Microbial contamination can have a negative effect of a product, or worse be a health risk to users, so it is important to avoid spoilage of the products. Each COLIBRI product is specially formulated for a specific cleaning application. Wherever possible we avoid using preservative, and some of our formulations will preserve themselves naturally. However this is not possible for every formulation and application, so for these we add the minimum amount of preservative required to stop spoilage in the diluted product.