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From: pamp@bcsaic.UUCP (pam pincha)
Newsgroups: net.columbia
Subject: Re: Columbia's Tiled Damaged by Rain
Message-ID: <246@bcsaic.UUCP>
Date: Tue, 27-Aug-85 17:50:11 EDT
Article-I.D.: bcsaic.246
Posted: Tue Aug 27 17:50:11 1985
Date-Received: Fri, 30-Aug-85 09:44:04 EDT
References: <4010@alice.UUCP> <199@mot.UUCP> <521@calmasd.UUCP>
Reply-To: pamp@bcsaic.UUCP (pam pincha)
Organization: Boeing Computer Services AI Center, Seattle
Lines: 38
Summary: 

In article <1521@peora.UUCP> jer@peora.UUCP (J. Eric Roskos) writes:
>
>This sounds like ordinary ceramic glaze, is that the case?  (I.e., ceramic
>glazes before you fire them are made up of finely powdered glass, mixed with
>a binder and suspended in water; they go on with a texture sort of like
>chalk, but then when fired the glass melts together into a solid surface.)
>I'm not entirely sure what is meant here; are the tiles like this:
>
>	================== <-powdery before, hard after firing
>	oooooooooooooooooo
	oooooooooooooooooo <-silicon "foam" (Froth might be a better
	oooooooooooooooooo   term)
>	oooooooooooooooooo
>	****************** <-bonding site ref'd later in article
>
>or is it the polyurethane-foam-like material that rubs off before firing but
>is hard after?

From what I know of the stuff, basically that it is a silicon
"froth", it is highly likely that you are getting a minor
amount of melting during re-entry. The stuff is so insulating
that only the outer most layer is affected. It just can't take
concentrated point pressures or excessive vibrations -- hence
the rain damage (rain drops at high speed lots of concentrated
force on a small area -- very condusive to compaction.).
------------------------------------------------------------
				P.M.Pincha-Wagener
				(bcsaic!pamp)
(usual disclaimer)
------------------------------------------------------------

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