Could You Be Using Wool To Prevent Toe Blisters?
Wool is a popular blister prevention product for toe blisters. It’s used mostly in the hiking community, particularly in Australia and New Zealand. So, let’s see what it has to offer. Sincere thanks goes to Jim for his help with this post. Jim is a long distance runner from Florida who wanted to try wool for the first time for toe blisters. He was kind enough to share his experience every step of the way.
Different types of wool
Wools are classified by the diameter of their fibres and the unit of measure is the micron. We're going to be looking at wool from 19 microns to 37 microns. Compare that to a human hair which comes in at around 100 microns. The smaller the micron, the softer the wool. Different sheep breeds produce wool of different microns.
How wool prevents blisters
I’m not aware of any research on wool and blisters, and I haven’t used it extensively myself. I’ve had a fair bit to do with wool though, as the daughter of a sheep farmer.
Let me come clean right now - I'm not entirely sure how to describe the way wool prevents blisters. That's the biggest reason why I haven't covered it yet on my blog. I do have some thoughts though.
Wool: Potential mechanisms of action
Could wool work by one or more of the following 5 mechanisms of action:
- Does wool reduce friction levels at the skin surface (skin-wool interface) thanks to the greasy lubrication of lanolin? If so, does this degrade over time as per the Nacht et al findings on greasy skin lubrication?
- Does wool reduce friction levels at the skin surface (skin-wool interface) by promoting dry skin? Conceivably it does thanks to lanolin, the natural oil in wool. But what about when it's been washed like some commercially-available wool are? Could you call wool moisture-wicking? What happens in waterlogging situations?
- Conceivably, the wool-wool interface coefficient of friction (COF) is lower than the clammy skin-sock and skin-skin interfaces. But how much do wool fibres glide over one another in a single application (card) of wool - do they glide independently? What I mean to say is, can wool be described as a material with a low shear modulus, much like the gel of gel toe sleeves? In this way, the material itself (fibre on fibre) deforms to shear stress leaving the skin to undergo less shear deformation.
- Or do you need two separate applications of wool on the blister-prone part to achieve this easy movement to reduce shear stresses in the skin? Much like the mechanism of action of double socks?
- Simple cushioning over bony prominences.
If there are any materials scientists out there reading this, I welcome your comments!
Does it stay put?
One would think that because there’s nothing adhering the wool in place, it would move around and end up at the end of your sock or under your arch. This tends not to happen though. Take a look at Jim’s photos – the wool is melding with his wool socks and the cocoon it creates around the toes is even maintained if you remove it carefully. There's a short video later on that shows just how strongly the wool becomes at one with the sock.
Take a look at the 15 sec video below as Jim takes his socks off. This is a synthetic Rockay running sock, though this is representative of what happens with wool socks too.
Jim's experience with wools of different microns
The 25 micron wool Jim used above is called Wuru Wool. It's a New Zealand sourced Merino wool available in the USA, including on Amazon. Jim is a runner from Florida who racks up a lot of miles and needs pinch blister prevention for his pinky toes on pretty much every run. So he was going through a lot of wool. Once he found the 25 micron wool was working, he looked around to see if he could get larger quantities without breaking the budget. In Jim's words, the Wuru Wool "is as beautiful as it is expensive."
He got onto Sharon from Feltrite on Etsy who sent him both 19 micron and 21 micron Merino wools. He preferred the 25 micron from Wuru.
Later, he tried a 29-31 micron wool from Shetland sheep from Paradise Fibers. And then a 33-37 micron wool from Romney sheep from Wool-it. He couldn't notice a difference between the two new wools, or a difference between these and the 25 micron Wuru Wool. But he had started running longer distances.
So Jim's favoured wool for preventing the pinky toe pinch blister he suffers most commonly with is 25 microns or greater.
More on wool microns
Sally from Trekkers Wool in Victoria advised they use a 19 micron wool:
“Our micron sits around the 19 mark. Merino wool generally doesn’t go higher than 22, so the 25 micron would be a different sheep breed. Interesting that the higher micron is thought to provide better protection. We have cross bred ewes for fat lambs and their wool would sit at the 23-24 micron mark. It’s a lot harsher and is generally used for carpets.”
Lynda from Hikers Wool in New Zealand uses wool over 25 microns:
"We use a bigger micron, over 25, in our wool for the best protection to our customers. We don't use Merino as that fibre is too soft to achieve the required result for our Hikers Wool product."
Katey from Wool-it in New Zealand use wool from Romney sheep that comes in at 33-37 microns:
“The Wool-it product is in the range of 33 to 37 microns. Initial experimenting with lower micron (eg: Merino around 25-29 microns) didn't offer as much resilience. The finer wools are beautifully soft but as a consequence they don't have the same 'bounce factor' and therefore the ability to reduce pressure is less effective. We found we needed to use a much greater volume of the finer wools to get the same effect and that volume meant that the wool bundle could sometimes be felt as a 'small lump' in the sock.”
"Carding" is the process of untangling and mixing fibres to produce a continuous sliver of wool. It breaks up any disorganised clumps of wool and then aligns the individual fibres to be parallel with each other.
Lynda from Hikers Wool provided this little snippet of very useful information about how their wool is card to make it different to others:
"Hikerswool is not a single card sliver with all the fibres running the same way. It is twice carded in such a manner that the fibres are 'crosshatched' making the product much stronger. For example, if you place a piece of Hikerswool over the whole toe area it is sturdy enough for the toes not to poke through."
I wonder whether, as well as making the wool sample more sturdy, does a double-carded wool sample give an additional frictional interface, or an additional opportunity for there to be shear absorption (mechanisms of action 3 and 4) compared to wool that has been carded once?
Is wool oily or greasy?
Lanolin is the oil or grease in sheeps wool. The wool used to make clothing has been vigorously cleaned and surely wouldn't contain much natural lanolin. Let's face it, you don't really want your merino under-garments to make you smell like a sheep. However, wool sold for the purposes of blister prevention is sold as sections of fleece (and it probably doesn't matter if your feet smell a bit like sheep). Depending on how processed it is, blister prevention wool can be anything from cleaned, to a raw state with as much lanolin as it had straight off the sheeps back. Katey from Wool-it provided some helpful clarification. The first quote below is from the Wool-it website, and the following one is from our email conversation.
“At the mill the wool is scoured (washed) using a standard aqueous treatment with an Eco-friendly detergent that is bio-degradable, dried and carded into slivers. …with the naturally rich lanolin content from the wool fiber.” Wool-it
“With respect to the lanolin content, absolutely the process of scouring and washing reduces the amount of natural lanolin, a small amount is returned to the product at the end of the process and I can certainly vouch for having very soft hands after an hour of hand packing Wool-it!” Katey, Wool-it
On the other hand, Trekkers Wool mention theirs is unprocessed. I sought clarification and Sally confirms their wool is unwashed so the lanolin isn’t removed and added back in later. She even sent a sample pack. I can vouch for the clean fleece and lovely shearing shed aroma I remember so fondly from my childhood. Sally said:
“The only cleaning involves trimming away the dirty tips and removing seeds which is done by hand. This is the only way we can keep the lanolin intact.” Sally, Trekkers Wool
And somewhere in between is Hikers Wool. Lynda said:
"We don't add lanolin back to the wool but our wool is only lightly washed so there is still lanolin left in it. We pack our wool by hand so any remaining vegetable matter (e.g. seeds) are able to be removed then." Lynda, Hikers Wool
How do you use wool to protect you from blisters?
Here’s what Wool-it says:
- Tease fleece out with your fingers to aerate and add resilience
- Pad around the area as required or ‘pack’ between toes.
- Avoid wrapping/winding around toes as fleece felts and fibre tightens with movement
- Fleece pad is sometimes re-useable depending on your comfort level
How much wool do you use?
It depends, but possibly a bit more than you first think. It really packs down once your sock and boot is on and you’ve walked for a while. You can stop and add more if you need to. Take a look at this Hikers Wool video for a demonstration.
Can you reuse wool?
Jim asked this very question of Sharon from Feltrite. Here's what she said:
"The problem with recycling the wool is that sweat or water combined with friction will cause the wool to felt, clump, as the scales on the fiber open up and tangle with each other." Sharon from Feltrite
Jim's experience with wool for blister prevention in running
Here's what Jim has learned so far about wool for his feet, blister issues and long distance running:
- Larger microns are better - at least for the products I have tried so far.
- The wool from Feltrite gets smelly if left sealed. It is also slightly darker, I am guessing a less stringent cleaning process. [Note: The review comments on this 19 micron wool is that it is whiter than most (presumably very cleaned)??].
- Don't try to wash it and reuse it.
- The best way to use wool is to pull lengthwise along the "grain" of the rove at the desired width, then cut for length.
- The more the better.
- While the wool does constrict, I have yet to find it uncomfortable while running.
- It is difficult to remove the wool from socks, independent of micron size.
What I love about wool
I really like the fact that the toes can glide against one another without the blister-causing shear, without the addition of too much bulk, like gel toe caps or toe-socks. So I love it for blisters between the toes. I’m pleasantly surprised at how well wool has worked with Jim's pinch blister. Although, he is yet to test it on some really big distances and endurance situations, so I'm looking forward to seeing how that pans out. But true interdigital blisters will surely benefit from wool as a prevention strategy. As will blisters on the tops of the toes, where the toes aren’t too hammered or bent.
More than anything, I love that if the wool fails to help, and you do get a blister, it’s an easy transition to using adhesive dressings (island dressings, hydrocolloid plasters) in your blister treatment. Other friction-management prevention products like lubricants and powders will retard the adhesion of dressings and make effective blister treatment very tricky. This won’t be a problem when you remove the wool. You can even use wool again after you apply a dressing, to reinstate some sort of friction management (important) without the threat of the dressing sliding off (like it would using a lubricant).
It’s also compact and light, so it really suits hikers carrying a pack and as an addition to any blister kit.
Wool is non-sterile and not suitable on broken skin and open wounds. It’s also unlikely to help enough with significant toe deformities like rigid hammertoes and claw toes.
Wool is something worth considering as an addition to your blister kit. Use it to prevent toe blisters. And use it as one of the only practical friction-management strategies for toe blisters when you also have a dressing in place.