The stink over Chinese drywall

Sunday's column mentioned the widely reported misuse of coal fly ash in sulfur-bearing wallboard imported from China. Associated Press stories have repeated the assertion, but an official with National Gypsum in Charlotte says fly ash is not the problem with imported wallboard.

Gerard Carroll, senior vice president for manufacturing operations and engineering, says the problem with Chinese wallboard is that it contains naturally mined gypsum with a heavy concentration of sulfur. "It was produced from natural gypsum mined from a deposit in China that contained elemental sulfur. In certain environments the free sulfur reacts with ambient moisture and can cause the corrosion and other problems that have been reported. As far as I know, this situation of elemental sulfur contaminated gypsum ore is unique to China," Carroll said.

News reports for the last year or so have widely attributed the problem to misuse of coal ash in Chinese wallboard.

Reports, as the column noted, are that the wallboard, installed in Southeastern U.S. homes after Hurricane Katrina when domestic wallboard was harder to get, has sickened residents, degraded electrical wiring in homes across parts of the South and ruined the lives of many. The Consumer Product Safety Commission says the imported wallboard should be removed from U.S. homes.

Sunday's column also said, that U.S. producers of wallboard such as National Gypsum use some byproducts from stack emissions to produce calcium sulfate, the chemical name for gypsum, but they say they do not use fly ash in wallboard. The domestic wallboard has not caused problems.