[APD] Re: Substrates

[Wright Huntley <whuntley at verizon_net>]

This group needs an experienced aquarist with a strong background in 
non-metallic minerals. Then maybe the conjecture level could be lowered 
a bit by some facts. :-)

I'm not that person, but maybe I come closer than others. I was an 
electrical engineer, specializing in lasers and optics, but I grew up in 
the industrial minerals business, and worked in it for my father on 
several occasions. [He owned the world's largest producer of general 
non-metallic industrial minerals, and I worked in the mines, the mills, 
and the laboratories, as a kid (and half way through college).]

Some of the statements here clearly forced me to recall the processes of 
baking, calcining, firing, etc. that bear on the production of synthetic 
or altered substrates. They were the same processes used in industry to 
incorporate his products like feldspar into the old pre-vinyl records, 
for example.[For you youngsters, records were audio things played with a 
needle before we had DVDs. :-)]

The various materials, laterite, Fuller's earth, clays, micas, etc. are 
all pretty well understood, and should not be a big mystery when used as 
substrate. A "Dogpile" search will overload you with information.

I'll leave the materials for now, but mention a bit about heat processes.

Baking: Low temperature that mostly drives off moisture to make clays 
rigid, but they can be pretty fragile and delicate, depending on what is 
in them. In pottery this is the process for making "greenware" before 
glazing and high-fire finishing. It's great for making nutrient-filled 
clay balls that will gradually break down and release stuff into the 
substrate.

Calcining: Literally it is higher temps used to drive off CO2 from 
limestone to make lime, as a part of the process of making Portland 
cement. In common use, it is any hot drying process that may or may not 
involve some fusion to create a more permanent hard product. It may also 
drive off water of hydration to alter the chemical and physical 
properties of a mineral.

Firing: Even hotter, such that fluxing agents in clay melt and fuse the 
material to a hard, even a glassy state -- ceramic. High fire produces 
stoneware and porcelain. Low-fire produces terra cotta, like common 
plant pots or aquatic substrates like APS and Flourite. [I suspect they 
are fired hotter than normal calcining, but don't really know.}

Wright

--
Wright Huntley - Rt. 001 Box K36, Bishop CA 93514 - whuntley at verizon_net
                      760 872-3995

 "France has neither winter, nor summer, nor morals. France is 
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               http://www.libertarianism.com/


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