For help with how Perlite can assist you with your product
needs, research, general information, and even a few wild and crazy ideas.
Q. What is Perlite?
A. Perlite is a naturally occurring siliceous rock that expands 4 to 20
times its original size when rapidly heated to approximately 3,000 °F.
In reality, expanded Perlite is a "popped rock" that is inert,
lightweight, sterile, permanent, incombustible, asbestos-free, non-toxic,
rot and vermin proof and has a neutral pH. OSHA classifies it as a nuisance
dust (see Safety Data Sheet).
How does Perlite expand?
A. Two types of water, H2O and OH (a negatively charged water of hydration)
are contained and internally bound in Perlite ore. When rapidly heated
to an appropriate temperature, Perlite's silicate structure softens and
both types of water turn to steam, blowing or expanding the viscous mass
into a glassy silicate bubble froth consisting of tiny closed air cells
on the inside surrounded by an extremely large broken bubble surface structure.
As an analogy, think of popping popcorn.
Q. What are Perlite's physical properties after expansion?
A. Perlite is a natural combination of mixed glassy silicates making it
inert and resistant to chemical attack, except for hot concentrated alkali
and hydrofluoric acid. It slows thermal conductance, is incombustible
(melts above 2000°F) and has no buffering capability. Each Perlite
particle resembles a glassy froth of bubbles. The internal structure consists
of numerous tiny closed air-filled cells. This structure imparts lightness,
natural insulating properties and limited compressive strength. Liquids
cannot penetrate the cells. Perlite's external surface is composed of
broken bubbles surrounding the closed frothy cells and is open, extremely
large and jagged. This irregular surface adsorbs or holds matter making
it an ideal filtration media. In horticulture, Perlite's surface helps
keep planting media open and lightweight. It provides a pathway for air
and moisture to access plant roots. It holds moisture and nutrients for
assimilation by roots over time. Perlite's high capillary action benefits
hydroponic growing and its sharpness can scarify pests as well as act
as a polishing agent and scrubber in various products.
Q. What elements are found in Perlite?
A. Typical elemental analyses show that Perlite contains silicon, aluminum,
potassium, sodium combined with oxygen and other trace elements. Each
Perlite ore deposit has separate and distinct ratios of these mixed glassy
silicate which explains why certain deposits are better for specific applications.
(see Typical Elemental Analysis table)
Q. Does Perlite come in different sizes and weights?
A. Perlite is available in its crude ore form and in expanded product
grades. Densities range from as high as 80 lbs./cu. ft. for ore and as
light as 3.0 lbs./cu. ft. when expanded. A specific application dictates
which product grade is most compatible.
Q. What Perlite products does Supreme offer?
A. In certain cases, we can tailor products for your specific use. In
general, we make products for horticulture,
construction and industry.
Horticultural Perlite is sterile and has a neutral pH. When used in propagation
and planting media, it insures excellent aeration and drainage. It also
lightens media and increases total pore space for healthy root growth
and development. Perlite keeps media open and friable so that plants can
be transplanted with minimum root tear. Those pesky garden weeds can be
easily pulled too!
Q. Does Perlite help fertilize plants?
A. No. Perlite is sterile with no nutrient release. However, Perlite will
retain moisture and nutrients on its surface area for use by the plant.
Normal fertilization and watering routines must be used. Perlite offers
no buffering or cation exchange.
Q. How can I tell if my planting mix is amended with
A. Give the "little white particle" the thumbnail test. There
are three prevalent soil amendments in the northwest and they are all
white or off-white. Push your thumbnail into the middle of a particle.
If it springs back, it's polystyrene. If it's resistant to breakage, it's
pumice. If you can put your nail through it with moderate resistance,
Q. How does Perlite's light weight help?
A. Reduced media weights will lighten workers' loads when handling plants
or media. Lighter planting media decreases worker injury potential. Also,
reduced shipping weights result in more product shipped per truckload.
Q. Can landscapers benefit from using Perlite?
A. Absolutely! Perlite changes soil structure. Clay soils will drain better
while sandy, droughty soils will retain more moisture. Perlite amended
planting areas are easier to work with weed-pulling a snap. Rooftop gardens,
balcony planters and movable planters all can benefit from decreased weights.
Fully watered soil weighs up to 125 lbs. per cu. ft. whereas a well wetted
Perlite/peat moss mix weighs as little as 40 lbs. per cu. ft.
Q. Why is Perlite used in construction?
A. Perlite is substituted for sand or heavier aggregates in concrete and
plaster mixes to reduce weights and achieve better insulation and fire
protection. Perlite is naturally incombustible, resistant to thermal transmission
and lightweight. Using lighter Perlite materials means that, in turn,
structural building elements can be smaller, lighter and less expensive.
Q. What construction applications utilize Perlite?
A. Applications of lightweight Perlite concrete and plaster include roof
deck construction, non-load bearing curtain walls, floor fills, slabs
on grade, floating floors, chimney-lining systems, underground pipe insulation,
bricks, tiles, fire door cores, radiant floor heating, in-ground swimming
pool base and loose fill insulation.
Q. What about Perlite's insulation uses?
A. Perlite's R-value is nearly 3.0 per inch at 6-lbs./cu. ft. density.
It registers 0,0,0 on ASTM's E-84 fire tests for flame spread, fuel contribution
and smoke density. Water resistant, silicone treated Perlite is poured
directly from the bag into cmu block and cavity walls. UL Design U905
shows that a 2-hour fire rated 8", 10" or 12" concrete
block wall improves to 4-hours when cells are filled with water resistant
Q. What industrial applications benefit from Perlite?
A. Perlite is used as a filler, extender and texturizing agent in numerous
products. It displaces expensive resins and reduces unit weights. Perlite's
filler applications include caulks, textures, joint and taping compounds,
paints, polishes, hand cleaners and explosives. Additional uses include
filtration, waste water treatment, oil clean-up, sludge solidification,
exothermic toppings, slag treatment, insulating refractories, low density
well drilling mud, foundry core and molds, formed products, shipping dunnage
Q. What are future uses of Perlite?
A. Future Perlite uses will evolve out of a better understanding of its
attributes, improved processing capabilities and knowledge of synergies
realized when combined with other products. Some possibilities are:
with much less water
bromide replacement growing cultures
Stronger aggregate for lighter but stronger