Time for a Change
The Sumo reusable nappy system (image: Valeria Mitelman, courtesy of Sumo).
Full disclosure: despite being the mother of two small humans, up until a few weeks ago, I’d never had anything to do with reusable nappies. This is not because I’m a rabid climate- change denier or any more ignorant of the pernicious legacy of single-use plastics than the next person. It’s simply that reusables have never really been on my radar as a serious for her master’s in product design at ECAL. When considering how she might apply SeaCell, an absorbent algae- and eucalyptus- based fabric she had been working on in conjunction with the Deutsche Institute für Textil- und Faserforschung (DITF), Kahlfeldt thought she might develop a mattress or period-proof pants. It was her tutor, Sebastian option. If anyone had asked me to consider adopting them as my daughters’ births approached, it would have seemed unthinkable and mildly masochistic – introducing yet another layer of complication and logistics into an already extremely challenging situation, all for the sake of an environmental benefit that was surely negligible when practically every other family seemed to be throwing nappies away. Oh shit, I thought, when the invitation arrived to trial a new reusable nappy with my three-month-old daughter Amelie for this article. Literally.
I’m not the only one surprised to find herself working with reusable nappies. Berlin- based designer Luisa Kahlfeldt was similarly blindsided when the possibility of creating one presented itself while she was studying Wrong, himself a parent, who steered her towards nappies instead.
“Initially it came from Sebastian and then I looked into it,” says Kahlfeldt, who found herself taken aback by some of the more garish, kitschy offerings on the market. “I was really fascinated. But I thought: container design. Why does this look like this? If you want something natural as a mother, you don’t want red polyester with, you know, angels printed across it. Maybe you want something that communicates that this has as much natural material as possible.”
Luisa Kahlfeldt and Caspar Böhme of Sumo (image: Volker Conradus, courtesy of Sumo).
Sustainability was another important consideration. In the UK, an estimated 3bn disposable nappies are thrown away every year and although parts of the Global South are far less-reliant on them, single-use nappies are used throughout the world. Given that even eco-friendly disposables, which often consist of no more than 60-80 per cent plant- based material, have been found to take 50 years to decompose, this is a big problem; the most plastic-heavy products, with their polyethylene waterproof back layers and polypropylene inner layers, could still be around in half a millennium. “The very first plastic nappy invented some time in the 50s is technically still rotting away in a landfill somewhere (and will continue to do so for another 430 years),” says Kahlfeldt. “And then think of all the babies in diapers that have been around since then! This very graspable image just stuck with me and made the whole problem so concrete.” What’s more, although numbers vary, even when you factor in the energy required for washing and drying them, reusables consistently come out on top: a 2023 report commissioned by the UK’s Department for Environment, Food and Rural Affairs (Defra) found reusable nappies to have 25 per cent less global heating potential compared with single-use nappies.
But it was another kind of global crisis that enabled Kahlfeldt to take her concept into the commercial arena. When the pandemic hit and she was furloughed from Konstantin Grcic Industrial Design, the possibility of founding her own company arose. This she did with creative director and cultural entrepreneur Caspar Böhme, setting up Sumo in 2020.
Sumo?
“The very first plastic nappy invented some time in the 50s is technically still rotting away in a landfill somewhere (and will continue to do so for another 430 years).”
“I didn’t really choose [the name],” says Kahlfeldt. “I guess because the corduroy-like material [of the nappy] looks a little bit like tatami [the material used to make traditional Japanese mats] and because of the tying [reminiscent of loincloth fastenings], a lot of parents were like, ‘Oh my God, my baby looks like a sumo [wrestler] wearing your diaper.’ And I thought it was a really catchy name. I am though very aware[...] of not wanting to appropriate any culture.” It’s for this reason, says Kahlfeldt, that the company steers clear of using sumo references in its marketing. “We try not to draw too many parallels. We would never, you know, have a sumo ring.”
Parental feedback has been a key part of the product’s development. Kahlfeldt has been keen to bring customers and potential collaborators with her on the journey, conscious of the fact that coming from an industrial design background makes the company something of an outlier in the baby-product market, where innovation is often driven by parents and carers identifying a need (Pampers itself proudly trumpets Viktor Mills’s development of the disposable nappy for his grandson in 1956 as its origin story). The Sumo website talks of its mission to develop products and services that elevate daily rituals and support the environment. “If you are a scientist, cloth diaper coach, parent, child, student, researcher, content creator, professor, policy maker, journalist, midwife, investor, designer, shop owner, or simply an enthusiast and want to join our quest, we would love to hear from you!” it reads. It’s an approach that seems to be working: not only has the company expanded to a team of four and garnered several awards – including the Techtextil Innovation Award for work in collaboration with Kelheim Fibres, and a Red Dot Design Award – but in July 2022 a Kickstarter campaign raised more than €23,000. This was enough to help the firm produce its first batch of 1,000 nappies, a sample of which Kahlfeldt sent me to try with Amelie.
The package arrived. Featuring one of Sumo’s Starter kits, it contained three medium- sized outer nappies with waterproof inner pouches, six absorbent inserts known as Ufos (apparently because that is what they look like), a roll of Dreamliner (a flushable insert meant to catch the “big business” produced by babies eating solid food), and Kahlfeldt had also thrown in an additional Schlepp bag that is designed to store soiled nappies before washing.
Schlepp, I thought grimly. Sounds about right.
The Sumo nappy, with its Ufo insert (image: Valeria Mitelman, courtesy of Sumo).
Still, there was no denying the beauty of the product. Beige with grey-green ties and edging (a colour that seems to have been supplanted by navy, brown and white in the company’s current offerings), the outer nappy was stylish and appealing – a world away from the gaudy, novelty-printed efforts Kahlfeldt encountered when she began her research. The outer shell’s zinc-treated blend of cotton and Lyocell – a textile made from bamboo or red birch used in place of the original SeaCell – felt beautifully soft and every bit as likely to reduce rashes and eczema as the marketing material promises. Meanwhile the waterproof pouch, made from a blend of Lyocell and Modal, gleamed like the inside of a shell. Even the thin waterproofing layer of polyurethane and the white plastic poppers at the hip creases – the product’s two non-sustainable elements – couldn’t spoil the nappy’s good looks.
The Ufo inserts were reassuringly sober too. Appearing more like heavy-duty sanitary towels than UFOs, they consisted of two linked beige pads lined with pure Lyocell, which Sumo claims can absorb moisture 50 times more effectively than cotton. Inside, layers of Galaxy and Bramante – trilobal and hollow-fibre cellulose fleeces developed with Kelheim Fibres and the Sächsische Textilforschungsinstitut – promised impressive wicking, absorption and retention. The idea that you might be able to reuse the outer nappies two or three times between washes and simply change the inserts seemed ingenious, and I was relieved that the accompanying booklet and single-page insert of dos and don’ts looked easy to follow.
“It is such a difficult task [to write instructions],” says Kahlfeldt. “On the one hand, I want to inform customers. But on the other hand, I want to create a product that’ll be like an Apple product, right? You open it and kind of intuitively know what you have to do.[...] I always find it very tricky to know what is too much information, almost a burden.”
And you do need to read the instructions because it turns out that the Sumo can’t be unboxed and used straight away. The outer nappy and inserts must all be prewashed three to five times.
Three to five times!?
“On the one hand, I want to inform customers. But on the other hand, I want to create a product that’ll be like an Apple product, right? You open it and kind of intuitively know what you have to do.”
It’s because of activating the cellulose in the absorbent core and removing the resins on the outer fabric, which would otherwise cause liquid to pearl and run off, Kahlfeldt explains in response to my incredulous email. One potential hack would be to soak the nappies overnight and then do one wash. This should ensure that the inserts are fully absorbent for the first use. Sumo has looked into prewashing the inserts as part of the production process at their manufacturer in Serbia, but the cost of this would make the retail price prohibitive. It was also for this reason that Sumo abandoned SeaCell, the algae-based fabric that was the original impetus for the project. “We are always on the lookout for sustainable algae- based fibres and fabrics with interesting properties,” says Kahlfeldt. “I do however have a much better understanding now of what parents expect in terms of performance and price point of diapers and baby hygiene products as a whole. I would say there is still much work to be done in the industry before we can offer a diaper made from algae that people can afford, or are willing to pay for.”
And the nappies are not exactly cheap now. The Starter Kit Kahlfeldt sent me retails at £168. Starter being the operative word, because, as any aficionado of the changing table knows, six nappies won’t get you far with a baby. My husband Steve and I are both veterans of the 10-poo change and, my friends, we are not alone. Assuming zero leakage, you would need at least double the number of inserts to be confident of getting through the day with a baby younger than a year. (Nighttime is a whole other question, requiring multiple inserts and layers; Sumo is currently developing a night nappy, but it is common for parents to use different brands during the hours of sleep.) And, when you consider the time needed for washing and drying, the numbers really start to rocket. Even with the inserts divided into linked pairs, it took 24 hours for them to dry on an indoor airer on a rainy day – for those living without access to outside drying space or with poor ventilation, this could prove particularly challenging (Sumo nappies can’t be tumble-dried as the heat might compromise the material). The All-In Kit that the company offers for £897 (reduced to £605 at the time of writing) comprises 12 outer nappies and 25 inserts, which would probably be just about enough to manage. Crucially, though, it only includes one Schlepp bag, meaning that you would need to purchase at least one more plus a wet bag for travelling, or else invest in a storage pail or two on top. Plus the nighttime nappies. And the energy costs for laundering. Given that the UK government’s MoneyHelper service puts the average overall cost of using own-brand disposables at £1,875 per child, Sumo may not save users much money in the long-run. The kits can be reused on younger siblings, of course, and selling nappies on after potty training offers the option to recoup some of the cost, but the initial outlay will prove too much for many.
Image: Valeria Mitelman, courtesy of Sumo.
To be fair to Sumo, it is not alone in this. Although its prices sit at the premium end of the market, reusable nappies are notorious for requiring a considerable upfront investment (MoneyHelper estimates an average of £300). In an effort to circumvent this barrier to entry, certain towns in Germany offer grants to help families afford the initial outlay, while in the UK some local authorities run reusable-nappy incentive schemes featuring vouchers and free tester kits. There are also nappy libraries, through which prospective users can lease different models in order to trial them ahead of purchase – a prudent move if you consider that, in Germany at least, 11 per cent of families try reusable nappies but only 7 per cent stick with them.
So how did we get on? Well, the nappies leaked. Not always and not, crucially, on the occasions when we had a code brown, but probably about half the times we tried them, making it impossible to reuse the outer diaper on more than a handful of occasions and also necessitating the additional washing of several mats and changes of clothes. By mid-afternoon on the first trial day, we had exhausted our supply of outer nappies. The problem was the fit. Although Amelie is well within the 4-11kg weight range suggested for the medium Sumo, and although we had the nappy on the smallest setting and did our best to tuck the edges into the skin folds as the instructions state, the leg holes weren’t as snug as they needed to be to keep the moisture in.
This, says Kahlfeldt, is feedback she hears regularly. The Sumo team is working to address this with its next prototype. However, the problem may not be purely a design issue: in the world of reusable nappies, it’s never a case of one size fits all. The variables are so fiendish that there are even tools, such as the questionnaire at thenappylady.co.uk, designed to help prospective users identify the products likely to suit them best, according to their child’s build and family’s lifestyle. You also have to factor in issues such as whether parents are devotees of Clean Cloth Nappies (which promotes particular sanitisation methods) or planning to practise elimination communication – the art of reading your baby’s signals that it is about to excrete and putting them on the potty from as near to birth as possible, a method that may sound daunting to many in the Global North but is common in other less industrialised cultures. So it’s conceivable that even with substantial reworking, the Sumo may never fit Amelie perfectly. She may be more of a Charlie Banana girl or a bumGenius or a wearer of Little Lovebum. Sumo, you see, does not have the monopoly on unusual names.
The Sumo office (image: Peter Oliver Wolff, courtesy of Sumo).
What surprised me, though, was that the leaks bothered me far less than I expected. This was in part due to the Schlepp bag, which, far from being hard work, proved a revelation. Lined with the same blend of Lyocell and Modal as the Sumo nappy’s waterproof pouch, it is designed to store soiled diapers for up to three days and then be chucked wholesale into the washing machine to emerge pristine along with its contents after a single prewash and wash. This it duly did, making the business of handling accidents pretty effortless. What’s more, when I wasn’t able to use Sumo, I found that I was far more conscious of how many changes I was doing and the number of nappies that I was throwing away.
Kahlfeldt says that this kind of increased mindfulness is a common result of engaging with reusables for parents and babies alike. Indeed, when it comes to children, a greater awareness of being wet (rather than the oblivion that can often follow from using disposables, with their chemically aided wicking that keeps moisture from the skin) can have the surprising bonus of making potty training easier and earlier. My limited survey of friends who had used cloth nappies bore this out, with several reporting that their children had spontaneously opted to start using the potty at relatively young ages.
Given that she’s not yet sitting up, it would have been a bit much to expect Amelie to wean herself off nappies by the time I had to write this article. Still, not jettisoning a soiled nappy at every change was very satisfying – so much so that I have found myself continuing to use Sumo when we have a stretch of time at home. Although this current iteration and fit would not be sufficiently reliable for us to consider using it out and about, it is reliable enough and the consequences of it failing are negligible enough to warrant keeping it in the mix.
“The reality is that most parents use a hybrid model. I don’t know a single cloth diaper mother who doesn’t have a pair of disposables in her handbag.”
This kind of approach, says Kahlfeldt, is becoming increasingly common. In recognition of this, Sumo even offers a Part-time Kit for £237, aimed at families keen to mix and match. Indeed, with many health-professionals recommending that reusables only be used once the umbilical stump has detached five days or so after birth, and NHS advice being that soiled diapers should be discarded outside the home for a week after babies receive the live rotavirus vaccine at eight and twelve weeks, it is technically impossible for anyone keen to adhere to medical guidelines to use washable nappies exclusively. “The reality is that most parents use a hybrid model,” says Kahlfeldt. “I don’t know a single cloth diaper mother who doesn’t have a pair of disposables in her handbag.”
Because, although nappy-changing is a shared enterprise chez Amelie, it is still mothers doing the majority of nappy changes and associated chores. A 2020 study by the Resolution Foundation found that while men in the UK put in an average of 16 hours a week of unpaid domestic labour, women clock up 29 hours in the same period. As a result, any products that increase the workload associated with childrearing or tie the primary carer more closely to the home inevitably risk setting back gender equality. But if Sumo is successful in helping to normalise a hybrid approach, with parents opting for the greener option when circumstances allow and then bringing out disposables when logistically necessary, it’s conceivable that more people might at least try them. Such perceived flexibility would also reduce the initial expense, opening up reusables to lower-income households. And while this wouldn’t eliminate the issue of single-use nappies mouldering in landfill for centuries to come, it might begin to reduce the 5,000 soiled disposables that each UK baby is estimated to generate. That, surely, is good design in the broadest sense.
It has certainly shifted the dial on our thinking. Preparing to go on a family holiday last week, I found myself eschewing the disposable swim nappies that I would normally purchase in favour of a reusable pair. “One plastic bottle is saved from landfill with each TotsBots Swim Pant,” reads the product’s label. A drop in the ocean in the face of the 10,000 or so disposable nappies that may prove to be my longest-standing legacy, but maybe that’s how lasting change starts.
Words Ann Morgan
This article was originally published in Design Reviewed #22. To buy the issue, or subscribe to the journal, please visit the online shop.