Eli5: why do shoes disintegrate when left unworn (for extended period of time) and frequently wearing them actually prevents/delays disintegration?


Eli5: why do shoes disintegrate when left unworn (for extended period of time) and frequently wearing them actually prevents/delays disintegration?

In: Other

I am assuming you are talking about leather shoes.

The leather is a natural product, with time the atmosphere dries the leather out slowly (imagine like a piece of bread left on a counter top). The loss of moisture hardens the leather. When you use the shoes, you sweat into the them, this replaces some of the moisture, this is also why you should be polishing your shoes regularly. The polish helps to protect the leather with wax and other products to keep it in a good condition and supple.

For the soles decomposing, it’s not so much being unworn that deteriorates them as time. The soles are sometimes made from crappy plastics that degrade

Saltwater is a natural preservative. When you don’t wear your shoes, they oxidize – a layer of deterioration forms and expands on surfaces, including the soles. Similar to rust, if the rust isn’t removed, the metal is consumed. By wearing your shoes, oxidation is removed by friction and the sweat keeps the material supple.

Yep. Happened to me. Not “cheap” shoes. Nikes. Sat in the laundry room all winter. Tried to put them on in the spring and they fell apart, as if their glue had stopped working.

As someone who walks just about everywhere and forever having standing jobs, this is not the case for me. That and I’m heavy on the heel when walking, so destroy soles and the heel is the first part to be grinded to nothing. But I also only own maybe 2-4 pairs of shoes at a given time and never expensive ones so that probably doesn’t help.

It’s just like dry rot from a tire. It’s not the use or lack of that causes damage, its mainly what happens between these periods. if kept in a climate controlled environment it will easily last years. I still wear shoes from high school and that was 2010

Thats a great question! I recently bought some booties on Posh app (they were brand new, never worn -forgotten in someones closet , i assume!) then when i wore them for the first time , the inside lining pretty much fell apart all over my socks! Ugh (cant tell anything wrong from the outside , but bcuz they were a lil too narrow on my wide toe base-was considering re-poshing them!) prolly cant now bcuz of it! Guess i will try and stretch them out , super cute!

I assume you’re talking about the soles falling off of running shoes.

The synthetic materials used to bond the sole to the boot simply degrade and fall apart over time.

This happened to my girlfriend last month. Put on a pair of shoes that she hadn’t worn in years. We got in the car and went to the grocery store. At about aisle 2 I noticed some weird stuff on the floor. I thought to myself “damn this place cant even keep their floors clean”. Two aisles later she notices a trail of crumbled rubber following her around. By the time we left the rubber had fallen off and she shuffled to the car thoroughly embarrassed.

Ooh, I know this one (having had a head office job at a shoe company)!

This is due to hydrolysis in Polyurethane outsoles!

PU is made of specific molecules, a bit like making something out of Lego, but each building block is made of a bunch of individual Lego bricks. Water likes to steal atoms from the PU molecules, a bit like one of your friends coming over and taking every fifth Lego brick from something you’ve built. When enough bricks are stolen by your friend the structure falls apart. This is what happens in hydrolysis – water reacts with the polymers and breaks down the complex molecule.

This is a common issue with certain materials used in shoe soles. The material will break down suddenly. I have had this occur with multiple shoes in the last few years. It is not caused by storage or use, it just is the nature of the material used and its inherent instability and random time to breakdown.


I doubt it actually does delay disintegration, you just wear them out usefully before the materials themselves fail, as opposed to not using them and the materials failing in a similar timestamp.

I’ve noticed that Blundstone’s boots have this problem. If used fairly regularly, they just last and last. but if left alone for a couple years the rubber/PU sole ends up crumbling off of the upper.

I went to a shoe repair shop, and was told that the nature of these soles they can’t repair them, even though the leather upper was still in mint condition. He said that, when stored, the oils in the sole end up leaching out, but with regular use the oils get redistributed in the rubber.