Characterization and reduction of formaldehyde emissions from a low-VOC latex paint

The patterns of formaldehyde emission from a low volatile organic compound (VOC) latex paint applied to gypsum board were measured and analyzed by small environmental chamber tests. It was found that the formaldehyde emissions resulted in a sharp increase of chamber air formaldehyde concentration to a peak followed by transition to a long-term slow decay. A semi-empirical first-order decay in-series model was developed to interpret the chamber data. The model characterized the formaldehyde emissions from the paint in three stages: an initial "puff" of instant release, a fast decay, and a final stage of slow decay controlled by a solid-phase diffusion process that can last for more than a month. The model was also used to estimate the peak concentration and the amount of formaldehyde emitted during each stage. The formaldehyde sources were investigated by comparing emission patterns and modeling outcomes of different paint formulations. The biocide used to preserve the paint was found to be a major source of the formaldehyde. Chamber test results demonstrated that replacing the preservative with a different biocide for the particular paint tested resulted in an approximate reduction of 55% of formaldehyde emissions. But the reduction affected only the third-stage long-term emissions.