Specialty Minerals Products for Paint and Coatings

Our lives are touched daily by countless products made with some kind of paint or coating. These products are on the walls of our houses, on the surfaces of appliances and furniture, on our children’s bikes and wagons, on the cars we drive to work, the bridges we drive over, the ships that may have brought us those cars in the first place, on the file cabinets in our offices, and on machinery and storage tanks in our factories.

Specialty Minerals Inc.’s (SMI’s) filler and extender pigments help make these coatings bright, functional, and durable.

Using Specialty Minerals Products in Paints and Coatings
Many types of coatings benefit from using a SMI mineral filler and extender in its formulation—architectural or decorative, industrial, and the range of specialty coatings as follows:

  • Architectural / Decorative Coatings – interior, exterior and wood stains.

  • Industrial Coatings including automotive OEM and powder coatings.

  • Specialty Coatings including maintenance, marine, traffic or road marking, automobile refinishing, and aerosol paints.

Specialty Minerals Minerals for Paints
SMI manufactures ground calcium carbonates (GCCs, also called ground limestones), talcs and precipitated calcium carbonates (PCCs) in its U.S., U.K. and Brazil plants for use in coatings as follows:

  • Ground calcium carbonates in coatings

  • Precipitated calcium carbonates in coatings

  • Talcs in coatings

Specialty Minerals Products for Architectural Coatings

Architectural coatings are used on the interior and exterior of structures such as houses, apartments and office buildings. Other terms for architectural coatings are trade-sales paints, decorative coatings, building paints, and DIY (do it yourself) paints. Included are the semi-transparent and opaque stains for wood. These are the coatings people most commonly see, use, and apply.


To satisfy the decorative and functional needs of their users, paints for home and commercial construction are formulated in a wide range of appearances, from flat or matte to shiny high-gloss with ranges of eggshell and semi-gloss in between. Exterior architectural coatings and wood stains must be formulated to withstand the rigors of wind, rain, and direct sunlight. Interior paints are generally used in a more benign environment, but one where surface flaws are more readily noticed, and where touch-up and washability are important.

The color of the coating is determined by the prime pigment used. This will usually be titanium dioxide (TiO2), if the paint is white or light-colored; in darker paint shades, it may be iron oxide, carbon black or some brightly colored organic pigment.

Extender and Filler Minerals in Architectural Paints
In addition to the prime color pigments described above, decorative coatings and stains also contain filler or extender pigments, such as ground calcium carbonate (GCC), talc and kaolin. The key function of these minerals is to lower costs by either extending or maximizing the efficiency of the more costly color pigments, reducing the amounts needed to achieve the desired color, and filling up the volume in the paint, thus reducing the use of resins and/or solvents.

In choosing a filler pigment, both the demands of the end use and the cost constraints (i.e. selling price) must be considered. The performance of a given filler in a coating depends on its basic chemical nature, as well as its particle size, particle shape, surface chemistry, color, and whiteness or brightness (both dry and wet).  Most decorative coatings contain a combination of filler minerals of different types and sizes to achieve the targeted balance of application, appearance, durability, and cost properties.

Ground calcium carbonates, also called ground limestones, are generally the most economical and are very bright. However, they do not contribute much to film integrity and their chemistry makes them subject to acid attack. The synthetic form of calcium carbonate, precipitated calcium carbonate (PCC), is widely used in some areas of the world, especially in latex or emulsion paints.

Talc improves moisture barrier properties of exterior paints and semi-transparent or opaque stains due to its platy particle shape and hydrophobic nature. It is not as bright as the best calcium carbonates and is higher in cost. Talc is also used in predispersed liquid colorants for point-of-purchase paint-tinting systems where it aids suspension and color development of the prime color pigments in the colorant.


Specialty Minerals Filler and Extender Pigments for Architectural Coatings
In the U.S. Specialty Minerals Inc. (SMI) manufactures a variety of filler pigments used in trade sales paints. These include:

  • Vicron® - East and Vicron® – West GCCs – high-brightness fillers, from 3 to 13 microns,  from SMI mines and plants in Adams, Massachusetts and Lucerne Valley, California.

  • Marblewhite® - East and Marblewhite West GCCs – 125, 200 and 325 mesh bright limestones, also manufactured in Adams, Massachusetts and Lucerne Valley, California.

  • Talcron® talcs – 1 to 8 micron bright paint talcs, mined and manufactured in Barretts, Montana.

Grades of PCCs for paint include:

  • Calopake F PCC.pdf – 2 micron clustered scalenohedral calcite PCC for exceptional brightness and titanium dioxide extension. Manufactured in SMI’s Birmingham, U.K. facility.

  • Sturcal F PCC.pdf – 2.8 micron acicular aragonite, also produced in Birmingham.

Specialty Minerals Products for Industrial Coatings

“Industrial coatings” generally refers to paints that are factory applied to manufactured goods as part of the production process. Such paints are also known as original equipment manufacture (OEM) coatings or product finishes. Examples are the coatings used on automobiles, appliances, farm implements, furniture, and metal building products. These coatings tend to be applied in controlled environments, using strict quality control procedures.

Minerals in Industrial Coatings
Unlike architectural coatings, industrial coatings will incorporate extender pigments for additional reasons besides mere cost reduction. These formulations lean towards minerals that add some functionality or performance to the coating.

When an OEM formulation includes an extender, a talc will generally be chosen. Talc is used in product primers because it adds easy sandability and good adhesion. Talc can also be used in implement finishes where it helps to form a moisture barrier, and improves exterior durability.

In general, calcium carbonate materials are not used in industrial finishes with the exception of nano-type precipitated calcium carbonates (PCC) which may be used for titanium dioxide (TiO2) extension. Both uncoated and coated nano PCCs are used, but the choice depends on the system.

Specialty Minerals Minerals for Industrial Coatings

Specialty Minerals Inc. (SMI) manufactures high-quality talc fillers for industrial coating in the U.S. and nano PCCs, uncoated and coated, in the U.S. and U.K.

Specialty Minerals Precipitated Calcium Carbonates for Paint and Coatings

Precipitated calcium carbonate (PCC) is most commonly used in paint as an extender for titanium dioxide, or TiO2. The small and narrowly distributed PCC particles help space the individual TiO2 particles and maximize their hiding power. This extension of the prime white pigment can improve opacity and reduce cost.

Unlike ground calcium carbonates (GCCs), which come in just one shape regardless of size, PCCs can be made in many shapes and smaller sizes not achievable by mere grinding. The needle-shaped aragonites and clustered scalenohedral calcites are typical crystal types used as extenders to increase opacity and porosity for dry hiding while smaller prismatics of very uniform particle size can increase film integrity.


Such differences in precipitated calcium carbonate crystal morphology and size can lead to major differences in how a particular PCC performs in different coating formulations. Many PCC products for paint are available in the form of water slurries which maintain the dispersion of the manufactured particle and avoid the need for a production step to redisperse the dried powders.

PCC, much like ground carbonate, finds its largest application in interior and exterior architectural coatings. There is some use in powder coatings—especially the fine and ultrafine nano grades—whose small and narrow particle size distributions promote “Class A” finishes. In addition to the standard, uncoated hydrophilic grades, some PCCs are available in stearic acid-coated versions. These versions increase hydrophobicity, dispersibility, and compatibility in solvent-based or 100-percent solids coatings.

The degree to which precipitated calcium carbonate  are considered standard raw materials for paint formulations varies from region to region. PCCs are common in decorative paints in Europe, South America, and Asia, but less common in North America. The choice generally depends on the relative availability of other extender minerals in the region as well as relative costs.

Specialty Minerals Precipitated Calcium Carbonates for Paint
PCCs for paint are manufactured by Specialty Minerals Inc. (SMI) in Europe, the U.S. and Brazil. The typical uncoated products recommended are:

  • Calopake F PCC.pdf is a 2 micron clustered scalenohedral calcite PCC used for exceptional brightness and titanium dioxide extension. It is manufactured in SMI’s Birmingham, U.K. facility.
  • Sturcal F PCC.pdf is a 2.8 micron acicular aragonite, manufactured in Birmingham, U.K.
  • Albacar® 5970 PCC is a 1.9 micron scalenohedral calcite manufactured in Adams, Massachusetts.
  • Albacar®  8101 PCC is a 1.4 micron scalenohedral PCC manufactured in Adams, Massachusetts.
  • Albafil® PCC is a fine, 0.7 micron prismatic calcite manufactured at SMI’s plant in Adams, Massachusetts.

Nano or ultrafine PCCs are produced in SMI’s PCC plants in Adams, Massachusetts, and Birmingham, U.K. 

  • Calofort S PCC.pdf – is a 0.07 micron nano PCC and is stearic-acid coated. It is manufactured in Birmingham, U.K.
  • Ultra-Pflex® PCC is a 0.07 micron coated nano PCC and is manufactured in Adams, Massachusetts.
  • Calofort U PCC.pdf and Multifex-MM Ultrafine PCC.pdf  PCCs are 0.07 micron nano PCCs and are uncoated for more hydrophilic applications. These PCCs are manufactured in Birmingham, U.K. They are sold in the U.S. under the Multifex-MM® PCC name and in the rest of the world as Calofort® U PCC.

Specialty Minerals Talcs for Paint and Coatings


Talc is one of the most widely used extender minerals in paint. It is used in exterior and interior architectural paints, semi-transparent and opaque wood stains, specialty coatings, and industrial/OEM (original equipment manufacture) applications. Talc is a true functional extender mineral. Its platy structure, hydrophilic surface, and inert chemistry help in the formation of coatings that provide a real moisture barrier. The platy structure also promotes a strong, flexible film.

Talc is the least hard of the industrial minerals—rated as 1, the lowest, on the Moh’s hardness scale. This softness makes it a particularly good additive in sanding primers.

When ground to an ultrafine size, 1 micron median, talc can be used to control gloss and sheen in industrial coatings.

Another talc application in coatings is in predispersed liquid colorants used for in-store tinting of paints. Talcs help keep the pigments suspended and deagglomerated and maximize development of tinting strength from the prime pigments used in the colorant.

Specialty Minerals Talcs for Coatings
Specialty Minerals Inc.’s (SMI’s) Talcron® talc products come in a wide range of particle sizes and size distributions and are useful in a broad range of coatings applications.

Standard 325 mesh filler talcs find use in exterior and interior architectural or decorative coatings as film reinforcement and moisture barrier additives and contribute to improved weatherability. Finer grades are used in sanding primers and in maintenance coatings. The finest products are used as gloss and sheen materials in both architectural and industrial coatings.

All SMI’s talc products for paint are mined and processed in our Barretts, Montana facility.  We recommend the following products for paint:

Specialty Minerals Products for Specialty Coatings

The “specialty coatings” group is a catch-all containing a wide variety of products used in applications which fall outside those covered by architectural paints or industrial OEM (original equipment manufacture) finishes. The technologies for some specialty coatings are closely related to those for industrial or architectural coatings. A good example is the relationship between OEM automotive coatings and automotive refinish paints, with the latter considered a specialty coating.


This category also includes road marking or traffic paints, maintenance coatings for bridges and storage tanks, other metal-protective uses, marine coatings, roof coatings, and aerosol paints. These finishes often mimic the properties and performance of OEM coatings without the luxury of being applied in the controlled environments from which OEM coatings benefit. Specialty coatings are primarily protective coatings rather than appearance coatings. They first perform the appointed task and then look good doing it.

Minerals in Specialty Coatings
Because many specialty applications require very high performance, ingredients are chosen primarily for their functionality and effectiveness with cost a secondary factor. Metal-protective maintenance coatings can effectively employ talc’s barrier properties.

However, there are other cases, such as traffic coatings, that must meet minimum performance standards within tight cost parameters. In road marking paints, which make heavy use of fillers, the ability to reduce overall formulation cost becomes paramount in the choice of one extender pigment over another. Ground calcium carbonate (GCC)–a more economical mineral–is generally employed. In some very specialized coatings, such as aerosols or mirror coatings, there may be just one extender system that truly complements the particular set of other raw materials used in the formulation. Often, in dealing with these more exotic systems, only in-house knowledge and experience can provide the best overall solution.

Specialty Minerals Products for Specialty Coatings
Formulators of marine, maintenance, traffic, and other specialty coating products will find value in one or more Specialty Minerals Inc. filler and extender pigments. These include talcs, ground calcium carbonates, and precipitated calcium carbonates.

Specialty Minerals Ground Calcium Carbonate for Paint and Coatings

Ground calcium carbonate (GCC)—also called ground limestone, whiting, or chalk—is the most widely used extender mineral in coatings applications. It is available worldwide and close to most paint manufacturing locations. It is very bright and comes in a wide range of particle size distributions. Finally, it is the most economical of all common filler minerals.


The widest use for GCC is as a filler in architectural or decorative coatings. While it is primarily used in interior paints, it is included in some exterior formulations as well. It tends to be the filler of choice for paints sold at a low price point and/or where longevity is not the primary attribute. That said, GCC is also used in top-of-the-line flat or matte finishes. 

High-brightness calcium carbonates are selected for ceiling paints and other applications requiring high dry hiding and are formulated above the critical pigment volume concentration (CPVC). By combining two or more grades of different particle sizes, thus altering the particle size distribution of the filler package,  manufacturers can adjust the flatness of finish of interior architectural coatings and improve the scrubability of the final paint film. GCC can be used in exterior building paints as long as the pigment volume concentration (PVC) is not too high. The PVC must be sufficiently low with enough binder present so that the film does not become too porous over time.

GCCs are also economical extenders included in road-marking and traffic-paint formulations to lower costs while still meeting the optical specifications for the finished film.

Although GCCs have many desirable traits, it is not a universal extender mineral. It will react with acids, so its use it limited to areas where it will not be exposed to acid rain or other acidic fumes or liquids. In contrast to high-aspect ratio platy talcs, calcium carbonates, with their round or nodular particle shape and low aspect ratio, make relatively little contribution to improved film formation and integrity and will increase film porosity. For these reasons, the use of GCCs are limited in industrial, marine, and metal-protective maintenance coatings.

Ground Calcium Carbonates from Specialty Minerals
GCCs are mined and processed in the U.S. at Specialty Minerals Inc. locations in Adams, Massachusetts and Lucerne Valley, California. Key products for the paint and coating industry are: