Zinc Dust Sacrificial Primer, Performance-Based

On Zinc Dust Sacrificial Primer

PAINT SPECIFICATION NO. 29 – Zinc Dust Sacrificial Primer, Performance-Based

1. Scope
1.1 This specification covers highly pigmented primers that contain zinc dust as the major pigment component (minimum 65% by weight in the dry film) and are defined by their ability to protect ferrous substrates.

1.2 The vehicle type may be inorganic (Type I) or organic (Type II).

1.3 Each primer type (I and II) is classified according to the level of exterior performance at a severe marine site. Laboratory performance criteria are also included.

1.4 This specification does not cover weldable pre-con­struction primers such as SSPC-Paint 30.

1.5 Zinc-rich coatings, both topcoated and untopcoated, have been used successfully in a wide variety of environmental zones. For a detailed breakdown of applicability of various types of zinc-rich coatings in different environmental zones, refer to SSPC-PS Guide 12.00. Consult the coating manufacturer for specific exposure recommendations (see Note 13.1).

1.6 This coating is intended for application by spray for use by itself or as a primer in a multi-coat system. 

2. Description
2.1 USE OF SPECIFICATION
2.1.1 Primers meeting this specification are categorized according to vehicle type and performance level.
2.1.2 If no vehicle type is specified, either Type I, inorganic, or Type II, organic, is acceptable (see Section 2.3).
2.1.3 If no performance level is specified, Level 1 is assumed (see Section 2.5).

2.2 COMPOSITION: The coating described in this specification consists of zinc dust, functional additives, and an organic or inorganic binder with appropriate solvents (see Note 13.2).

2.3 VEHICLE TYPES
2.3.1 Type I-A, inorganic post-curing vehicles—water soluble, include materials such as alkali metal silicates, phosphates, and modifications thereof which must be subsequently cured by application of heat or a solution of a curing compound (or curing solution).

2.3.2 Type I-B, inorganic self-curing vehicles—water ­reducible, include water soluble alkali metal silicates, quaternary ammonium silicates, phosphates, and modifications thereof. These coatings cure by a reaction among the zinc, silicate, steel substrate, and naturally occurring carbon dioxide during and after evaporation of water from the coating.

2.3.3 Type I-C, inorganic self-curing vehicles—solvent reducible, include titanates, organic silicates, and polymeric modifications of these silicates. These systems are dependent upon moisture from the atmosphere to complete hydrolysis, forming the titanate- or polysilicate-zinc reaction product.

2.3.4 Type II, organic vehicles covered by this specification, may be chemically cured or may dry by solvent evaporation (see Note 13.3). Under certain conditions, heat may be used to facilitate or accelerate drying and curing.

2.4 COMPONENTS: These zinc dust primers may consist of one, two, or three components.

2.5 EXTERIOR PERFORMANCE: The primer shall be classified as follows according to the minimum number of months of successful performance at a severe marine site (see Section 9.3):
Level 1: 12 months
Level 2: 30 months
The performance requirements of the coated test panels are summarized in Table 1.

3. Referenced Standards
3.1 The latest issue, revision, or amendment of the refer­enced documents in effect on the date of invitation to bid shall govern unless otherwise specified. Those documents marked with an asterisk (*) are referenced only in the Notes or the Appendix, which are not requirements of this specification.

3.2 If there is a conflict between the requirements of any of the cited referenced documents and this specification, the requirements of this specification shall prevail.
3.3 SSPC STANDARDS AND JOINT STANDARDS:

3.4 ASTM INTERNATIONAL STANDARDS:¹

A 572 Standard Specifi cation for High-Strength Low-Alloy Columbium-Vanadium Structural Steel
B 117 Practice for Operating Salt Spray (Fog) Apparatus
D 185 Test Methods for Coarse Particles in Pigments, Pastes, and Paints
D 520 Specification for Zinc Dust Pigment
* D 562 Test Method for Consistency Measuring Krebs Unit (KU) Viscosity of Paints Using a Stormer-type Viscometer
D 714 Test Method for Evaluating Degree of Blistering of Paints
* D 1141 Standard Practices for Substitute Ocean Water
* D 1296 Test Method for Odor of Volatile Solvents and Diluents
* D 1475 Test Method for Density of Liquid Coatings, Inks, and Related Products
* D 1535 Practice for Specifying Color by the Munsell System
* D 1640 Test Methods for Drying, Curing, or Film Formation of Organic Coatings at Room Temperature
D 1654 Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments
* D 2369 Test Method for Volatile Content of Coatings
* D 2371 Test Method for Pigment Content of Solvent-Reducible Paints
* D 2621 Test Method for Infrared Identification of Vehicle Solids from Solvent-Reducible Paints
D 3278 Test Methods for Flash Point of Liquids by Small-Scale Closed-Cup Apparatus
D 3359 Test Methods for Measuring Adhesion by Tape Test
D 3925 Practice for Sampling Liquid Paints and Related Pigmented Coatings
D 4417 Test Methods for Field Measurement of Surface Profile of Blast Cleaned Steel
* D 5894 Practice for Cyclic Salt Fog/UV Exposure of Painted Metal, (Alternating Exposures in a Fog/Dry Cabinet and a UV/Condensation Cabinet)
G 92 Practice for Characterization of Atmospheric Test Site
* G 154 Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials
* G 155 Practice for Operating Xenon Arc Light Apparatus for Exposure of Nonmetallic Materials

3.5 FEDERAL SPECIFICATIONS AND STANDARDS:²

FED-STD-141 Paint, Varnish, Lacquer and Related Materials: Methods of Inspection, Sampling and Testing
* Method 3011 Condition in Container
Method 4331 Spraying Properties
Method 4541 (Canceled) Working Properties and Appearance of Dried Film

3.6 AMERICAN ASSOCIATION OF STATE HIGHWAY AND TRANSPORTATION OFFICIALS (AASHTO) STANDARD:³

* M300 Inorganic Zinc Rich Primer

3.7 AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI) STANDARD:⁴

Z129.1 Hazardous Industrial Chemicals— Precautionary Labeling

4. Composition Requirements
4.1 The manufacturer is given wide latitude in the selection of materials and manufacturing processes.
4.2 PIGMENTATION
4.2.1 The major pigment component in these coatings is zinc dust of the type described in ASTM D 520 (see Note 13.4). The paint shall contain a minimum of 65% zinc dust pigment by weight in the dry film.
4.2.2 Other pigment components may include extenders, curing aids, tinting colors, and suspension and pot-life control agents.

¹ ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.

² FED STD 141 Available from USA Information Systems, Inc. 1092 Laskin Road, Suite 208, Virginia Beach, Va. 23451. This standard is available on-line from www.usainfo.com.

³ American Association of State Highway & Transportation Officials, 444 North Capitol Street N.W., Suite 249, Washington DC 20001.

⁴ American National Standards Institute, 1819 L Street, NW, Suite 600, Washington, DC 20036. Standards downloadable from www.ansi.org.

5. Standard Testing Conditions
5.1 TEST PANELS: The hot rolled steel test panels shall conform to ASTM A 572. Panel size shall be 100 mm x 150 x 3.2 mm (4 x 6 x 1/8 inches) or greater. Test panels shall be solvent cleaned in accordance with SSPC-SP 1 prior to blast cleaning. The test panels shall be blast cleaned in accordance with SSPC-SP 5 and have a blast profile of 44 to 57 micrometers (1.75 to 2.25 mils). Measure the blast profile in accordance with ASTM D 4417, Method C.
5.2 APPLICATION: The coating shall be spray-applied as a single coat in accordance with the manufacturer’s written recommendations.
5.3 DRY FILM THICKNESS: The dry film thickness (DFT) of the test panels shall meet the manufacturer’s written recom­mended minimum and shall not exceed the manufacturer’s stated minimum by more than 25 micrometers (1 mil). If there is no recommended film thickness, then the thickness shall be 60 to 90 micrometers (2.5 to 3.5 mils). The DFT shall be measured in accordance with Appendix 5 of SSPC-PA 2.
5.4 CURE: The coating shall be dried and cured in accor­dance with the manufacturer’s written recommendations. Before any testing, all coated panels shall be aged for a minimum of 30 days in an environment with a minimum relative humidity of 55%.
5.5 SCRIBING: Scribe two parallel lines on the face of the coated panels to expose the underlying metal before testing. The lines shall be at least 2.5 cm (1 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.
5.6 BACKS AND EDGES: Coat and seal all edges and the back side of each panel with a coating or tape that will provide the necessary protection to these surfaces.

6. Requirements of Liquid Coating
6.1 MIXING: The liquid portion of a multi-component coating shall be mixed and dispersed to produce a product that is uniform, stable, free from grit, and in conformance with the requirements of this specification.
6.1.1 The pigment portion of a multi-component coating (if supplied as a dust) shall be dry and loosely packed prior to mixing.
6.1.2 The ready-mixed coating shall be capable of being dispersed under mechanical agitation to a smooth, uniform consistency and shall not show any objectionable properties in the mix.
6.1.3 After mixing, all types of coarse particles and skins as residue retained on a standard 60 mesh screen shall be no more than 0.5% by weight of the total coating, regardless of type, in accordance with ASTM D 185. If required for new technology coatings, an alternate screen size may be agreed to among the contracting parties.
6.2 STORAGE LIFE: Neither the vehicle of the multi-­component coating nor the ready-mixed coating shall show thickening that is detrimental to performance or application properties. The components or coating shall exhibit no curdling, gelling, gassing, or hard caking after being stored unmixed for a minimum of six months from date of delivery in a tightly sealed, unopened container at a temperature of 10 to 32°C (50 to 90°F).
6.3 WORKING PROPERTIES: The mixed coating shall spray easily and show no signs of, streaking, running, sagging, or other objectionable features when applied within the coating manufacturer’s recommended film thickness range and tested in accordance with FED-STD 141, Methods 4331 and 4541.
6.4 FLASH POINT: The minimum flash point, as deter­mined by ASTM D 3278, should be “none” for inorganic water-based zinc dust coatings, and a minimum of 4.4°C (40°F) for solvent-based inorganic zinc primers (Type I) and for organic zinc primers (Type II).

7. Laboratory Physical Tests of Applied Films
7.1 MUDCRACKING: The coating, when applied and aged in accordance with Sections 5.1, 5.2, and 5.4 to a 125 micrometer (5 mil) minimum dry film thickness, shall show no signs of mudcracking visible to the eye unaided by magnification.
7.2 ADHESION: Adhesion requirements are summarized in Table 1.
7.2.1 Adhesion of Unaged Primer: The coating, when applied, dried, and cured in accordance with Section 5, shall be tested per ASTM D 3359, Method B. There shall be no separation of the coating or delamination of an entire square. Loss of adhesion around the perimeter due to cutting of each square is acceptable. The adhesion rating shall be no less than grade 4B.
7.2.2 Adhesion of Salt Fog Exposed Primer: Unscribed portions of the triplicate test panels exposed in the salt fog exposure test of Section 8.1 below shall be tested per ASTM D 3359, Method B within seven to 14 days after removal from the test chamber. The adhesion rating shall be no less than grade 3B.

8. Accelerated Laboratory Weathering Test
8.1 SALT FOG EXPOSURE TEST: Triplicate panels prepared in accordance with Section 5 shall be exposed in a salt fog cabinet in accordance with ASTM B 117. Inorganic coatings (Type I) shall be exposed for 3000 hours and organic coatings (Type II) shall be exposed for 1000 hours (see Notes 13.5, 13.6, and Table 1).
8.1.1 Rust Evaluation:After the specified exposure time, each replicate panel shall have no rusting of the coated portion. Slight rusting in the scribe mark is permissible and resulting staining should be ignored. Strips 6 mm (1/4 inch) wide along the edges of the panel may be ignored.
8.1.2 Blister Evaluation: After the specified exposure time, there shall be no blistering of the coated portion.
8.1.3 Scribe Evaluation: After the specified exposure time, there shall be no undercutting from the scribe.

9. Test Fence Exposure Performance
9.1 The coating system shall meet the requirements of Section 9.4.1 for Level 1 qualification and Section 9.4.2 for Level 2 qualification (see Table 1).
9.2 TEST PANEL PREPARATION: Prepare triplicate panels in accordance with Section 5.
9.3 EXPOSURE SITE REQUIREMENTS: The test panels shall be exposed on a test fence at a severe marine exposure site. The panels shall be inclined from 30 to 45 degrees from horizontal and shall face the seacoast or the equator. For purposes of this specification, a severe marine site is defi ned as one located within 30 meters (100 feet) of the mean low tide level at a seacoast location (see Note 13.7).
9.4 TEST FENCE EXPOSURE PERFORMANCE REQUIREMENTS
9.4.1 Level 1 Qualification: After a minimum of 12 months, the test specimens shall be examined for rusting (SSPC-VIS 2), blistering (ASTM D 714), and undercutting at the scribe (ASTM D 1654). (See Note 13.8.)
9.4.1.1 Inorganic zinc primers (Type 1) shall exhibit a rust rating of 10 on two of the specimens and a minimum rating of 9 on the third specimen. No blistering shall be observed. Slight rusting is permitted in the scribe. The maximum undercutting or rusting from the center of the scribe shall not exceed 0.8 mm (1/32 inch).
9.4.1.2 Organic zinc primers (Type II) shall exhibit a rust rating of 10 on two of the specimens and a minimum rating of 9 on the third specimen. No blistering shall be observed. Slight rusting is allowed in the scribe. The maximum undercutting or rusting from the center of the scribe shall not exceed 1.6 mm (1/16 inch).
9.4.2 Level 2 Qualification: After a minimum of 30 months, the test specimens shall be examined for rusting (SSPC-VIS 2), blistering (ASTM D 714), and undercutting at the scribe (ASTM D 1654).
9.4.2.1 Inorganic zinc primers (Type 1) shall have a minimum rust rating of 9 on each of the three panels. No blistering shall be observed. Slight rusting is allowed in the scribe. The maximum undercutting or rusting from the center of the scribe shall not exceed 1.6 mm (1/16 inch).
9.4.2.2 Organic zinc primers (Type II) shall exhibit a minimum of rust rating of 9 on each of the three panels. No blistering shall be observed. Slight rusting is allowed in the scribe. The maximum undercutting or rusting from the center of the scribe shall not exceed 3.2 mm (1/8 inch).

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-Guide 13.

11. Inspection
11.1 All materials 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 that are found to be defective under this speci­fication (see Notes 13.9 and 13.10). 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 the purchaser and material supplier shall be used.
11.2 Samples of painting systems may be requested by the purchaser and shall be supplied upon request along with the manufac­turer’s 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 specifi ed 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 ensuring compliance with all governmental regulations.

13. Notes
Notes are not requirements of this specification.
13.1 USES: This primer covers a range of vehicle types (inorganic/organic, water-borne/solvent-borne, one-pack/two­pack/three-pack, chemical curing/thermoplastic). A detailed description of environmental zone conditions is contained in Chapter 1 of the SSPC Painting Manual, Volume 2–Systems and Specifications, Eighth Edition. Consult SSPC-PS Guide 12.00 and coating manufacturers for specific uses and expo­sure limitations. PS Guide 12.00 does not address zinc dust loading. Caution should be used when zinc-rich coatings contact austenitic stainless steel. In case of fire, molten zinc metal may cause embrittlement of austenitic stainless steel.
13.2 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 limit consistent with local regulations. Coatings meeting the composition and performance requirements of this specification usually have a VOC level less than 500 g/L (4.2 lb/gal).
13.3 TYPE II, ORGANIC VEHICLE TYPES: Typical of this group of vehicles are phenoxies, catalyzed epoxies, epoxy esters, moisture curing polyurethanes, styrenes, silicones, and vinyls. This listing is not all-inclusive.
13.4 LEAD LEVEL IN ZINC DUST: ASTM D 520 speci­fies three types of zinc dust for use as a pigment in coatings. Type I is a general grade in which no maximum level of lead is specified. Type II is a high-purity grade with a maximum lead level of 0.01% by weight. Type III is the highest purity grade, with a maximum lead level of 0.002% by weight. Any grade of zinc dust can be used in the zinc coatings covered by this specification. However, it is important to note that if Type I zinc is used, it is possible to exceed the permissible exposure limit (PEL) for lead when the products are removed by abrasive blasting. For additional information relating the lead content of the coating to worker exposure to lead during blasting see Gary L. Tinklenberg and Denise M. Doezema, “Health Concerns for Workers Using Zinc-Rich Coatings,” Journal of Protective Coatings and Linings, Vol. 15, No. 5 [May 1998], pp 36-46. In addition to lead, cadmium and other toxic metals may pose a health hazard. Placing overly restrictive requirements on some materials may result in the inability of manufacturers to produce products meeting this specification.
13.5 Coatings that fail the ASTM B 117 test may perform well under actual service conditions. For most coatings, the use of ASTM D 5894 instead of ASTM B 117 has proven to be a more reliable predictor of performance. However, it appears that untopcoated zinc-rich primers may still be reasonably evaluated using ASTM B 117.
13.6 SOURCES FOR OTHER TESTS: Standard tests that may be useful for further qualification are available from a number of organizations, including ASTM, U.S. Government Federal and Military Specifications (TT-P; MIL-P, etc.), Federal Test Method Standards (141), and the  Canadian Government Specifications Board. However, it should be emphasized that a well designed non-standard test may often provide more meaningful information for a given service condition than one or more standard tests. Some supplementary performance tests are described in the Appendix.
13.7 QUALIFIED MARINE EXPOSURE SITES: Amarine site is always in close proximity to the ocean. Other criteria for classifying the environment, such as corrosion rate of bare steel or bare zinc (in accordance with ASTM G 92) or mean annual precipitation and temperature, may also be required when agreed to among contracting parties.

The 25-meter (80-foot) lot at LaQue Corrosion Services, Wrightsville Beach (Kure Beach), NC, has been shown suitable for this specification’s exterior marine exposure. The above test site has an average bare steel corrosion rate of about 100 to 125 micrometers (4 to 5 mils) per year, based on panels exposed for 12 months. Short term corrosion rates derived from panels exposed for one to three months can be as high as 500 to 750 micrometers (20 to 30 mils) per year.

Another suitable location is Ocean City’s Marine Atmospheric Exposure Site. This is located near the town of Sea Isle City, New Jersey. The test site is approximately 30m (100 feet) from the ocean and is bordered on the west by a saltwater bay and marsh land. Mild steel corrodes at 43 micrometers/yr (1.7 mils/year) under natural conditions and 460 micrometers/yr (18.1 mils/year) with sea spray. Zinc corrodes at 2.3 micrometers/yr (0.09 mil/year) under natural conditions.

13.8 INTERIM QUALIFICATION: Level 1 qualification may be used as an interim qualification for a candidate zinc primer. Under this scheme, a procuring agency could accept the primer for use on small structures, partial structure painting, or other limited applications. The interim qualification would be valid for a period of 18 months, at which time the longer test fence exposures (Level 2) would be completed.
13.9 The procurement documents should establish the responsibility for samples, testing, and any required affidavit certifying full compliance with the specification.

13.10 QUALITY ASSURANCE TESTS: If the user chooses, tests may be used to determine the acceptability of a lot or batch of a qualified coating. 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 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 qualifi cation sample. The results of these tests are used to establish pass/fail criteria for quality assur­ance testing of supplied products.
13.10.1 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 interlaboratory precision of the test methods used.

Example: A common quality assurance test is density (weight per gallon) as measured by ASTM D 1475. The interlaboratory 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 user’s 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.

13.10.2 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), color (ASTM D 1535), condition in container (FED­STD-141, Method 3011), and odor (ASTM D 1296).
13.11 Another SSPC specification for zinc-rich coatings is SSPC-Paint 20.

APPENDIX–Supplementary Performance Tests
While not required to meet the requirements of this specifi­cation, the following or other performance tests may be valuable to the purchaser because of the diversity of possible service environments in which these primers may be used. Agreement between contracting parties as to these tests and results must be established before issuing procurement documents.
A.1 BULLET HOLE TEST
A.1.1Significance of Test: This test is intended to evaluate the ability of a primer to sacrifice itself and cathodically protect adjacent areas of bare steel.
A.1.2 Description of Test: Test panels shall be triplicate flat mild steel plates, 75 x 150 x 1.6 mm (3 x 6 x 1/16 inches), blast cleaned to SSPC-SP 5. A magnet, tape, or other suitable method is to be used to mask a 3.8 cm (1.5 inch) diameter circle in the center of the panel. Coating shall be applied according to the manufacturer’s specifications, including recommended dry film thickness. If masking tape is used, any residue remaining after the tape is removed must be cleaned from the panel with mineral spirits or other suitable methods that will not damage the test coating. The back of the panel is to be painted with vinyl (e.g., SSPC-Paint 9) or other resistant paint. Edges of the panel are to be dipped in the vinyl paint or protected from corrosion by another suitable method. Once the zinc dust primer is hardened for a minimum of two weeks, the panels are placed in a one-liter (one-quart) jar, which is filled with a 5% sodium chloride solution. The water is changed weekly.
A.1.3 Rating and Evaluation Criteria: The time at which visible rust first appears anywhere on the panel is recorded. A coating will have passed the bullet hole test if none of the replicate panels exhibits visible rust within 21 days for an inorganic zinc primer or within 14 days for an organic zinc primer.
A.1.4 Additional Notes: Experimental results on bullet hole testing of various zinc-rich coatings are given in SSPC Report 87-02, “Level of Zinc Required in Zinc-Rich Paints.” A similar bullet hole immersion test is described in AASHTO M300.
A.2 FUEL AND SALT WATER IMMERSION
A.2.1 Significance of Test: Inorganic zinc-rich coatings have been used in ballast tanks, which are alternately exposed to petroleum fuel and seawater ballast.
A.2.2 Description of Test: A test developed by the U.S. Navy calls for immersion of two blast cleaned and coated panels in the following cycle: one week in 3% salt water; one week in aromatic synthetic gasoline; and two hours in hot (80°C, 176°F) synthetic sea water (to simulate cleaning conditions). Details for making synthetic sea water are furnished in ASTM D 1141.
A.2.3 Evaluation Criteria: After 20 cycles, coatings are required to exhibit no pinpoint rusting, no loss of adhesion, no blisters larger than 1.5 millimeters (1/16 inch) in diameter, and no more than 3% of the surface covered with rust and/or blisters.
A.3 ACCELERATED WEATHERING
A.3.1 Significance of Test: This test is primarily intended to determine the effect of ultraviolet radiation on degradation of the binder. Accordingly, it is most appropriate for organic-type binders or topcoated systems.
A.3.2 Description of Test: While two methods are described, the exact method should be agreed to by the contracting parties. Suitably sized panels shall be prepared in accordance with Sections 5.1 through 5.4 and 5.6 and tested in a xenon arc light exposure apparatus (ASTM G 155) or in a fluorescent UV condensation type apparatus (ASTM G 154, four-hour/four-hour UV/condensation cycle, using UV B bulbs). Testing should be done in triplicate for 1,000 to 2,000 hours.
A.3.3 Evaluation Criteria: All primers should be evaluated for rust formation, while organic primers should also be evalu­ated for UV degradation problems. Criteria for rejection should be mutually agreed upon among the contracting parties.

PAINT SPECIFICATION NO. 29 – Zinc Dust Sacrificial Primer, Performance-Based