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Subject:  C&EN: Chinese Wallboard Date:  5/6/2009  1:15 PM
Author:  pauleckler Number:  690 of 821

The May 4, issue of C&EN has an article on chemical aspects of the Chinese wallboard that is causing odor and corrosion in some new homes, especially in Florida.

The basic raw material of wallboard (aka drywall, gypsum board) is gypsum, calcium sulfate. Most is mined in the US but some comes from scrubbing flue gases from coal burning power plants.

Source of the Chinese drywall is not yet known, but analysis suggests it is made from gypsum mined from deposits with contaminants. Sulfur contaminants or metal sulfides are suspected. Pyrite, ferrous sulfide is suggested in some of the wallboard. One study found strontium sulfide in the wallboard.

Analysis of the odors has detected carbon disulfide, carbonyl sulfide, and hydrogen sulfide. In presence of the bad wallboard, copper turns black and corrodes. That is characteristic of hydrogen sulfide (rotten eggs), according to the article.

The odors and corrosion are the main objections. So far toxic levels of the materials in question have not been detected, but occupants of the homes report nosebleeds, sinus problems, and respiratory infections.

Investigations continue.
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