Polyurethane soles are prone to disintegrate if the shoes are not worn regularly  all year round.

Who’d have thought it? Some shoes – the more expensive ones, of course – need constant wearing in order to prolong their life.

Put them in your cupboard for months on end, and the first time you wear them, the sole could literally disintegrate as you walk.

I first heard of this in 2009 when a Cape Town reader complained of a pair of Hotter shoes (a UK “comfort” brand) falling apart.

Despite the fact they were a year old, she’d bought them the previous winter and stored them in her cupboard during the summer, unworn.

The shoes had a moulded polyurethane (PU) sole, which, while being light and comfortable, is prone to a form of deterioration called “hydrolysis”, especially in coastal, humid areas, when not worn. In short, they crumble into a sticky mess.

It seems the act of wearing them puts pressure on the soles and squeezes out the moisture, which would otherwise insidiously break apart the foam-like structure. So it’s possible for a pair of unworn or barely worn shoes to disintegrate.

As I discovered when I Googled the words “PU soles” and “disintegrate”, this is a hot issue, and affects most brands of “comfort” shoes, among them Clarks, Hush Puppies, Green Cross, Scholl, Bass and Ecco.

Given that these shoes are not cheap, those who invest in them expect them to last many seasons.

Unbeknown to them, the normal habit of not wearing summer sandals in winter, or boots in summer, means these shoes are unlikely to last more than a few seasons.

The thing is, the manufacturers and retailers haven’t been warning buyers of PU-soled shoes that unless they are worn regularly throughout the year, they could fall apart prematurely.

I recently investigated a case of a four-year-old pair of Froggie shoes falling apart – not from overwear, but lack of wear.

When Iris Harwood of Stellenbosch complained to Froggie in December that her sandals had fallen part, she got the following response: “This style is about four years old and we no longer carry those units in stock. Unfortunately there is nothing that we can do.”

Naturally, she wasn’t happy.

“Unsatisfactory reply,” she responded. “No matter how old the style is, the disintegration of the shoe is totally unacceptable. Your shoes are not cheap at all, and one does not expect them to disintegrate, even after four years.”

When no further response was forthcoming, Harwood contacted Consumer Alert.

Remembering the Hotter case, I asked Froggie why the company had not explained to Iris, in its response, how PU soles were prone to hydrolysis – to avoid this happening to her again – and why those customers currently buying PU soles are not warned not to store their shoes for long periods.

To cut a long story short, Froggie has since refunded Harwood, and the company has had swing tags printed advising consumers who buy PU-soled shoes how to prevent the soles from disintegrating. The company hopes to have them in its stores during the course of this month.

To my mind, it’s vital that consumers be warned about this, especially given the Consumer Protection Act only provides an automatic warranty on products for six months, and these shoes take longer than that to fall apart, if not worn.

Will other manufacturers follow Froggie’s lead?

I asked one, who asked not to be named, before saying that he was not aware of any shoes in the world with PU soles “which had a warning attached to them”.

“Most cases occur in areas like KZN, where the shoes have been left for years in a box,” he said.

“It really depends on the quality of the PU, how old the shoes are and how they are stored. In essence, each case is different and cannot be generalised.”

Bottom line: the average consumer would expect shoes they wear often and walk kilometres in to show signs of wear in the sole. But they wouldn’t expect shoes to be destroyed by leaving them unworn in a box or cupboard for months.

Which is why they need to be told this.

Spread the word!