National Gypsum said in a prepared press release that statements made by Dr. Timothy Townsend, in a CBS Nightly News segment aired in December, are misleading and unjustly harming its reputation in the marketplace. Dr. Townsend is a professor at the University of Florida. 

National Gypsum said in a prepared press release that statements made by Dr. Timothy Townsend, in a CBS Nightly News segment aired in December, are misleading and unjustly harming its reputation in the marketplace. Dr. Townsend is a professor at the University of Florida.

The segment implied wallboard produced by domestic U.S. manufacturers is in some instances causing the same problems associated with defective Chinese drywall.

The defective Chinese drywall emits sulfide gases, causing “rotten egg” odors and sulfide attacks and corrosion of copper and other metals in a home including air conditioner evaporator coils and electrical wiring.

The company bases its contention on history and scientific data from leading engineering firms. The manufacturer has produced wallboard in the United States for 85 years with none of the problems now associated with defective Chinese drywall. In addition, National Gypsum engaged Packer Engineering Co., an independent third-party firm, to test its wallboard and known samples of defective Chinese wallboard. Data from Packer Engineering-as well as Dr. Townsend’s data provided to National Gypsum just prior to the CBS broadcast-confirms that National Gypsum wallboard does not and will not cause sulfide attacks or corrosion of copper or other metals, the company said.

“Sulfide gases are found throughout the environment. They can be found in the water we drink, in certain foods, and even in human breath,” said Dr. Eli Stav of National Gypsum’s Technology Innovation Center. “U.S.-made drywall can emit trace amounts of sulfides. These sulfide gases are consistent with what you would commonly find in many places in the normal environment. These trace amounts are far less than 1 part per million, and less than what, in a laboratory test, has been found in a control sample of deionized water” CBS Nightly News reported that it had retained Dr. Townsend to perform laboratory tests over a five-month period. Dr. Townsend’s tests reportedly compared various brands of U.S.-made wallboard, including National Gypsum wallboard, with known defective Chinese drywall found in homes. These samples were also compared to samples of newly purchased Chinese drywall. Predictably, Dr. Townsend’s results show the known defective Chinese drywall emitted large amounts of total sulfide gases, while comparatively small amounts were emitted from National Gypsum’s wallboard.” (Visit for a table of these board samples.)

The defective Chinese board samples in Dr. Townsend’s report show total sulfide emissions in multiple parts per million, many times higher than the totals for any of the National Gypsum board. In fact, the data concerning National Gypsum’s board distributed in the Florida market shows near zero levels of sulfides. A further comparison of National Gypsum’s Florida sample with the defective Chinese samples in the study shows the level of Chinese wallboard sulfides is up to 1,600 times higher. The total sulfide gases reported by Dr. Townsend for the National Gypsum board samples are all trace amounts, less than one part per million. Scientific reports from multiple sources show these trace amounts do not cause sulfide attacks, blackening, or corrosion of copper.

Leading scientists, who presented at a symposium in Tampa, Fla., sponsored by the Florida Department of Health on November 5 and 6, confirmed from their research that domestic wallboard, including National Gypsum’s product, does not produce sulfide attacks, sulfide blackening or corrosion of copper. Dr. Townsend, CBS News’ expert, was among those presenting at this symposium and he also reported that the control sampling of domestic U.S. drywall in his laboratory tests produced no corrosion of copper.

According to these experts, the marker for defective Chinese wallboard is “elemental sulfur.” Elemental sulfur reacts with certain components in the air and with moisture to form hydrogen sulfide gas, which then will attack copper and cause it to form sulfide blackening and to corrode.

The domestic wallboard tested by experts presenting at the Tampa symposium contained no detectable levels of elemental sulfur. Similarly, all of National Gypsum’s board that has been tested by Packer Engineering shows no presence of elemental sulfur.

“With history and scientific data to support our products, we are confident National Gypsum wallboard is not a problem in the current investigation of defective Chinese wallboard,” said Craig Weisbruch, senior vice president, Sales and Marketing. “However, we are very concerned about our company’s reputation and the reputation of our products in the marketplace when irresponsible assertions, such as those aired by CBS News and which misinterpret data and tell only part of the story, are made public.”

The Consumer Products Safety Commission has ongoing investigations into the defective Chinese drywall issue. National Gypsum and other U.S. wallboard manufacturers have worked closely with the CPSC since early 2009, providing samples of their products and raw materials. National Gypsum has voluntarily hosted CPSC tours of its plants to show how wallboard is produced and to demonstrate quality assurance procedures.

The CPSC continues to look at defective Chinese wallboard as well as wallboard produced by U.S. manufacturers and has found significant differences between defective Chinese wallboard and wallboard produced in the United States. Nevertheless, complaints have been made to the CPSC in which some homeowners assert they have only domestic wallboard in their homes and yet have the same problems associated with defective Chinese board.

In some of those cases, defective Chinese wallboard has, in fact, been found in the homes. It is not uncommon for a home to have two or more different types of wallboard in it, including a mix of defective Chinese wallboard and normal U.S. wallboard. In others, where the domestic wallboard has been tested, there has been no elemental sulfur found and the board produced no sulfide blackening or corrosion of copper in controlled laboratory tests.

“There can be a number of sources for hydrogen sulfide, as well as other sulfides,” Dr. Stav said. “That should be determined on a property-by-property basis. However, scientific data from public sources have shown that in Florida, particularly southern Florida, water can be a significant source of sulfide gas.”

While National Gypsum wallboard is not part of the problem associated with defective Chinese wallboard, the company is working with consumers, customers, and government agencies to provide information and find solutions.

For more information on National Gypsum and the defective Chinese drywall issue, visit