More and more things in my house seem to be made from microfibres—my steam mop, my computer screen cloth and my dog mat. This got me wondering, what is microfibre and how does it work?
In my research, I found that a microfibre is made from thin (less than 1/100th the width of a human hair) synthetic threads, less than 1 or 1.3 denier. This means that 9,000m of it would weigh only 1.3g, which is about the same as silk. Apparently, denier describes the thickness of stockings, but I have never been in the market for stockings, so this was news to me.
Thin synthetic strands of microfibre were first developed in the 1950s, but they were uneven and not very useful. By the 1970s, two Japanese scientists, Miyoshi Okamoto and Toyohiko Hikota, figured out how to produce a continuous filament, which allowed for more practical applications. In the 1980s, the microfibre textile, Ultrasuede was introduced—this synthetic material feels like soft suede, because of the fineness of the strands. In Sweden, during the 1990s, microfibre products were common in household cleaning. In the 2000s, the material became widely available in North America. The sporting goods industry even tried to make basketballs with it, but that didn't work out so well.
Microfibre is defined more by its dimensions than its composition, but usually it is made from polyester and some kind of polyamide, like nylon. Polyester tends to attract oily things, like fingerprints on your glasses. Polyamides attract watery materials. Together, the two can attract many kinds of messes without detergents or other cleaners. Small scale attraction between tiny particles and the microfibre threads involves van der Waals forces, which may also help to explain how the toes of geckos stick to things. For cleaning purposes, the strands also get treated with chemical and physical processes to split them up. Split ends might not be good for hair, at least in shampoo commercials, but for cleaning materials, they increase the effective surface area for collecting stuff you do not want, in tiny nooks and crannies, including bacteria. The small gaps in the strands allow for water to be drawn up by capillary action.
Because microfibre cloths are good at picking up dirt, getting rid of that dirt is something to consider. You can scrub the cloths by hand or clean them in a washing machine and apparently the cloths are good for hundreds of runs. But if you throw them in with other materials that produce a lot of lint, the lint will clog up the micofibres. Too much fabric softener can also plug up the crevices. You also don’t want to use acids, bleaches or a lot of heat with them, because they might dissolve or melt. Microfibre products can air dry fairly quickly, because there is not a strong bond between the water and the fibres.
Microfibre cleaning materials are often promoted as being environmentally friendly, because you don’t need to use detergents with them. But they are made from petrochemicals (although some can be made by recycling pop bottles), so the end product is not recyclable, because it uses different kinds of materials. But if you take care of the microfibre cleaning products properly, you can reuse them hundreds of times, so that seems reasonable. If you have any insights to share on the science of microfibre let us know.