (Impact Resistance) Tests

ASTM D3003-01(2022) plays a key role in the evaluation of coating performance on metal, prioritizing both aesthetic and functional durability for coil-coated and factory-coated substrates. The standardized approach to determining blocking resistance and pressure mottling builds consistency in production, enhances product value, and strengthens confidence within the coatings industry.

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:D3003 −01(Reapproved 2022)
Standard Test Method for
Pressure Mottling and Blocking Resistance of Organic
Coatings on Metal Substrates
This standard is issued under the fixed designation D3003; 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.
1. Scope specimensareexaminedforanysignsofsticking(orblocking),
and mottling.The results are rated on the 0 to 10 scale and may
1.1 This test method covers determination of the pressure
beusedinacceptingorrejectingthecoatinginaccordancewith
mottling and sticking, or blocking resistance of organic coat-
standards established between the purchaser and the seller.
ings applied to coil-coated or factory-coated metal prior to
fabrication.
4. Apparatus
1.2 The values stated in SI units are to be regarded as the
4.1 Suitable Hydraulic or Mechanical Press or Vise may be
standard. The values given in parentheses are for information
used.Theequipmentshallbecapableofproducingtherequired
only.
test pressure in kilopascals (or pounds-force per square inch)
1.3 This standard does not purport to address all of the
and be equipped with a suitable device for measuring the force
safety concerns, if any, associated with its use. It is the
applied.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
5. Test Specimens and Conditions
mine the applicability of regulatory limitations prior to use.
5.1 At least four, and preferably six, flat panels shall be cut
1.4 This international standard was developed in accor-
from the coated stock, the age of which shall be within the
dance with internationally recognized principles on standard-
limits agreed upon between the purchaser and the seller.
ization established in the Decision on Principles for the
5.2 Panels should be at least 100 mm by 70 mm (4 in. by
Development of International Standards, Guides and Recom-
2.5 in.) to provide an adequate area for assessing the results.
mendations issued by the World Trade Organization Technical
Where the equipment does not provide adequate pressure,
Barriers to Trade (TBT) Committee.
smaller panels may be used. The minimum recommended size
2. Terminology is 50 mm by 50 mm (2 in. by 2 in.).
2.1 Definitions of Terms Specific to This Standard: 5.3 Use only flat panels. If necessary, file the edges smooth
2.1.1 blocking or sticking, n—the condition wherein coated to ensure maximum contact between the surfaces. When the
surfaces adhere to each other. equipment permits, panels larger than the pressure plates may
be used, thus eliminating any effect from uneven edges. With
2.1.2 pressure mottling, n—film distortion or uneven pattern
this method, the kilopascals (or pounds of force per square
giving a change of gloss and nonuniform appearance. It is
inch)iscalculatedusingonlythepanelareawithinthepressure
usually caused by pressures within a painted coil or stacked
plates.
painted sheets or other painted products.
5.4 The film thickness of the coating under test shall be as
3. Summary of Test Method
specified or agreed upon between the purchaser and the seller.
3.1 The coated metal is cut into suitably sized panels. A
5.5 The coated stock shall be tested under the conditions of
stack of these panels is then subjected to a specified pressure
pressure, temperature, and time mutually agreed upon between
and temperature for a specified time to permit any pressure
the purchaser and the seller. Pressures ranging from 750 kPa to
mottling and sticking or blocking to develop. The applied heat
2400 kPa (110 psi to 350 psi), temperatures from 43 °C to
of the test apparatus is turned off and, after cooling, the
60 °C (110 °F to 140 °F), and times of 2 h to 16 h have been
used.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.53 on Coil Coated Metal. Suitable equipment includes presses and drill press vises modified for use with
Current edition approved Dec. 1, 2022. Published December 2022. Originally a torque wrench if agreed upon between purchaser and seller (Hensley, W. L.,
approved in 1971. Last previous edition approved in 2016 as D3003 – 01 (2016). “Pressure Mottling Test,”Journal of Paint Technology, Vol 40, No. 517, February
DOI: 10.1520/D3003-01R22. 1968, p. 54A).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3003−01(2022)
5.6 In the absence of agreed or specified test conditions, a 6.7 Maintain panels that are to be reassessed for a mottling
pressure of 750 kPa 6 35 kPa (110 psi 6 5 psi), a temperature grade in accordance with Table 1 after a 24-h recovery period
of 43 °C 6 1.5 °C (110 °F 6 3 °F), and a time of 16 h shall be at 24 °C 6 3 °C (75 °F 6 5 °F).
used.
6.8 For both properties assign each coating a grade that is
5.7 The total force applied is measured by a suitable gage the arithmetic mean of all panels tested.
and the pounds of force per kilopascals (or square inch) is
7. Report
calculated by dividing the force by the area in square inches of
7.1 Report the following information for each coating:
one side of one panel.
7.1.1
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