Organic gases harmful to museum artifacts are emitted by a wide range of materials used in case construction, including medium density fibreboard (MDF). Several products may provide barriers to the emission of such gases when applied as surface coatings. Fifteen of these were applied to samples of MDF and ZF (zero formaldehyde) MDF. These were places in sealed inert boxes to replicate a case environment, and levels of emitted formaldehyde, acetaldehyde, acetic and formic acid measured. Levels of emitted gases decreased with most of the selanants tested, the exceptions being some lacquers. The lowest levels came from samples coated with barrier foils and charcoal cloth, and higher but significantly reduced levels from Dacrylate and polyurethane lacquers. The varnishes and paints tested reduced levels slightly compared to uncoated samples. For barrier foils the application method and quality had a noticeable effect on sealant efficiency.