State of California
AIR RESOURCES BOARD

Staff Report for the Proposed 
Suggested Control Measure
for Architectural Coatings

Volume II:
Technical Support Document

VI.

DESCRIPTION AND TECHNICAL ASSESSMENT
OF THE COATING CATEGORIES

TABLE OF CONTENTS FOR CHAPTER VI - SECTION B and SECTION C

For SECTION A CLICK HERE

B. COATING CATEGORIES FOR WHICH THE PROPOSED VOC LIMITS ARE GENERALLY CONSISTENT WITH DISTRICT RULES

We are proposing VOC limits for the following 16 coating categories that are generally consistent with the VOC limits in California's district architectural coatings rules, including the South Coast AQMD's Rule 1113. The discussions for each of these coating categories includes:

1. product category description;
2. discussion of the proposed volatile organic compound (VOC) limit, and our rationale for the proposed limit; and
3. if applicable, a discussion of the issues associated with the proposed VOC limit, as raised by industry. The product categories are listed in alphabetical order.

1. Bond Breakers

Product Category Description:

Bond breakers are coatings that are applied between layers of concrete to prevent bonding of the first layer to the second layer. Coatings in this category are similar to form release compounds, except that form release compounds prevent bonding of the concrete to a
non-concrete form (TRG/ARB, 1989). The first coat of a bond breaker also helps cure the concrete (U.S. EPA, 1998).

Table VI-44 below summarizes our estimate of the sales and VOC emissions from the bond breakers category.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
** Grams VOC per liter of coating, less water and exempt compounds.
PD = Protected Data.

Proposed VOC Limit and Basis for Recommendation:

We are proposing a 350 g/l VOC limit for bond breakers effective January 1, 2003. This proposed VOC limit is technologically and commercially feasible based on: the high complying marketshare; the limit in current district rules; and the fact that most district architectural coating rules have had the same limit for several years. We also note that no adverse comments were received about the proposed limit.

Districts that regulate bond breakers (all districts except the Bay Area, Butte, Colusa, Feather River, and Monterey districts where the category is exempt) have a VOC limit of 350 g/l. Based on the recommendation of the 1989 SCM, the VOC limit for bond breakers of 350 g/l went into effect in district rules in September 1990 (TRG/ARB, 1989).

The U.S. EPA's National Architectural Coatings Rule limit of 600 g/l. However, this limit is found in the upper range of VOC content limits in existing state rules (none of the rules has a limit higher than 600 g/l) (U.S. EPA, 1998). We recommend that the VOC limit for bond breakers remain at 350 g/l at this time, which is consistent with current district rules.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
PD =Protected Data.

Issues:

1. Issue: No comments were received on bond breakers, and we know of no unresolved issues with this category.

2. Concrete Curing Compounds

Product Category Description:

Concrete curing compounds are coatings that are applied to fresh concrete to retard moisture evaporation. These coatings are used in road construction to provide moisture retention during curing, to help with design strength and other properties. Concrete curing compounds are designed to meet a number of ASTM specifications, including ASTM C-309, Type 1, 1D, and 2; Class A (U.S. EPA, 1998).

The U.S. EPA determined that concrete curing compounds, as well as other concrete curing products, may be underrepresented in the national Architectural Coatings Survey. One commenter explained that this is because concrete curing products are made by the construction industry, not coating manufacturers (U.S. EPA, 1998). They may also be underrepresented in the ARB's 1998 Architectural Coatings Survey for the same reason.

Table VI-46 below summarizes our estimate of the sales and VOC emissions from the concrete curing compounds category.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
** Grams VOC per liter of coating, less water and exempt compounds.

Proposed VOC Limit and Basis for Recommendation:

We are proposing a 350 g/l VOC limit for concrete curing compounds effective January 1, 2003. This proposed VOC limit is technologically and commercially feasible based on: the high complying marketshare; the limit in current district rules and the National Rule; and the fact that most district architectural coating rules have had the same limit for several years. We also note that no adverse comments were received about the proposed limit.

All district rules except one have a VOC limit of 350 g/l for concrete curing compounds (Butte County has a VOC limit of 800 g/l). In addition to the California districts, Arizona, Massachusetts, New Jersey, and New York have a 350 g/l limit (U.S. EPA, 1998). The U.S. EPA's National Architectural Coatings Rule also has a VOC limit of 350 g/l. All but one commenter argued that the limit is achievable (U.S. EPA, 1998).

We recommend that the VOC limit remain at 350 g/l at this time, the same as in current district rules, state rules, and the National Rule. The survey shows that there is about 95 percent compliance at 350 g/l, and this category is already heavily dominated by water-based formulations.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).

Issues:

1. Issue: No comments were received on concrete curing compounds, and we are unaware of any unresolved issues.

3. Dry Fog Coatings

Product Category Description:

Dry fog coatings, also called dry fall coatings or mill white coatings, are formulated so that when sprayed onto a substrate, the overspray droplets dry before they contact the floor or other surfaces. The coatings are designed to dry after falling 8 to 10 feet, depending on the formulation and the weather conditions. The use of dry fog coatings minimizes the amount of masking and covering of surfaces that are not to be coated, and the dried coating can simply be swept up for easy cleanup. The definition clarifies that these coatings are to be applied by spraying, not by brush or roller, since the quick-drying characteristics of dry fog coatings would not be necessary with non-spray application techniques (TRG/ARB, 1989).

Table VI-48 below summarizes our estimate of the sales and VOC emissions from the dry fog coatings category. As shown, dry fog coatings are available as both water-based and solvent-based products, with the lower VOC water-based products accounting for the majority of sales.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).

** Grams VOC per liter of coating, less water and exempt compounds.

Proposed VOC Limit and Basis for Recommendation:

We are proposing a 400 g/l VOC limit for dry fog coatings effective January 1, 2003. This proposed VOC limit is technologically and commercially feasible based on: the high complying marketshare; the limit in current district rules and the National Rule; the fact that most district architectural coating rules have had the same limit for several years; and a review of product literature on coatings included in this category. We also note that no adverse comments were received about the proposed limit.

The VOC limit of 400 g/l for dry fog coatings is found in the all district rules (except Bay Area, Butte, Colusa, Feather River, and Monterey, where the category is exempt). The U.S. EPA's National Architectural Coatings Rule also specifies a VOC limit of 400 g/l. National survey data showed that 84 percent of dry fog coatings sales were at or below 400 g/l. Arizona, Kentucky, New York, New Jersey, Massachusetts, Rhode Island, and the California districts have the same limit. The U.S. EPA concluded that the evidence shows that dry fog coatings at or below 400 g/l perform acceptably well (U.S. EPA, 1998).

We recommend that the VOC limit for dry fog coatings remain at 400 g/l at this time, the same as in current district rules, state rules, and the National Rule. There is almost 97 percent compliance at 400 g/l.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).

Issues:

1. Issue: No comments were received on dry fog coatings and, to our knowledge, no unresolved issues remain.

4. Fire-Retardant Coatings - Clear

Product Category Description:

Fire-retardant coatings are used to bring building and construction materials into compliance with federal, State and local building code requirements. The coatings must be fire tested and rated for their ability to retard ignition and flame spread. Both the coatings and the testing agency must be approved by building code officials. Clear fire-retardant coatings include, but are not limited to, clear varnishes and sealers. Fire-retardant coatings used on wood shingles are pressure-applied into the wood in a factory (Ho, 1999), and therefore, are not subject to the architectural coating rule.

Most fire-retardant coatings work by suppressing flame through intumescence, which means they become plastic and puff up on exposure to flame or excessive heat, solidifying into a foam about fifty times as thick as the coating film. This foam insulates the substrate from the flame (LeSota, 1995).

Fire-retardant coatings reduce flame spread on the surface of a material. Fire-retardant coatings are tested in a fire test chamber using ASTM Method E 84, "Standard Test Method for Surface Burning Characteristics of Building Materials." ASTM Method E 84 is used for testing of interior building materials, not those used on the exterior of buildings (Ho, 1999). This method requires that a 25 foot panel of the substrate coated with the fire-retardant coating be exposed to flame for ten minutes. The retarding of flame spread and smoke development are measured, and the coating receives a flame spread rating equating to Class A, B, or C building materials (Bratcher and Alvarez, 1996).

California building codes specify three classes of building materials (which correspond to the Class A, B, and C materials mentioned above), each with a range of possible flame spread indices. The following table summarizes this information (California Building Code, 1998).

The definition used in the SCM is essentially the National Rule definition, except that we have removed the language pertaining to fire-resistant. During our research on the fire-retardant category, we found that a separate category for fire-resistant coatings was needed because these two categories are quite different in the mode of action, the materials protected, and the test methods used.

The fire-retardant coatings definition in the SCM also differs significantly from the definition used in district rules and the 1989 SCM. These district definitions describe fire-retardant coatings as those that have a flame spread index of less than 25 when tested in accordance with ASTM Designation E 84-87, using Douglas fir as the substrate. This definition is limiting in several ways.

The definition used in district rules specifies a flame spread index of less than 25, but as seen in the table above, this limits the classification of the building materials to Class I (Class A in the NFPA classification). The California Building Code allows Class II and III materials (Class B and C in the NFPA classification) to be used in some applications, for example where the materials are protected on both sides by sprinkler systems (California Building Code, 1998).

The districts' rule definition restricts the flame spread testing to Douglas fir. This is limiting because it precludes testing and certification of fire-retardant coatings on other building materials such as acoustical tiles, drywall, plywood, etc. Manufacturers of fire-retardant coatings are required to test and register their products with the State Fire Marshal's Office, and testing must be on the variety of substrates that the manufacturer claims the coating can be used on, not just Douglas fir (Woods, 1999).

The coatings are tested by a variety of testing laboratories. Each building inspection agency has its own list of approved laboratories for each type of building material
(Woods, 1999). In California, most building code officials at the local level use the approved testing laboratories list of the State Fire Marshal (Ho, 1999). These laboratories are further subdivided into those who are qualified and equipped to conduct certain tests and examinations (State Fire Marshal, 1998). The proposed definition does not restrict the choice of testing agencies to a single laboratory such as Underwriters Laboratory. The term ?approved laboratory" is used in the industry to imply a lab acceptable to a code official (Hopper, 1999). The term "testing agency" was chosen for the proposed definition based on the terminology used in the California Building Code.

Manufacturers submit their coatings for testing on certain specified building materials to the testing laboratory. The laboratory determines the flame spread and smoke density ratings. The test results are then submitted to the State Fire Marshal for review. If approved, the State Fire Marshal lists the product in its listing service or registry. The manufacturer must pay a fee to register the product in the listing service, and the listing has an expiration date. Both the fire-retardant chemical and the fire-retardant coating must be registered by the State Fire Marshal (Ho, 1999). Architects, contractors, and others who use these coatings have access to the listing of approved coatings.

The reference to federal building codes in the proposed definition is included because federal facilities such as office buildings, courthouses, prisons, hospitals, and military bases are subject to the federal requirements in the NFPA codes, whereas the California requirements are based on the ICBO codes (Woods, 1999).

The test method is important in defining fire-retardant products. The test method for flame spread index is referenced in the Test Methods section of the rule for information purposes. ASTM Designation E-84 is referenced, but the California Building Code references UBC Standard 8-1, which is virtually identical to the ASTM method. Individual testing laboratories also have their own flame spread tests; for example, Underwriters Laboratories uses UL 723, which is virtually the same as ASTM Method E-84 (Hopper, 1999).

Table VI-50 below summarizes our estimate of sales and VOC emissions from the clear fire-retardant coatings category.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).

** Grams VOC per liter of coating, less water and exempt compounds.
PD = Protected data.

Proposed VOC Limit and Basis for Recommendation:

We are proposing a 650 g/l VOC limit for clear fire-retardant coatings effective January 1, 2003. This proposed VOC limit is technologically and commercially feasible based on: the high complying marketshare; the limit in current district rules; the fact that most district architectural coating rules have had the same limit for several years; a review of product literature on coatings included in this category; and discussions with manufacturers. We also note that no adverse comments were received about the proposed limit.

The VOC limit of 650 g/l for clear fire-retardant coatings is found in all district rules (except Bay Area, Butte County, Colusa County, and Feather River, which exempt this category, and Monterey and Placer County, which do not have a category for fire-retardant coatings).

The National Rule VOC limit for clear fire-retardant/resistive coatings is 850 g/l. However, the U.S. EPA does not provide rationale for this VOC limit (U.S. EPA, 1998). We recommend that the VOC limit for clear fire-retardant coatings remain at 650 g/l at this time, the same as in the 1989 SCM and all current district rules. There is 100 percent compliance at this limit.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
PD = Protected Data.

Issues:

1. Issue: No unresolved issues remain with this category.

5. Fire-Retardant Coatings - Opaque

Product Category Description:

Fire-retardant coatings are described in the previous section on clear fire-retardant coatings. Opaque fire-retardant materials include, but are not limited to, coatings with flat or non-flat finishes and primers.

Table VI-52 below summarizes our estimate of sales and VOC emissions from the opaque fire- retardant coatings category. As shown, both solvent-based and water-based products are available, with the lower VOC water-based products accounting for the majority of sales.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
** Grams VOC per liter of coating, less water and exempt compounds.

Proposed VOC Limit and Basis for Recommendation:

We are proposing a 350 g/l VOC limit for opaque fire-retardant coatings effective January 1, 2003. This proposed VOC limit is technologically and commercially feasible based on: the high complying marketshare; the limit in current district rules; the fact that most district architectural coating rules have had the same limit for several years; a review of product literature on coatings included in this category; and discussions with manufacturers. We also note that no adverse comments were received about the proposed limit.

The VOC limit of 350 g/l for opaque fire-retardant coatings is found in all district rules (except Bay Area, Butte County, Colusa County, and Feather River, which exempt this category, and Monterey and Placer County, which do not have a category for fire-retardant coatings).

The National Rule VOC limit for opaque fire-retardant/resistive coatings is 450 g/l. However, the U.S. EPA does not provide a rationale for this VOC limit (U.S. EPA, 1998). We recommend that the VOC limit for opaque fire-retardant coatings remain at 350 g/l at this time, the same as in the 1989 SCM and all district rules. There is virtually 100 percent compliance at this limit.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).

Issues:

1. Issue: No unresolved issues remain on this category.

6. Form Release Compounds

Product Category Description:

Form release compounds are products designed for use on concrete forms to prevent freshly poured concrete from sticking to the form. The forms may be wood, metal, or other material other than concrete. They are used extensively in the building industry in concrete pouring operations (TRG/ARB, 1989).

A commenter on the National Rule speculated that concrete form release compounds may be underrepresented in the national Architectural Coatings Survey because they are made by the construction industry, not coating manufacturers (U.S. EPA, 1998). They may also be underrepresented in the ARB's 1998 Architectural Coatings Survey for the same reason.

Table VI-54 below summarizes our estimate of sales and VOC emissions from the form release compounds category. Sales were only 10,000 gallons in the 1993 survey, compared to 80,000 gallons in the 1998 survey.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
** Grams VOC per liter of coating, less water and exempt compounds.

Proposed VOC Limit and Basis for Recommendation:

We are proposing a 250 g/l VOC limit for form release compounds effective January 1, 2003. This proposed VOC limit is technologically and commercially feasible based on: the high complying marketshare; the limit in current district rules; and the fact that most district architectural coating rules have had the same limit for several years. We also note that no adverse comments were received about the proposed limit.

The form release compounds category appears in a few district rules: El Dorado, Imperial, Kern, Placer, Sacramento, San Diego, San Joaquin, Santa Barbara, and Ventura, all with a 250 g/l VOC limit. The category falls under the default limit of 250 g/l in the remaining districts.

In the 1989 SCM, the form release compounds category was created to separate these coatings (at a VOC limit of 250 g/l) from bond breakers (at 750 g/l effective September 1989, lowering to 350 g/l in September 1990). At that time, it was estimated that form release compounds were used in larger quantities than bond breakers (TRG/ARB, 1989).

The VOC limit for form release compounds in the U.S. EPA's National Architectural Coatings Rule is 450 g/l. The National Rule limit is found in the upper range of VOC content limits in existing state rules (U.S. EPA, 1998).

We recommend that the VOC limit for form-release compounds remain at 250 g/l at this time, the same as in current district rules.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
PD = Protected Data.

Issues:

1. Issue: No comments were received on form release compounds, and we are unaware of any remaining issues.

7. Graphic Arts Coatings

Product Category Description:

Graphic arts coatings or sign coatings are products designed for hand-application by artists using brushes or rollers. They are used on indoor or outdoor signs or murals and include lettering enamels, poster colors, copy blockers, and bulletin enamels. A coating used on the structural components of billboards is not included in the definition. Most billboard signs are now pre-printed and are pasted to the billboard on-site.

The 1989 SCM clarified which graphic arts coatings were subject to architectural coating rules. This was necessary because, depending on the district in which the coating is applied, what substrate is being used, and where they are applied, graphic arts coatings could be subject to metal parts and products, wood products, plastic parts and products, or architectural coatings rules. The definition was designed to address the needs of sign painters without allowing high VOC coatings to be used for jobs not legitimately requiring sign coatings. To be an architectural coating, the sign would have to be coated after installation (TRG/ARB, 1989). Similarly, U.S. EPA clarified that if the coating is applied to an erected billboard, the coating used on the sign portion of the billboard would be classified as graphic arts, while the coating used on the steel supporting beams of the billboard would be an industrial maintenance coating
(U.S. EPA, 1998).

Table VI-56 below summarizes our estimate of sales and VOC emissions from the graphic arts coating category.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
** Grams VOC per liter of coating, less water and exempt compounds.
*** Includes 100 percent solid coatings.
PD = Protected Data.

Proposed VOC Limit and Basis for Recommendation:

We are proposing a 500 g/l VOC limit for graphic arts coatings effective January 1, 2003. This proposed VOC limit is technologically and commercially feasible based on: the high complying marketshare; the limit in current district rules; and the fact that most district architectural coating rules have had the same limit for several years. We also note that no adverse comments were received about the proposed limit.

All districts that have a graphic arts category in their architectural coating rules have a 500 g/l VOC limit. This category is exempt in the Bay Area, Butte County, Colusa County, Feather River, and Monterey districts. The VOC limit in the U.S. EPA's National Architectural Coatings Rule is 500 g/l. National survey data showed that 96 percent of the coatings were
500 g/l or below. Massachusetts, New York, New Jersey, and Rhode Island are at 450 g/l, while Kentucky and the California districts are at 500 g/l (U.S. EPA, 1998)

In earlier versions of the SCM, we proposed lowering the VOC limit for graphic arts coatings to 150 g/l, based on survey data. There is a large waterborne or 100 percent solids component of the survey data that may be non-architectural or may represent sign coatings other than those included in the definition. Based on comments and minimal emission reductions, we changed the proposed VOC limit to match that of district rules and the National Rule.

We recommend that the VOC limit for graphic arts coatings remain at 500 g/l at this time, the same as in current district rules and the National Rule. There is 81 percent compliance at the proposed 500 g/l limit.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).

Issues:

1. Issue: There are no known unresolved issues with this category.

8. Magnesite Cement Coatings

Product Category Description:

Magnesite cement coatings are designed for use on magnesite cement decking to protect the magnesite cement substrate from erosion by water.

Magnesite is a naturally occurring mineral composed of magnesium carbonate. For decades, exterior and interior floors have been made from magnesite because it is lightweight, stronger than concrete, water-resistant, non-combustible, and long-lasting (Magnesite, undated). Since the 1970s, newer materials have replaced magnesite cement in new construction. However, there is still a demand for magnesite cement for repair and retrofit of old magnesite cement (Armstrong, 1999).

Magnesite floors are laid using a formulation containing magnesium oxychloride cement and inert fillers. Clear and pigmented sealers are used to protect these magnesite floors, decks, and stairs from the weather, and to cover older surfaces that are discolored, patched, or worn (Magnesite Flooring System, undated). Magnesium oxychloride is highly alkaline and prevents adhesion of most coatings applied to it. The only successful magnesite cement coatings are acrylic lacquers. Coatings other than acrylic lacquers have failed within a week due to delamination (TRG/ARB, 1989).

Table VI-58 below summarizes our estimate of sales and VOC emissions from the magnesite cement coatings category.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
** Grams VOC per liter of coating, less water and exempt compounds.
PD = Protected Data.

Proposed VOC Limit and Basis for Recommendation:

We are proposing a 450 g/l VOC limit for magnesite cement coatings effective January 1, 2003. This proposed VOC limit is technologically and commercially feasible based on: the limit in current district rules; and the fact that most district architectural coating rules have had the same limit for several years: discussions with a major manufacturer who has recently developed a complying product; and a technology assessment performed by the South Coast AQMD in 1996. We also note that no adverse comments were received about the proposed limit.

The VOC limit for magnesite cement coatings in most district rules is 450 g/l. The Mojave Desert and San Diego districts have a VOC limit of 600 g/l, and several districts do not list this category in their table of standards. The VOC limit in the U.S. EPA's National Architectural Coatings Rule is 600 g/l.

The South Coast AQMD examined magnesite coatings in its 1996 amendments to Rule 1113. At that time, an interim VOC limit of 600 g/l was established, and as of January 1, 1999, a VOC limit of 450 g/l is now in effect (South Coast AQMD, 1996). In November 1998, a major manufacturer indicated that after many years of reformulation, they could meet the 450 g/l limit. There are some limitations in using the coating in hot weather, however, which are handled by applying the coating at night (Armstrong, 1999).

We recommend that the VOC limit for magnesite cement coatings remain at 450 g/l at this time, the same as in current district rules.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
PD = Protected Data.

Issues:

1. Issue: No comments were received regarding magnesite cement coatings, and to our knowledge there are no unresolved issues.

9. Mastic Texture Coatings

Product Category Description:

Mastic texture coatings are products used to cover and conceal holes, cracks, and surface irregularities. These coatings are applied in a single coat, with the dry film at least 10 mils thick.
These coatings are highly viscous water-based or solvent-borne coatings used by homeowners or contractors for interior and exterior masonry (U.S. EPA, 1998). The definition in the 1989 SCM includes a film thickness specification to identify that these coatings are high-build coatings (TRG/ARB, 1989).

Table VI-60 below summarizes our estimate of sales and VOC emissions from the mastic texture coatings category.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
** Grams VOC per liter of coating, less water and exempt compounds.
PD = Protected Data.

Proposed VOC Limit and Basis for Recommendation:

We are proposing a 300 g/l VOC limit for mastic texture coatings effective January 1, 2003. This proposed VOC limit is technologically and commercially feasible based on: the high complying marketshare; the limit in current district rules; the fact that most district architectural coating rules have had the same limit for several years; a review of product literature on coatings included in this category; and comments justifying this limit based on performance requirements. We also note that no adverse comments were received about the proposed limit.

All district rules that include a category for mastic texture coatings have a VOC limit of 300 g/l. This category is exempt in the Bay Area, Butte County, Colusa County, Feather River, and Monterey districts. The VOC limit in the U.S. EPA's National Architectural Coatings Rule is also 300 g/l.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).

Issues:

1. Issue: There are no known unresolved issues with this category.

10. Metallic Pigmented Coatings

Product Category Description:

Metallic pigmented coatings are products that contain at least 48 grams of elemental metal pigment per liter of coating, as applied. This metal content is equivalent to 0.4 pounds of metal per gallon of coating. South Coast AQMD Method 318-95, "Determination of Weight Percent Elemental Metal in Coatings by X-Ray Diffraction," is used to determine the metallic content of the coating.

Metallic pigmented coatings produce a dry film that has a metallic appearance. This effect is produced by incorporating fine flakes of various metals (e.g., copper, bronze, aluminum) to the coating. The aluminum can be leafing or nonleafing. Leafing means that the metal is in the form of thin flat flakes that align themselves so that they appear to be floating on or near the surface of the coating (LeSota, 1995).

In the U.S. EPA rulemaking, issues were raised about the inclusion of zinc-rich coatings in the metallic pigmented coating category. Zinc-rich coatings are applied to structural steel beams to prevent corrosion during the construction of large buildings. Zinc-rich coatings are lower in VOC than metallic pigmented coatings because the zinc content of the dry film can be 50 percent or higher. U.S. EPA concluded that creating a separate category for zinc-rich coatings was not warranted, and these coatings fit under the metallic pigmented category (U.S. EPA, 1998).

Inorganic zinc-rich primers are considered metallic pigmented coatings because the elemental zinc particles in the film are held to the surface of the substrate through a non-organic silicate binder (LeSota, 1995). Organic zinc-rich primers are also considered metallic pigmented coatings because elemental zinc powder is used, along with an organic binder such as an epoxy or urethane that holds the pigment to the film (Sherwin-Williams, undated). The pigment zinc oxide (ZnO) does not contain elemental zinc (LeSota, 1995) and thus does not qualify as a source of zinc for metallic pigmented coatings. Aluminum roof coatings are considered metallic pigmented coatings, as are asphalt aluminum roof coatings as long as they have 48 grams of elemental metal pigment per liter of coating, as applied. Bituminous coatings are excluded from the metallic pigmented coating definition in the National Rule, but they have the same VOC limit of 500 g/l.

Table VI-62 below summarizes our estimate of sales and VOC emissions from the metallic pigmented coatings category.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).
** Grams VOC per liter of coating, less water and exempt compounds.

Proposed VOC Limit and Basis for Recommendation:

We are proposing a 500 g/l VOC limit for metallic pigmented coatings effective January 1, 2003. This proposed VOC limit is technologically and commercially feasible based on: the high complying marketshare; the limit in current district rules and the National Rule; the fact that most district architectural coating rules have had the same limit for several years; and a review of product literature on coatings included in this category. We also note that no adverse comments were received about the proposed limit.

Every district rule with a metallic pigmented category has a VOC limit of 500 g/l. This category is exempt in the Bay Area, Butte County, Colusa County, Feather River, and Monterey districts. The National Rule VOC limit is also 500 g/l, and includes coatings formulated with zinc pigment. Kentucky, New York, New Jersey, Massachusetts, Rhode Island, and some of the California districts have 500 g/l limits. The national survey showed that 90 percent of these coatings had VOC contents from 300-500 g/l (U.S. EPA, 1998).

In earlier versions of the SCM, we had proposed excluding zinc from the definition of metallic pigmented coatings because zinc-rich primers, which would fall under this category, have a VOC content limit lower than 500 g/l. We are now proposing that the definition include coatings containing elemental zinc, which is consistent with the National Rule and South Coast AQMD Rule 1113. Further, we have proposed that the most restrictive VOC limit section of the SCM does not apply to metallic pigmented coatings, as has been the case for years in most district rules. Thus, a coating containing the metallic content required by the definition need meet only the 500 g/l VOC limit of metallic pigmented coatings, even though it overlaps with another category.

We recommend that the VOC limit for metallic pigmented coatings remain at 500 g/l at this time, the same as in current district rules and the National Rule. The survey shows 98 percent compliance at this limit, even with solvent-based coatings.

* Based on ARB's 1998 Architectural Coatings Survey Results Final Report (ARB, 1999).

Issues:

1. Issue: The proposed definition restricts this category to metallic coatings not including zinc metallic coatings. With the introduction of the lower limits, this limitation is unreasonable, and the zinc exclusion should be removed.

Response: We agree, and have removed the exclusion of zinc from the definition.


2. Issue: We manufacture a zinc-rich coating containing zinc powder that contains 95 percent zinc in the dried film and is applied in the field. Zinc is the densest and most difficult metal to

formulate into coatings. We urge you to change your definition to include zinc.

Response: We agree with the change in the definition. The coating described would be considered a metallic pigmented coating.


3. Issue: The higher limit for the asphaltic aluminum coating is appropriate because they are the best product for increasing reflectance on black asphaltic roofing surfaces.

Response: The National Rule definition for metallic pigmented excludes bituminous coatings, but we have not proposed similar language, in keeping with the long-standing definition used in California. We agree that this asphaltic aluminum roof coating would be considered a metallic pigmented coating.


4. Issue: The definition for metallic pigmented coatings exempts zinc as a metal, which would essentially eliminate organic and inorganic zinc-rich primers. We request that you change this definition to agree with South Coast AQMD Rule 1113 and the National AIM Rule definitions.

Response: We agree with the change in the definition to include elemental zinc metal. We also agree that organic and inorganic zinc-rich primers are included in the definition of metallic pigmented coating.


5. Issue: The proposed definition for metallic pigmented coatings excludes zinc. This is surprising since virtually all other regulatory bodies have included zinc. Zinc-rich coatings at 250 g/l have not been proven for field application. Water-based inorganic zinc (which has close to zero VOC) is considered by a majority of applicators and specifiers to be unsuited for field application.

Response: We modified the definition to include zinc-rich coatings as suggested.


6. Issue: High-temperature metallic coatings shouldn't be penalized because they can be used at high temperature. The use of metallic pigments requires a higher limit because of the metal. The metallic pigmented definition excludes zinc, while the South Coast AQMD and National Rule include zinc.

Response: We have made the requested change to the definition of metallic pigmented coatings. The exception under the Most Restrictive VOC Limit section in the SCM specifies that high-temperature metallic pigmented coatings are subject to the VOC limit for metallic pigmented coatings at 500 g/l.


7. Issue: There are a lot of metallic coatings that contain powdered zinc, copper, bronzes based on zinc, and combinations of copper/aluminum/zinc pigments. Pigment is defined in the National Rule to include corrosion inhibition, but pigment is not defined in the SCM. Zinc-rich primers have VOC contents of roughly 340-420 g/l. Zinc-rich primers should be in their own category or in the metallic pigmented category.

Response: The definition of pigment in the National Rule refers to finely ground, insoluble powder that is used for color,