Whether solid, liquid, or something in-between, everyone has very regular interactions with soap. The variation of facial soaps and cleansers that are tried, analysed and researched in the quest for clear skin can become intensive. But, what of the humbler hand-wash or shower gel?
In new research published by Kantar Worldpanel’s strategic insight director, Tim Nancholas, sales of barred soap have risen three per cent from September 2017 to 2018. Many speculate that this is from an increase in the awareness of plastic waste. However, the source of this change in buying habits is unlikely to have all come from the consumer. If the more luxury-friendly products did not exist, it is unlikely that buyers would be willing to wash their entire bodies with a bar of Imperial Leather.
In truth, many brands have become aware of the push to produce eco-friendlier, reduced-plastic products. Luxury brands such as Jo Malone and even Chanel have launched ranges of bath soaps and solid bars. Lush has been leading producer of eco- friendly soap products on the high street, bringing out products ranging from solid shampoos to bath bars to solid moisturisers. This allows for the changes in buying habits and the increase in solid soap sales.
The question then becomes: which is actually better?
To give a basis in chemistry, true soaps that would sit in a bathroom are known in the industry as ‘toilet soaps’. These are the salts of fatty acids, the source of which could be animal or vegetable oils or fats. Historically, whale fat was used but today, beef is a more likely source. Vegetarian sources range from aloe vera to coconut to palm oil.
Many of the choices that sit in the soap aisles, however, are not actually soap at all. Instead, they are synthetic detergent. They work very similarly but with a different manufacturing process.
When you use soap, the particles and grime are solubilised, separating it from the skin. The fat/oil molecules that need to be washed away are associated with ‘micelles’ which are tiny spheres of soap molecules. These micelles have fat-attracting pockets on the inside which pick up the fat and oil, making them soluble enough to be washed away. In this respect, solid and liquid soaps are very similar.
The differences between solid and liquid soap become stark when their ecological impact is compared. In a cradle-to-grave life-cycle analysis, scientists at the Swiss Federal Institute of Technology in Zurich found that per application or per wash basis, the carbon footprint of liquid soap is about 25 per cent larger than bar soap. Additionally, we tend to use seven times more liquid soap than bar soap per usage. In the environmental consideration, solid soap clearly wins out.
Finally, what is the difference in actual cleaning? When liquid soap became popular in the 1990s, the idea that it was a ‘cleaner’ versionof its solid counterpart was firmlybelieved. This claim, however, follows in the long list of concepts that caused media sensation and then turned out to be false, without nearly as much fanfare.
As early as 1988, scientific paperswere published that demonstrated there was zero difference in cleanliness between solid and liquid soap users. The solid soap had no more bacteria than the liquid and was just as ‘clean.’
Overall, there appears to be very little difference between solid and liquid soaps, as far as cleaning method and ability go. The difference comes from the environmental and ecological impact. And, as society becomes more aware of environmental issues that are becoming ever more pressing, the trend of buying solid soap is likely to continue, if not increase.
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