Re: Rockwool

From: T. Williams (
Date: Wed Jan 20 1999 - 19:01:50 PST

Date: Thu, 21 Jan 1999 12:01:50 +0900
From: "T. Williams" <>
Message-Id: <aabcdefg176$foo@default>
Subject: Re: Rockwool

Rockwool might be fine for plugging up the bottom of pots, but one would be
treading on thin ice to suggest that it does not break down. Time, tide and
especially the effects of water will break down anything eventually, including
rocks. Not knowing the origins of a particular brand of rockwool I would be
inclined to treat it with distinct suspicion until tested (and preferably not
on one's own collection). The extremely high surface area of rockwool fibres
would greatly facilitate leaching out of any alkali metal ions when in contact
with water, acid or otherwise. I'd like to bet that like many other silicate
minerals, "rockwool" is choco with leachable ions covering half the periodic
table. For anyone out there working in a University with a half-decent chem
department testing this would be a trivial matter.

Take care,

Tim Williams.

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