Why are the ingredients in your household cleaners selected?
Just what is their role in helping your cleaner do its job?
In this blog series we break down the basic roles ingredients serve in typical household cleaners. Last week, we explained that household cleaner ingredients fall into one of the following categories: solvents, surfactants, builders, fragrances, preservatives, pH adjusters, and product modifiers.1 In that post, we discussed what solvents and surfactants are and the fundamentals of their functions. In this post, we will discuss builders, fragrances, and preservatives.
Builders are molecules designed to chelate (or bind) unwanted or excess metals found in a cleaning solution. These additives may be present in a cleaning solution to help remove unwanted metal ions from a surface – for example, hard water spots typically contain metal ions like calcium or magnesium. Sometimes, metal ions can interfere with a surfactant’s ability to clean, and the builder can help prevent this interference by chelating the metal ion.1 Although builders are often added to remove unwanted metal ions from the solution, they may have other affects on the solution (including pH).
These ingredients are added to improve the scent of the cleaner. Some components of the cleaner have an unpleasant scent. Adding a fragrance can improve the scent and thus the experience of using the cleaner. Fragrances are often made up from many different molecules. Many common cleaners will use essential oils to improve a product’s scent, while others may use artificial or synthetic flavoring agents, particularly in instances where natural production is not sustainable (e.g. vanillin for vanilla).2
It is important to note that unscented is not the same as fragrance-free.3 Unscented products may contain fragrance ingredients to mask or neutralize odors of the formula, while fragrance-free products contain no fragrance ingredients.3 The US EPA Safer Choice program has an additional Fragrance Free certification for products that meet the Safer Choice requirements and also have no fragrances.3
These ingredients are designed to prevent spoilage of the cleaning formula to extend the product’s shelf life and safety. Spoilage can be from bacterial or fungal contamination. Popular preservatives include sodium benzoate, phenoxyethanol, and isothiazolinones.
These ingredients are designed to either increase or decrease the pH (or acidity/basicity) of a cleaning formula. These ingredients are necessary as many cleaning applications require either an alkaline pH
(greater than 7) or an acidic pH (lower than 7) in order to work properly. Some cleaning solutions are around the neutral pH of 7.
Acids are used to lower the pH of a formula. Acidic pH cleaning solutions can often be used to clean or remove soap scum build-up. Eco-friendly household cleaning formulas may make use of citric acid to lower the pH of the formula. In an industrial setting, very acidic cleaners may be used to etch or clean metals. These formulas can be used to clean surface oxidation (like rust) from a metal’s surface to leave the metal looking shiny and new. Always read the label and use gloves when handling these products!
Bases are used to increase the pH of a formula. A few common bases used in household cleaners are sodium citrate and sodium or potassium carbonate. Degreasers, for example, often make use of a high pH in order to saponify (or break down) the grease molecules into components that are more soluble in a water-based cleaning product. Some specialty solutions can be rather alkaline – always read the label and use gloves when handling these products!
Sometimes, a weak acid like citric acid and a weak base like sodium citrate may be used together in a formula to make what is called a buffer. A buffer’s main function is to resist change in the formula’s pH to improve the formula’s shelf life.
2. Dignum, Mark J. W.; Josef Kerlera; Rob Verpoorte (2001). “Vanilla Production: Technological, Chemical, and Biosynthetic Aspects”. Food Reviews International. 17 (2): 119–120. doi:10.1081/FRI-100000269.
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