The best bottlewash detergents are formulated products, rather than a single chemical, such as nitric acid, preferred by some of our French colleagues. Several bottlers were, or still are, from the farming community and nitric acid is ideal for some dairy applications, but not for washing polycarbonate bottles.
The most important consideration in formulating a product is to take account of the different types of water in which bottles are washed. Often the actual spring water is used as the wash water and this may contain high levels of salts. Calcium, magnesium and iron are the main elements which can affect wash performance. Some bottling plants use a water softener, but this is the exception rather than the rule.
A major part of the formulated product has to contain water softening ingredients, otherwise soils will not be removed. Remember, too, that the heaviest soiling is on the outside of the bottle. For added wetting effectiveness on polycarbonate, the product should contain a detergent and some alkali to enhance soil removal. If the product also contains a disinfectant component this will be an added bonus. Formulating a disinfectant component into a bottle wash detergent can be difficult because of potential incompatibility problems, but it is possible.