Alkyd Coating System Guidelines
COATING SYSTEM NO. 27.00 – Alkyd Coating System Materials Specification, Performance-Based
1. Scope
1.1 This specification covers the requirements for an air-drying solvent-based alkyd coating system consisting of two or more coats of alkyd intended for use over blast cleaned steel (See Note 13.1.). The specification covers both the system and the individual coating requirements. The requirements are based primarily on the performance of the coating system.
1.2 The alkyd coating is suitable for exposure in Environmental Zones 1A (interior, normally dry), 1B (exterior, normally dry), 2A (frequently wet by fresh water, excluding immersion), and 2B (frequently wet by salt water, excluding immersion) (See Note 13.2.). The coating system is classified according to the drying time (fast, medium, slow) of the slowest drying coating layer.
2. Description
2.1 This multi-coat alkyd coating system specification does not cover coating systems comprised of water-reducible alkyds.
2.2 DRYING TIME: The alkyd coating shall be classified as Type 1 (fast drying), Type 2 (medium drying), or Type 3 (slow drying). See Section 6.4 regarding test methods and criteria for drying time.
2.3 FINISH COAT GLOSS: The finish coat shall be designated as flat, semigloss, or gloss in accordance with Section 7.3.
3. Referenced Standards
3.1 The latest issue, revision, or amendment of the referenced standards in effect on the date of invitation to bid shall govern, unless otherwise specified. Standards marked with an asterisk (*) are referenced only in the Notes, which are not requirements of this specification.
3.2 If there is a conflict between the requirements of any of the cited referenced standards and this specification, the requirements of this specification shall prevail.
3.3 SSPC STANDARDS AND JOINT STANDARDS:
Guide 13 Guide for the Identification and Use of Industrial Coating Systems in Computerized Product Databases:
PA 1 Shop, Field, and Maintenance Painting of Steel
PA 2 Measurement of Dry Coating Thickness with Magnetic Gages
SP 1 Solvent Cleaning
SP 5/NACE No. 1 White Metal Blast Cleaning Standard Method of Evaluating Degree of Rusting on Painted Steel Surfaces
3.4 AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM) STANDARDS:
A 36 Standard Specification for Carbon Structural Steel
A 607 Standard Specification for Steel, Sheet and Strip, High-Strength, Low-Alloy, Columbium or Vanadium, or Both, Hot-Rolled and Cold-Rolled (Withdrawn 2000; Replaced by A1008 and A1011/A1011M)
D 522 Standard Test Methods for Mandrel Bend Test of Attached Organic Coatings
D 523 Standard Test Method for Specular Gloss
D 562 Standard Test Method for Consistency of Paints Measuring Krebs Unit (KU) Viscosity Using a Stormer-type Viscometer
D 714 Standard Test Method for Evaluating Degree of Blistering of Paints
D 823 Standard Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels
D 1296 Standard Test Method for Odor of Volatile Solvents and Diluents
D 1475 Standard Test Method for Density of Liquid Coatings, Inks, and Related Products
D 1535 Standard Practice for Specifying Color by the Munsell System
D 1640 Standard Test Methods for Drying, Curing, or Film Formation of Organic Coatings at Room Temperature
D 1654 Standard Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments
D 2369 Standard Test Method for Volatile Content of Coatings
D 2371 Standard Test Method for Pigment Content of Solvent-Reducible Paints
D 2621 Standard Test Method for Infrared Identification of Vehicle Solids from Solvent-Reducible Paints
D 3359 Standard Test Methods for Measuring Adhesion by Tape Test
D 3363 Standard Test Method for Film Hardness by Pencil Test
D 3925 Standard Practice for Sampling Liquid Paints and Related Pigmented Coatings
D 4417 Standard Test Methods for Field Measurement of Surface Profile of Blast Cleaned Steel
D 4585 Standard Practice for Testing the Water Resistance of Coatings Using Controlled Condensation
D 4940 Standard Test Method for Conductimetric Analysis of Water-Soluble Ionic Contamination of Blasting Abrasives
D 5894 Standard Practice for Cyclic Salt Fog/UV / Exposure of Painted Metal, (Alternating Exposures in a Fog/Dry Cabinet and a UV/Condensation Cabinet)
3.5 AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI) STANDARD: Z129.1 Hazardous Industrial Chemicals-Precautionary Labeling
3.6 FEDERAL SPECIFICATIONS AND STANDARDS:
FED-STD-141 Paint, Varnish, Lacquer and Related Materials: Methods of Inspection, Sampling and Testing
Method 3011 Condition in Container Method 3021 Skinning (Partially Filled Container) Method 4321 Brushing Properties Method 4331 Spraying Properties Method 4541 Working Properties and Appearance of
Dried Film
4. Composition Requirements of Coating
4.1 RESIN REQUIREMENT: The resin component (nonvolatile vehicle) shall be a minimum of 50% by weight of alkyd. An alkyd resin is defined as a resin system primarily derived from the esterification reaction product of a polyhydric alcohol and a polybasic acid, fatty acid, or oil. The specification permits latitude to the coating supplier in the choice of alkyd resins. Modified alkyd resins, including cross reaction products with other common resin forming polymers, are allowed. These include, but are not restricted to, urethane modified alkyd resins and alkyd phenolic resins(See Note 13.3.).
4.2 PIGMENT REQUIREMENT: Lead or chromate based pigments are prohibited (See Note 13.4.).
5. Standard Testing Conditions
5.1ATMOSPHERIC CONDITIONS: When testing the paint and its application, the temperature under which it is applied and cured shall be 23 ± 2°C (73.5 ± 3.5°F).
5.2 SUBSTRATE: The hot rolled steel test panels shall conform to ASTM A 670, Grade 50 (See Note 13.5.).
5.3 TEST PANELS: Steel test panels measuring 75 mm x 150 mm x 3.2 mm (3 inch x 6 inch x 1/8 inch) or greater shall be blast cleaned to SSPC-SP 5/NACE No. 1. Test panels shall be solvent cleaned in accordance with SSPC-SP 1 prior to blast cleaning. The type of blast media shall be clearly identified and have conductivity less than 100 µS per ASTM D 4940. The panels shall have a nominal anchor pattern of 50 ± 25 µm (2.0 ± 1.0 mils) per ASTM D 4417.
5.4 APPLICATION: Apply the paint at the atmospheric conditions described in Section 5.1 in accordance with SSPC-PA 1 by spray to the front of the test panels. (See Note 13.6.) The number of coats shall be selected to match the manufacturerʼs recommendations.
5.5 DRY FILM THICKNESS: The dry film thickness (DFT) shall be within the manufacturerʼs written recommended range per coat and shall not exceed the stated minimum by more than 25 micrometers (1 mil). If there is no recommended film thickness, then the thickness shall be 50 ± 13 micrometers (2.0 ± 0.5 mils) per coat. The film thickness shall be measured in accordance with SSPC-PA 2 (See Note 13.7.).
5.6 CURE: Prior to any exposure testing, all panels shall be cured for a minimum of 14 and a maximum of 30 days at 16 to 27°C (60 to 80°F) and 35 to 65% relative humidity after application of the final coat.
5.7 SCRIBING: Scribe two parallel lines on the face of the coated panels so as to expose the underlying metal before testing. The lines shall be at least 1.2 cm (0.5 inch) from the edge, the top, and the bottom of each panel and at least 5 cm (2 inches) from each other. Each scribe shall be at least 6 cm (2.4 inches) long. The scribes may run vertically or at an angle across the face of the panel. Follow the scribe-making procedure described in ASTM D 1654.
6. Requirements of Liquid Coating
6.1 WORKING PROPERTIES: The paint shall be easily applied by brush, roller, or spray when tested in accordance with FED-STD-141, Methods 4321, 4331, and 4541. The paint shall show no streaking, running, or sagging during application or while drying.
6.2 CONDITION IN CONTAINER: The paint shall show no thickening, curdling, gelling, or hard caking when tested as specified in FED-STD-141, Method 3011, after storage for six months from the date of delivery, in a full, tightly covered container, at a temperature of 10 to 43°C (50 to 110°F).
6.3 SKINNING: There shall be no skinning in a three-quarters filled closed container after 48 hours when tested in the standard manner specified in FED-STD-141, Method 3021.
6.4 DRYING TIME
6.4.1 Drying time for each coating shall be the dry-hard time as measured in accordance with ASTM D 1640. The coating system shall be classified according to the maximum drying time of the slowest drying coating as follows:
6.4.2 Type 1 — Fast Drying: Less than or equal to 8 hours
6.4.3 Type 2 — Medium Drying: 9 to 16 hours
6.4.4 Type 3 — Slow Drying: 17 to 36 hours
7. Laboratory Physical Tests of Applied Films
7.1 FLEXIBILITY OF COATING SYSTEM: Prepare three test panels in accordance with Sections 5.1, 5.4, 5.5, and 5.6. The substrate shall be cold rolled strip 0.8 mm (1/32 inch) (22 gage) thick. Surface preparation shall be SSPC-SP
1. Recommended panel size is 100 mm x 150 mm (4 inch x 6 inch). Test triplicate panels in accordance with ASTM D 522. The elongation of each panel shall be a minimum of 28 percent using Test Method A or, if Test Method B is used, each replicate panel must exhibit no cracking when bent over a 3.2 mm (1/8 inch) diameter mandrel.
7.2 HARDNESS OF COATING SYSTEM: Prepare three test panels in accordance with Sections 5.1, 5.4, and 5.5. The substrate shall be any suitable thin gage [minimum 1.6 mm (1/16 inch)] steel panels. Surface preparation shall be SSPC-SP
1. Each panel shall exhibit minimum pencil hardness of 3B in accordance with ASTM D 3363 after 30 days air-dry at ambient temperature following the application of the final coat.
7.3 GLOSS: The specular gloss of the finish coat shall be tested in accordance with ASTM D 523. A flat alkyd finish coat shall have a maximum 85 degree specular gloss of 10. A semigloss alkyd finish coat shall have a 60 degree specular gloss between 30 and 60. A gloss alkyd finish coat shall have a 60 degree specular gloss greater than 60. Gloss of the primer and the intermediate coats shall be such that adequate adhesion shall occur between coats.
7.4 ADHESION: Prepare one panel in accordance with Sections 5.1 through 5.6. Perform the adhesion tape test in accordance with ASTM D 3359 at three different locations on the panel. Each test shall have a rating of 5A or 5B. For films thicker than 125 µm (5 mils), use Test Method A of ASTM D 3359.
8. Accelerated Laboratory Weathering Tests
8.1 CONDENSING HUMIDITY CABINET TEST: Prepare triplicate panels in accordance with Sections 5.1 through 5.6. Expose the panels for 500 hours in a condensation cabinet in accordance with ASTM D 4585.
8.1.1 Rust Evaluation: After 500 hours, each of the replicates shall have a minimum rust rating of 9 per SSPC-VIS2.
8.1.2 Blister Evaluation: After 500 hours, blister ratings for each of the three specimens shall be no worse than No. 8 Few per ASTM D 714. (See Note 13.8.)
8.2 CYCLIC SALT FOG/UV EXPOSURE TEST: Prepare triplicate panels in accordance with Section 5. Coat and seal all edges and the back side of each panel with a coating or masking that will provide the necessary protection to these surfaces. Expose the panels in accordance with ASTM D 5894 for 1008 hours (6 weeks).
8.2.1 Rust Evaluation: After 1008 hours, each test panel shall have a minimum rust rating of 9 per SSPC-VIS 2.
8.2.2 Blister Evaluation: After 1008 hours, each test panel shall have a blister rating of 10 (no blisters) per ASTM D 714.
8.2.3 Scribe Undercutting Evaluation: After 1008 hours, measure the maximum undercutting from the center of the scribe at any point along the scribe on both sides of each scribe. Each scribe will thus provide two data points: the maximum undercutting on the right side of the scribe and the maximum undercutting on the left side of the scribe. Three replicate panels, each with two scribes, will provide 12 data points. Compute the mean (average), x’, and the standard deviation, s, of these 12 data points. The scribe undercutting test parameter, U, is the mean plus two standard deviations (U = x’ + 2s). The scribe undercutting test parameter, U, rounded to the nearest millimeter, shall be less than or equal to 12 mm.
9. Material Quality Assurance
9.1 If the user chooses, tests may be used to determine the acceptability of a lot or batch of a qualified coating (See SSPC-PS 27.00 June 1, 2000 Editorial Revisions November 1, 2004 Note 13.9.).
10. Labeling
10.1 Labeling shall conform to ANSI Z129.1.
10.2 Technical data shall be provided for at least all data elements categorized as “essential” in SSPC-Guide13.
11. Inspection
11.1 All coatings supplied under this specification are subject to timely inspection by the purchaser or his authorized representative. The purchaser shall have the right to reject any materials supplied which are found to be defective under this specification. (See Note 13.9.) In case of dispute, unless otherwise specified, the arbitration or settlement procedure established in the procurement documents shall be followed. If no arbitration or settlement procedure is established, then a procedure mutually agreeable to purchaser, material supplier, and contractor shall be used.
11.2 Samples of paints under this painting system may be requested by the purchaser and shall be supplied upon request along with the manufacturerʼs name and identification for the materials. Samples may be requested at the time the purchase order is placed or may be taken from unopened containers at the job site.
11.3 Unless otherwise specified, the sampling shall be in accordance with ASTM D 3925.
12. Disclaimer
12.1 While every precaution is taken to ensure that all information furnished in SSPC standards and specifications is as accurate, complete, and useful as possible, SSPC cannot assume responsibility nor incur any obligation resulting from the use of any materials, coatings, or methods specified herein, or of the specification or standard itself.
12.2 This specification does not attempt to address problems concerning safety associated with its use. The user of this specification, as well as the user of all products or practices described herein, is responsible for instituting appropriate health and safety practices and for insuring compliance with all governmental regulations.
13. Notes
Notes are not requirements of this specification.
13.1 The alkyd coating system described may be suitable on hand cleaned steel. Consult manufacturer for performance or other data supporting this usage.
13.2 SSPC Environmental Zones covered in this specification are as follows:
Zone 1A: Interior, normally dry (or temporary protection). Very mild (oil base coating system now last six years or more).
Zone 1B: Exteriors, normally dry (includes most areas where oil base coatings now last six years or more).
Zone 2A*: Frequently wet by fresh water. Involves condensation, splash, or spray. (Oil base coatings now last five years or less.)
Zone 2B*: Frequently wet by salt water. Involves condensation, splash, or spray. (Oil base coatings now last three years or less.)
* Zones 2A and 2B have been modified to exclude immersion.
13.3 VOC Content: Each coating, after recommended thinning, must conform to published government regulations regarding volatile organic compound (VOC) content. VOC information should be supplied on the label or the technical data sheet. Various governmental agencies may have different VOC limits or use different methods of testing. The owner may modify this specification as necessary to specify a particular VOC content consistent with local regulations. Coatings meeting the composition and performance requirements of this specification usually have a maximum VOC level of 450 g/L (3.8 lb/gal).
13.4 Methods of cleaning considered better than SSPC-SP 6/NACE No. 3 include SSPC-SP 5/NACE No. 1 and SSPC-SP 10/NACE No. 2. In some instances, SSPC-SP 12/NACE No. 5 and SSPC-SP 11 have been shown to perform comparably with SSPC-SP 6/NACE No. 3. Pickled surfaces (SSPC-SP 8) and surfaces cleaned by water jetting (SSPC-SP 12/NACE No. 5) may not have a sufficiently high profile or surface roughness to meet the coating manufacturer’s requirement.
13.5 ASTM A 36 steel is frequently used; however, the specifier should be aware that ASTM A 36 steel may vary in chemical composition and hardness, which can affect blast profile and corrosion resistance.
13.6 Standard practices for automatic spray machine application as well as for hand held spray gun application are given in ASTM D 823.
13.7 Coating thickness measurement by the technique described in SSPC-PA 2 compensates for variation in surface profile and results in the coating thickness being measured above the magnetic average of the peaks of the anchor pattern.
13.8 Smaller size blisters are not considered to be as detrimental as larger blisters. Hence, a rating of No. 8 Few would be better than a rating of No. 6 Few.
13.9 QUALITY ASSURANCE TESTS: The quality assurance tests are used to determine whether the supplied products are of the same type and quality as those originally tested and certified for acceptance. The selected tests should accurately and rapidly measure the physical and chemical characteristics of the coating system necessary to verify that the supplied material is substantially the same as the previously accepted material. All of the quality assurance tests must be performed on the originally submitted qualification sample. The results of these tests are used to establish pass/fail criteria for quality assurance testing of supplied products.
13.9.1 Establishing Quality Assurance Acceptance Criteria: Many ASTM test methods contain precision and bias statements. Specification developers should be cognizant of the fact that these statements exist. Quality assurance test criteria should not be more stringent than the inter-laboratory precision of the test methods used. For example a common quality assurance test is weight per gallon as measured by ASTM D 1475.
The inter-laboratory reproducibility at the 95% confidence level tells us that any two measurements that differ by more than 1.8% should be considered suspect. This only represents the precision of the measurement technique and does not account for normal variances in the manufactured product. A reasonable estimate for this batch to batch variance might be 2%. The batch to batch variance and the potential variance attributable to the measurement technique are additive. A paint that was originally accepted with a weight per gallon of 10 pounds would therefore be acceptable within the range 9.62 to 10.38 pounds per gallon (10 + 3.8%).
Example: A common quality assurance test is density (weight per gallon) as measured by ASTM D 1475. The inter-laboratory reproducibility at the 95% confidence level tells us that because of errors associated with the method, any two measurements of the same material can differ by as much as 1.8%, without the measurements being considered suspect. This only represents the precision of the measurement technique and does not account for normal variances in the manufactured product.
The acceptable range for paint density must be stated. For example, a composition specification may state this requirement as 10.0 ± 0.2 lb/gal, 10.0 lb/gal ± 2%, or as a range from 9.8 to 10.2 lb/gal. The manufacturer of proprietary products should provide this information. Using these values, if the manufacturer’s lab measures the density to be 9.8 lb/gal, the product meets the specification and the paint is shipped to the job. Because of the lab to lab variation of 1.8%, the userʼs lab may measure the density of this sample to be as low as 9.8 less 1.8% of 9.8 (equals 9.6) lb/gal. Similarly for the high end, the manufacturer may measure density of 10.2 lb/gal while the user measures 10.2 plus 1.8% of 10.2 (equals 10.4) lb/gal. The pass/fail criteria for the user to accept a batch of paint should therefore be 9.6 to 10.4 lb/gal.
Where precision and bias data are not available for a given test method, determine the standard deviation of a minimum of five measurements taken on the originally tested and certified material. The pass/fail criterion is that the measurement of the test sample shall fall within two standard deviations of the target value. The contracting parties must agree on a target value.
13.9.2 Recommended Quality Assurance Tests: Recommended quality assurance tests include but are not limited to, infrared analysis (ASTM D 2621), viscosity (ASTM D 562), weight per gallon (ASTM D 1475), total solids (ASTM D 2369), dry time (ASTM D 1640), percent pigment (ASTM D 2371), gloss (ASTM D 523), color (ASTM D 1535), condition in container (Fed. Std. 141, Method 3011), and odor (ASTM D 1296).
13.10 The procurement documents should establish the responsibility for samples, testing, and any required affidavit certifying full compliance with the specification.
COATING SYSTEM NO. 27.00 – Alkyd Coating System Materials Specification, Performance-Based
