From:
John Twilley <jtwilley@zzzzzzzzzzz>
Date:
Fri, 23 Jan 2004 12:06:46 -0500
Subject:
Carving Raised Letting in Georgia Marble
Norman,
Re: question 2
Marble has a high porosity between the grains. Gypsum has enough
solubility (around two tenths of a percent by weight in typical ground
water) that it is effectively transported by water, especially when that
water persistently goes in the same direction say, by wicking up through
the base and evaporating out of the surface of the monument. The gypsum
recrystallizes near the marble surface where the water evaporates and
the growing gypsum crystals loosen the marble grains. It will take some
time to do damage but the process starts with the first movement of
moisture through the plaster.
This is a problem that is universal to stone in buildings and monuments
the world over.
John Twilley
- References
- message 00324: Carving Raised Letting in Georgia Marble - Simon Brown (23 Jan 2004)
- message 00326: Carving Raised Letting in Georgia Marble - John Twilley (23 Jan 2004)
- message 00327: Carving Raised Letting in Georgia Marble - Norman Watts (23 Jan 2004)
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