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Physical Appearance
Perlite is a pH-neutral, sterile, volcanic rock of the family of amorphous silica; its color ranging between white and gray. It comes in granules of different sizes and densities:
Fine perlite (0-2 mm);
Medium perlite (1-3 mm);
Horticultural perlite (2-5 mm)
Perlite Characteristics
Perlite is one of the best hydroponic growing mediums around. Used by itself or as a mixture with other mediums. Perlite is commonly used with vermiculite ( a 50 - 50 mix is a very popular medium), and is also one of the major ingredients of soiless mix's. perlite has good wicking action which makes it a good choice for wick-type hydroponic systems. Perlite is also relatively inexpensive.
The biggest drawback to perlite is that it doesn't retain water well which means that it will dry out quickly between waterings. The dust from perlite is bad for your health so you should wear a dust mask when handling it.
Properties
Expands when heated: Crushed perlite has the property of expanding when heated at varying temperatures between 900o to 1100o C. Its volume may increase four- to twenty-fold.
Porous texture: Surface pores or cavities develop on perlite particles during dilation. These pores trap moisture on which plant roots thrive. Perlite particles are irregular in shape and leave air passages in the soil at the base of plant cultures, for optimal aeration.
Liquid retention: Perlite’s porous texture retains moisture and fertilizers. With appropriate granule size, perlite provides optimal irrigation as well as perfect drainage for all your horticultural projects.
Air circulation: Because of their irregular shape, perlite particles provide aeration in growing mixes and substrates, and in many industrial applications.
Low density – cannot be compacted: Since heated perlite increases in volume while keeping the same mass, expanded perlite has a very low density which, combined with its other characteristics (neutral pH and porous texture), makes it an ideal filling material which cannot be further compacted.
Chemically neutral: Perlite is an odorless, non-flammable, and non-explosive chemical; an inorganic component which does not deteriorate. Other benefits of horticultural perlite are its neutral pH (6.5 to 7.5) and the fact that it is sterile and weed-free. These reasons explain its popularity for various applications from window boxes to filtration in pharmaceutical and food industries.
Horticultural Applications
In horticultural applications, perlite is used throughout the world for its numerous qualities and for an incredible variety of applications:
Soil improvement and conditioning: Perlite is very useful in soil conditioning in order to ensure optimal moisture retention, improved aeration, drainage, and to control weight and temperature variations.
Irrigation of heavy soils: When added to compact clayey soils, perlite helps eliminate surface cracking and water accumulation.
Growing mixes: Whether for indoor or outdoor plants, perlite is used worldwide to provide soil aeration and optimal moisture retention, making root penetration easier, thus maximizing growth.
Indoor plants – Hydroponic culture: Lightweight perlite-conditioned soils make it easier to manipulate containers and growing benches. Studies have shown that hydroponic systems using perlite achieve outstanding yields.
Seedlings and root cuttings: Added to soil, perlite particles leave enough space to greatly improve root penetration. It retains moisture, promotes aeration and drainage, and cannot be compacted. Perlite combines all the optimal conditions for the development of your cultures.
Conservation of bulbs and root-plants: Combined with its other qualities, perlite’s insulating capacity makes it an ideal material for the conservation of bulbs and root-plants over long periods.
Mixes with peat moss: Mixes with peat moss and perlite are lighter for cheaper and easier transportation.
http://www.perlitecanada.com/en/1-perli ... icole.html
