GENERAL FILTRATION stocks and distributes the excellent HESS pumice grades that are used in a wide and quite amazing variety of products and industries. Chemically inert and crystalline silica-free, HESS pumice is both safe to use and safe for the environment.

Pumice Concrete & Construction Materials

Pumice concrete has several advantages over conventional concrete in many construction applications. Most significant is its unique lightweight quality. Other key factors such as workablility, resistance to harsh weather conditions and a high R-value make pumice concrete the choice for demanding construction needs.

Manufactured (man-made) stone veneer is an enduringly popular exterior and interior finish that imparts the sculpted durablity and beauty of stone finishes without the cost and the weight of natural, hand-cut rock. Pumice is the key ingredient to this lightweight construction material.

Lightweight concrete block made with HESS Pumice is the whitest masonry available—desireable for exposed block applications such as fireplaces, planters and walls.

Due to the exceptional insulating properties of pumice, it is also used as a cavity fill for concrete block walls.

Polishing & Abrasives

HESS pumice is used extensively worldwide for critical surface finishing processes—its friable particles fracture and remain sharp-edged when processed to even the sub-micon size—making it ideal for use as a mild abrasive for finishing glass, metal, wood, leather and plastics.

Pumice is also the mild abrasive of choice in exfoliating soaps and cleansers, tumbling media, erasers, dental polishing compounds—even stone-washed denim.

Fillers and Extenders

The near-white color of HESS pumice, coupled with its chemically and environmentally inert nature, makes it an appealing choice as a filler and extender. HESS produces six NCS grades for use in paint, industrial coatings, stains, rubber compounds and plastics.

Cementious Grout

A division of HESS Pumice, produces an ultra-fine cementitious grout composed of a finely ground mixture of Portland cement, pumice and dispersant. The ultrafine grout has an average particle size of only a few microns, in stark contrast to typical particle sizes of 60 to 70 microns in conventional cements. This ultrafine grout is ideal for penetrating and sealing extremely small fractures and for fine-grained soils.

Liquids Filtration

Pumice is an effective filtering media for drinking water. The foamy structure and near-white purity of HESS pumice makes it ideal to capture and hold cyanobacterial toxins and other impurities found in fouled drinking water.

The excellent filtration and absorbtion properities of pumice make it useful for other cleaning and filtering uses, such as purifying oils or removing odor.

Blast Mitigation

Pumice collapses at a cellular level beneath the force of the blast, absorbing much of the blast energy and effectively containing the damage. Lightweight, abundant and easily processed to any spec, pumice is proving to be effective and economical. BAE Corporation currently uses HESS pumice as blast mitigation media in missile and bomb encasements.

Soil Conditioner

Because of its highly porous nature, pumice holds water and air—both critical to well-conditioned, aerated soils. This makes HESS pumice an excellent soil conditioner for use in potting media and garden soils—and even for critical and hard-used turf applications such as golf greens and sports fields. Because pumice is non-organic, it will not decompose or burn. Pumice is also pH neutral.

Other Possibilities & Uses for Pumice

Pumice is finding its way into more and more applications and industries that have traditionally relied on other materials. For example:

• As a high-pressure (blast) cleansing media. The softer, gentler abrasion of pumice is replacing the harsh bite of sand in sensitive blasting applications, such as the restorative cleaning of grime and neglect from historic buildings and other constructs.

Textile softener and conditioner. The popular process of stone-washing has successfully relyed on pumice to get the job done. Light, carefully sized and rounded pumice stones and specially-designed washing machines combine to soften and condition the appearance of denim and other fabrics.

Chemical filtration and transportation medium. For example, pumice is used as a solid carrier-base for spreading fertilizers as well as pesticides and other problem-controlling chemicals. And once it has given up its chemical rider, the pumice remains to condition and improve the soil.

Hydroponic medium. Pumice is becoming widely accepted in hydroponic growing processes because it drains readily, is easy to flush and keep clean, does not deteriorate—remaining strong and durable, does not interfere with the transmission of nutrients to the growing plants or damage roots, and does not readily absorb heat from ultraviolet or direct sunlight.

Control and clean up spills and smother fires. Think of pumice as a mineral sponge: inert, stable, lightweight and much more effective than sawdust, clay compounds and textiles. The absorbtion factor of carefully processed pumice is incredible—rating in excess of 77 percent.

 • Fine arts paint additive. Lends a matt (or less shiny) appearance to dried paint; adds texture and body without shifting the color; added to chalk and gesso grounds gives "tooth".


Key Features of Hess Pumice

  • Extremely high purity content (98% - 99.8%)
  • Low unit weight (40 - 45 lbs per cubic foot)
  • Consistent MOHS of between 5.5 and 6.1
  • Superior friability characteristics
  • Reported performance benefits of 25% - 50% over all other pumice worldwide
  • Near white color useful in many filler applications
  • Custom blending to meet the most exacting customer specifications
Amorphous characteristics pose no health risk (MSDS).

Continuous testing ensures superior quality. The most common tests performed in-house include:
  • Sieve Size Analysis (ASTM C-136)
  • Particle Size Analysis by Laser Diffraction (Coulter Method)
  • Whiteness (Datacolor “Check” method)

Typical Screen Analysis of Standard Grades Average Percent Passing Sieves

The above graduations are only typical. Normal production tolerances from the typical will be permitted. A trace is allowable on the next coarser sieve. (Click chart image above to enlarge; or download printable version)