Overview: Whitewash is a term used to describe the product and process of suspending hydrated lime in water, along with salt and sometimes other compounds (such as an insecticidal dust), to create a slurry that is applied to a surface. This slurry undergoes a chemical reaction that raises the PH to >12 forming a highly alkaline suspension. When applied to a surface, this slurry introduces a uniform highly alkaline coating that has been scientifically proven to effectively disinfect by destroying the cell wall of contacted pathogens. As the whitewash dries, is forms a uniform coating on the treated substrate that provides both a physical and chemical barrier between the substrate and overlaying environment preventing further pathogen transfer. This barrier also creates an environment that is detrimental to many insect pest, such as the darkling beetle (Alphitobius diaperinus), and can be an effective treatment to insect pest if certain insecticides are added to the slurry.
Supporting Data: Pilotto et al.1 evaluated the effectiveness of hydrated lime, caustic soda, 2 phenols, iodine, glutaraldehyde, and quaternary ammonium on disinfecting the dirt floor of breeder houses by reduction in total and fecal coliforms using the MPN method. Hydrated lime was proven to be the most effective method of disinfection reducing the initial contamination by 2.9 log a 99.87% reduction. In the same study, In vitro test also confirmed the effectiveness of hydrated lime as an antimicrobial on Escherichia coli (E. coli) isolates from the poultry house environment.
Bennett et al.2 evaluated the effect of hydrated lime on the survival of Salmonella enterica Serovar Enteritidis (SE) in used poultry litter. The study found that hydrated lime significantly reduced the recovery of SE colony forming units at all inclusion levels and the reduction was achieved immediately.
Watson et al.3 tested the impact hydrated lime had on darkling beetle Alphitobius diaperinus survival in turkey litter. Results showed that hydrated lime significantly reduced darkling beetle survival at higher inclusion rates and was more effective on larvae than adults. If darkling beetle control is a goal of a whitewash treatment, Rabon dust can be added to further enhance the effectiveness of treatment.
1. Pilotto F, Rodrigues LB, Santos LR, Klein WA, Colussi FM and Nascimento VP, Antibacterial efficacy of commercial disinfectants on dirt floor used in poultry breeder houses. Brazilian Journal of Poultry Science 9:127-131 (2007).
2. Bennett D, Higgins S, Moore R, Beltran R, Caldwell D, Byrd J and Hargis B, Effects of lime on Salmonella enteritidis survival in vitro. J Appl Poult Res 12:65-68 (2003).
3. Watson DW, Denning SS, Zurek L, Stringham SM and Elliott J, Effects of lime hydrate on the growth and development of darkling beetle, Alphitobius diaperinus. Int J Poult Sci 2:91-96 (2003).