The materials below are used by cultivators as a means of
humidification in place of perlite. It tends to be easier to work with
it than perlite since it keeps the form and doesn't disintegrate and
emit dust.
LECA is short for LightWeight Expanded Clay Aggregate. It has been used
most notable in the Horticulture industry as a planting medium for
hydroponics but has been found useful for many other applications.
Brand names include Hydroton, Geolite, HydroKorrels, Hydroleca, "grow
rocks" ...
LECA is made by baking pure natural clay at 1200 degrees Celsius for 3
hours in rotary kilns, the end product is pH neutral, doesn't degrade
and is autoclavable. Capillary action on the surface of the lightweight
pebbles allows it to absorb 40% of it's weight in water and also allows
for efficient evaporation to help maintain a constant humidity level.
LECA is widely available through Hydroponics outlets, many garden
centers (orders may be available) and also through many concrete
companies, quantities greater than a ton may apply for purchases but
frequently if you tell them you only need a few pounds they may give it
to you.
A similar product available mostly in Europe is Seramis. (in the USA
Isolite is an equivalent)
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