Hey Steve,  That's the sort of learned answer I was looking for to my
question about why bricks turn red when they are fired.  Ruth


At 3:50 PM -0500 11/29/05, [log in to unmask] wrote:

>Technical note:  The color change is probably due to  oxidation of Fe2 to Fe3
>in some component in the cement phase in the  mortar, but might alternatively
>be due to deposition of organic matter  in the exterior portion of the joint
>or to simple carbonation of the hydrated  lime in the mortar.  To determine
>what happened, have two petrographic  analyses done; one of an interior sample
>and one across the exterior.
>
>Steve Stokowski
>Stone Products Consultants
>Building Products  Microscopy
>10 Clark St., Ste. A
>Ashland, Mass. 01721-2145
>508-881-6364  (ph. & fax)
>http://members.aol.com/crushstone/petro.htm
--
Ruth Barton
[log in to unmask]
Dummerston, VT

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