Pumice is amazingly versatile, with uses found in various industries, including agriculture, horticulture, landscaping, filtration, concrete infrastructure, manufacturing, even cosmetics and other consumer goods. These uses, and more, are detailed briefly below.
Horticulture
The water-holding, soil-structure-enhancing, foamed-stone form factor of every tiny pumice stone is an ideal component for engineered potting soils, raised-garden and lightweight roof garden soils, bonsai hobbyists, and high-efficiency soilless ’ponics-style grow systems.01 Pumice is lightweight, holds moisture yet readily drains (it does not swell or get soggy), stays locked into the soil matrix, holding open the pore spaces for breathability in the root zone, and does not breakdown over time—as an inorganic stone, it is not consumed. The pocked, nook-and-cranny surface of every pumice particle also provides an enduring scaffolding to support beneficial soil microbe colonies. Performance-wise, pumice is the physicochemical equivalent of expanded perlite, and can be directly substituted for perlite in potting soil and garden soil mixes.02
Greenscaping
Greenscaping, or vegetative landscaping, relies on good soil to support the plantings for the long term. Unlike annual renewal-gardening, where the soil can be tilled and conditioned anew, the landscape sculpting of parks, green belts, building grounds, yards, and sports fields is a build-it and keep-it effort. Maintenance, yes, but replanting and reshaping are, at best, infrequent. In areas with poor native soils, building out a water-wise, thriving landscape is a challenge. Conditioning the soil is the answer. Compost works, but compost alone does not endure—once consumed, the soil structure collapses to its previously poor state. Liberally tilling pumice into the soil (often combined with compost, if kick-start nutrients are needed) will amend the soil-structure permanently, resisting compaction, managing moisture uptake, facilitating drainage, and providing the other in-soil benefits previously mentioned. Economical fines-loaded mine grades03 work beautifully for this purpose.06
Agriculture
Pumice is used in the vast agriculture complex on two levels—field crops and animal husbandry.
Soils. Mediocre soils, especially heavy clay soils, have poor tilth—they need ongoing mechanical tillage to combat compaction and maintain viable root zone structure. Tilling in a layer of eight-inch fines MN (mine grade) pumice03 into these poor native soils permanently improves the grow-zone structure in terms of aeration (breathability), drainage, and moisture retention. Pumice is the only economically viable solution for these large-scale soil amendment projects. As water usage demands, wind erosion control, fuel costs, and other factors increasingly affect farming operation costs, building no-till, high-performance crop soils becomes increasingly attractive for the bottom line, especially when growing perennial crops, or establishing orchards, berry fields, and vineyards.
Seeds. Small and/or irregular-shaped crop seeds are typically coated to ensure smooth flow through seed drill implements and to provide a kick-start jacket loaded with nutrients, fungicides, and/or a moisture attractant. Powdered pumice, in augmented slurry form, is used as the base component carrier to form these seed-shaping jackets.
Livestock. Confined animal operations deal with a pair of issues—moisture and manure—and the odor that comes with them. Pumice can be layered with bedding materials or used alone to control moisture and odor from urine and manure. Controlling the ground moisture also helps to disrupt the relentless life-cycle of flies and mitigate the issues they cause. When the manure and bedding waste is composted, pumice contributes to the composting process itself, then later functions as a long-lived functional and structural component in the soil the finished compost is added to.
Composting
Compost is a valuable, renewable resource: it provides a nutrient boost to hard-used garden soils and recharges poor native soils. The addition of pumice03 to the composting process provides a dual benefit—pumice actively improves the composting process and then serves as an enduring, inorganic structural component of the finished compost in-soil.
In-Process. Research studies that mixed pumice with the organic feedstock found that pumice provided a buffer to the volatile compounds created during the decomposition process and mitigated nitrogen loss. Pumice also provides inert bulk within the composting rows or bins, improving critical airflow.04
In-Soil. For all of the reasons detailed under the horticulture, greenscaping, reclamation, and ag topics, pumice and compost make a valuable, highly effective blend, with the compost providing a nutrient kick and long-lived pumice providing functional structure within the soil matrix.
Reclamation
Closely related to the issue of poor native soils in ag crop fields is the process of reclamation from construction and mining operations, where erosion-controlling, return-to-nature vegetation needs to be established quickly to anchor construction-disturbed soils (top soil blended with mineral sub-soils). Hydro-seeding with mulching covers are widely used, but have a high failure rate.05 Conversely, pumice-blended composts that are churned into the disturbed and or poor native soils jumpstart the establishment of a quality topsoil, with the compost providing the consumable soil nutrients and the pumice rebuilding—permanently—the soil profile, establishing a functional rootzone in terms of air-exchange breathability, drainage, and nutrient and moisture retention. Built upon that foundation, reseeding efforts become much more successful.
Surge water management constructs—soil-based structures like ecology embankments, bioswales, roadside filtration strips, wetlands—can also be functionally enhanced from blending truckloads of mine-grade pumice into the native soils. The pumice works to hold open the soil structure and allow drainage. The profusion of foamed-stone pumice particles filter and capture contaminates from hard-surfaces like roofs, roads, and parking lots. Vegetative cover roots deep and stays healthy.
Such large-scale reclamation soil improvement efforts are only economically viable when using by-the-ton pumice mine grades.03
Concrete and Construction
Pumice finds wide and historic use in two primary areas in the construction and concrete products industries: concrete-enhancing pozzolans and weight-reducing aggregates.
Pozzolan. Our modern fast-setting Portland cement-based concretes and stuccos absolutely need a performance-enhancing pozzolan to endure. A waste by-product (fly ash) from the coal-fired electricity generation plants primarily did the pozzolan job for decades, but natural pozzolans are once again filling the void left by the contraction of the coal-power industry, with pumice leading the way. Enduring Roman concretes are a testament to the importance of a pozzolanic component to any concrete mix design, especially for long-lived infrastructure.07
Concretes begin deteriorating almost as soon as they’re poured. They come under attack from sulfates, from the freeze-thaw cycle, from reactive issues within the concrete matrix itself—like alkaline silica reaction (ASR) and efflorescence. Pozzolans, in particular pumice pozzolans, super-charge the chemical reaction that is the concrete curing process, making the hardened concrete stronger, denser, and much more resistant to breakdown, greatly extending its functional life.08
Lightweight Aggregate. Pumice aggregates have long been used for making common lightweight building blocks—concrete masonry units (CMUs)—which are ubiquitous in the construction arena. They are strong yet easy to handle, (and more economical to ship) thanks to the weight reduction provided by using frothy pumice aggregate and pumice sand instead of typical sand and gravel.
Pumice aggregates and sands are also used to pour lightweight insulative concrete walls and slabs, precast tilt-up walls, precast planters and statuary, cast stone and brick veneers of all shapes and sizes, decorative pavers and landscaping stack-blocks, and more. High school and college engineering students annually build and race pumice-concrete canoes.09
Filtration
Pumice makes an aggressive filtration media, especially when compared to sand. That’s because pumice media traps impurities on two levels: between particles and on the particle surface—those abundant, sharp-edged nooks and crannies really grab and hold the gunk. Pumice media is used for the treatment of municipal and industrial effluents. Pumice media is used in sand-filter type tank systems, like for drip irrigation systems that filter emitter-clogging turbidity out of the water. The low specific gravity and high porosity of pumice make it ideal for these applications and treatment processes. Another advantage to pumice media is the wide grade options available, allowing the filtration media to be customized for the job and system type.
The utility of pumice in filtration processes extends to odor control, filtering soils, and purifying beverages and oils as well.10
Manufacturing Processes
Pumice rose to fame in the manufacturing sector (in particular the pumice from southeast Idaho) as a shaping and polishing abrasive in the television glass industry. Currently, pumice fills a well-defined role as an abrasive for a number of shaping, cleaning, and polishing processes, from computer boards11 to machine parts to tumble-shined buttons.
Other processes include mould release powders, spill containment, liquid waste solidification (required before transport and disposal in land fills), cleansing blast media, fillers and extenders for rubber and petroleum-based products, and softening denim.
Consumer Goods
Pumice serves as a functional component a wide range of consumer products. Pencil erasers, dental prophy pastes, rubbing compounds, grime-cutting hand soaps, and exfoliating cosmetics all utilize the excellent abrasive qualities of even the finest grinds of pumice. Paints and coatings, epoxies and caulks use micronized pumice as a safe, non-crystalline filler and extender. Bagged potting soils and composts use pumice as a key inorganic structural ingredient. Bagged concrete mixes, lime plaster products, and bonding mortars blend pumice sand (lightweight properties) and pozzolan powders (performance boost). Pavers, stone veneers, and building blocks all bind lightweight pumice aggregate. Spill containment and animal stall moisture control products leverage pumice’s affinity to attract and hold moisture and its rough, porous surface to grab and hold gunk.
The Pumice Store. Several years ago, Hess Pumice took steps to make a wide variety of their pumice products/grades available to those who didn’t need a ton or a pallet load of production bags, rather, they wanted a pound or two; perhaps a single production bag. This user-type includes those who want bathing dust for a pet Chinchilla or the backyard chickens. Those who want pure pumice grow media for a growing succulents. Those looking to scrub hard water stains from glass. Those wishing to transform a favorite face cream into an effective exfoliant with a fine mix-in grit. Even houseplant enthusiasts looking to create custom potting mixes.
Backed by a dedicated fulfillment center, the Pumice Store facilitates online sales of specifically-purposed pumice products as well as fuels a sampling process for the most popular, widely-used grades Hess offers to those exploring the possibilities of using pumice in their processes or product formulations.
Branded Products. Hess has also created a series of branded pumice products12 focused on specific uses. For example, Chinchilla owners order ChillDust™. Bonsai enthusiasts order Rutsu™ grow media. Woodworkers order powdery Sedoso™ to rub up the final finishes. Those with aquaponic grow systems order bags of Ponics Stone.™ Gardeners looking to improve heavy clay soils order SoilRox.™ These products and others are available via the Pumice Store or can be ordered directly from their own info-rich websites. All of Hess’ branded consumer pumice products are linked from the brandpumice.com directory.
Sourcing Pumice
Hess Pumice Products provides pumice to market at two levels: industrial-use quantities shipped via rail, truck, or ocean container, and small quantities for specific consumer-direct uses via an online Pumice Store backed by a dedicated fulfillment center.
INDUSTRIAL QUANTITIES IN A VARIETY OF GRADES
Hess produces a variety of pumice grade and grade blends, from one-inch aggregate to highly refined powders as small as 3 microns. Email salesteam@hesspumice.com (or call 208.766.4777) for expert help with grade selection and logistics.
SMALL QUANTITIES FOR A VARIETY OF USES
Sample most of our production grades or purchase branded pumice products for specific applications via an online ordering process.
Branded Consumer Pumice Products