In plastic soap dispensers, bacteria can grow in the micro cracks in the plastic. In fact, there have already been recalls of liquid soap dispensers from large manufacturers because of contamination with Enterobacter gergoviae bacteria. However, bacteria and germs have no chance on the alkaline surface of a solid bar of soap. They are germ-free even without preservatives.
Other aspects that speak for solid bar soap
- Economics Solid bar soaps are much more economical than liquid detergents. The price of solid natural soaps may seem high compared to a discount liquid soap – but the bar soap lasts twice or even three times longer. In addition, solid bar soap is not as easy to overuse, whereas too much liquid soap is often used, with an excessive amount running straight down the drain.
- Lipid-replenishing Solid soaps are moisturizing (lipid-replenishing) and mostly have a superfatting of 6-10% (shampoos have a slightly smaller percentage). In soap making, some kind of fat, such as olive oil, combines with sodium hydroxide to make soap. If there is more fat than sodium hydroxide, the soap is said to be superfatted. On the other hand, liquid detergents with surfactants often feel hydrating, rich and moisturizing, but the synthetically produced detergents remove valuable oils from the skin. Manufacturers attempt to prevent the skin from drying out by adding rehydrating substances to liquid soaps, but the additives are also largely washed away with the rinse water.
- Environmentally friendly Solid soaps are a natural product and are often made from purely plant-based raw materials without synthetic additives. Furthermore, they are often packed in compostable film or paper–so there is hardly any packaging waste. In contrast, a plastic bottle (or glass bottle with plastic pump) is always necessary for liquid soap, and preservatives are added.
- More readily biodegradable Solid bar soap is more readily biodegradable than most synthetic surfactants. If solid soap gets into the wastewater, it forms what is called lime soap and fatty acids through reactions with existing salts and acids. Both are insoluble and not surface-active. Later, microorganisms living in the wastewater decompose the solid soap into carbonic acid and sodium hydrogen carbonate. The fatty substances, such as those found in solid soap and lime soap, are also components of living cells and metabolic products of the microorganisms that are active during degradation. They are considered to have no negative effects on wastewater and groundwater.
- Shapely Solid bar soaps are more individual, express their own character, feel good in your hand and have a more attractive appearance than a plastic bottle.