1. A Student Experiment Shows New Towels Absorb the Least Water
In a student experiment, new towels and those washed 3, 5, 7, and 9 times were dipped in colored water. The new towels absorbed the least, while those washed 7 times absorbed the most. There was little difference between 7 and 9 washes [3]. However, this result came from one student testing one towel, so it does not mean 7 washes is a universal rule.
Why do new towels resist water? An expert at RMIT University in Australia explains that new fabric is often coated with silicone-based finishes to make it soft and prevent wrinkles. These finishes can repel water. Repeated washing and drying create tiny surface damages, increasing roughness and improving absorption [4]. Note that this explanation refers to tea towels, so it may not apply exactly to Japanese towels.
Does the cotton material itself repel water?
2. Natural Cotton Contains Impurities That Repel Water
According to a report from the Osaka Prefectural Institute of Industrial Science and Technology, natural cotton contains cellulose along with impurities like pectin, wax, and fat. To make cotton absorbent, these non-cellulose impurities must be removed. This process is called scouring. For towels, this is generally done using alkaline treatment [1]. So, for cotton fabric to absorb water, removing these water-repelling components is essential. A towel that was not scoured sufficiently can end up with low absorbency.
The same report notes that removing impurities improves absorbency but tends to make the fibers "harder." This is because the removed components also helped fibers slide against each other [1]. The English abstract of a later report from the same institute also says that removing oils from woven towels usually raises absorbency but lowers softness [2]. In the conditions of this report, increasing absorbency tended to decrease softness. Absorbency and softness can be difficult to balance. "Soft towels absorb well" is not always true. How do fabric softeners, used to improve texture, affect absorption?
3. Does Using Fabric Softener Reduce a Towel's Absorbency?
Kao’s Q&A explains that using too much fabric softener can cause ingredients to build up on clothes, making them repel water and changing their texture. This can reduce the absorbency of towels and underwear. If this happens, they suggest temporarily stopping use and washing with detergent to remove the buildup [5]. The conditions specified are "overuse" and "continuous use."
On the other hand, a test by the Fukui Prefectural Consumer Life Center answers a different question. They washed new face towels with water only, then treated them with 9 brands of fabric softener at the labeled amount and 3 times that amount, once each. They measured the time it took for the towels to sink in water. For 6 of the 9 brands, the difference between the two amounts was slight, with no clear change based on usage amount [6].
This test measured the effect of a single treatment, not the buildup from continuous use. It does not contradict Kao’s explanation; they are measuring different things. The same report also found large differences between brands, even at the labeled amount.
4. Towels from Different Brands Take Very Different Times to Sink
In another table from the same report, even when treated with the labeled amount, the time it took for towels to sink varied greatly by brand. One brand sank in about 7 seconds, while another had more than half of the towel still floating after 10 minutes [6]. Since 10 minutes is 600 seconds, this is more than 80 times longer than 7 seconds.
One important point: towels washed with water only also did not sink after 10 minutes [6]. The reason for floating cannot be blamed solely on fabric softener. This was a single test, and brand names were kept secret. How can we measure "absorbs well" or "doesn't absorb well" with numbers instead of feelings?
5. How Towel Absorbency Is Measured with Numbers
The Osaka Prefectural Institute of Industrial Science and Technology describes how to measure towel absorbency. The JIS L 1907 surface absorption method (modified Laroze method) measures the speed and amount of water absorbed by a 60 mm circular towel piece from below. The "absorbency index" is calculated from the speed V and the amount W as 2545V + 1411W + 79. The standard for hair-drying towels is 800. In an experiment, high-absorbency towels scored 851, while low-absorbency towels scored 119 [7].
In this study, high- and low-absorbency towels were made using the same cotton yarn, weave density, and weave structure, varying only the degree of scouring. When wiping up 1 ml of water droplets, high-absorbency towels removed 100%, while low-absorbency towels removed 50–60%. Assuming a changing room at 5°C, tests with 9 adult men showed that skin temperature immediately after wiping was about 0.5°C lower with low-absorbency towels than with high-absorbency ones [7].
This 0.5°C difference is specific to the conditions of this experiment. It cannot be linked to causes of colds. The reasons towels do not absorb water likely involve a combination of new finishes, cotton components, and softener buildup.
6. A Simple Way to Compare a New Towel and a Used Towel Yourself
If you want to investigate, try this: Place the same amount of water on the corner of a new towel and a well-used towel. Compare the time it takes for the water to soak in using a clock. Use a dropper or spoon to ensure the water amount is the same.
Official information: Reports and technical sheets from the Osaka Prefectural Institute of Industrial Science and Technology cover towel scouring and absorbency evaluation. The Fukui Prefectural Consumer Life Center’s test purchase report includes tables on fabric softener absorbency tests.