It's the classic dilemma: Hikers want boots that resist water and don't get wet in rainy and watery conditions.
But they also want hiking boots that are breathable and allow internal moisture to ventilate in order to keep their feet dry. Is it possible to have both? Can you have hiking boots that are waterproof and breathable?
Breathability of Hiking Boots
The first question is whether your hiking boots are breathable to begin with, and that depends on what the upper part of the boot is made of.
There are a wide range of fabric hiking boots, often incorporating panels of mesh. Fabric hiking boots are the most breathable, but, because fabric is naturally porous, they are the least water-resistant.
Many hiking boots use synthetic materials like nylon, and/or plastics like PVC. These materials are naturally water-resistant, but not breathable.
Leather is extremely common in hiking boots, because it is so durable.
Leather in boots is either split-grain (made from the inner layer of the hide), top-grain (made from the outer layer of the hide), or full-grain (made from the full thickness of the hide). Leather naturally has both some degree of waterproofing, and some degree of breathability, depending on the thickness and quality of the leather.
Waterproofing of Hiking Boots
Most plastic and synthetics materials are inherently waterproof, unless they have been manually permeated (as in a nylon mesh). Natural materials need to be treated to resist water, and there are several ways to achieve waterproofing in hiking boots.
Wax was once the most popular way to care for leather, although it is less popular now because it is time-consuming.
However, waxing leather is a great way to keep it conditioned, and to maintain both the water resistance and breathability that leather naturally has.
Wax is also used to waterproof natural fabrics like cotton and canvas to resist water without compromising ventilation.
The reason wax works so well is because it coats the fibers of a material, preventing them from absorbing water, but it does not block the tiny openings in the material that allow air to circulate.
There is a huge range of different spray-on waterproofing treatments, suitable for different materials, and with different degrees of waterproofness and breathability.
Sprays are most commonly used on fabrics, and are usually not very durable, and need to be frequently re-applied. When the spray loses effectiveness, the fibers in fabrics absorb water and get larger, closing the openings that also allow breathability.
In other words, when the spray breaks down and loses effectiveness, both water-resistance and ventilation are compromised at the same time.
Oils and creams
As with sprays, there are a huge range of different oils (most often used on leather) and creams (used on all kinds of materials).
Many of these products are specifically designed to add water-resistance while protecting breathability, but some, either because of the formula or the way it is applied, will clog and block openings that provide ventilation.
Overall, it really depends on the specific product and the kind of hiking boot that the cream or oil being used on.
Today, more and more hiking boots are being made with an inner liner that adds waterproofing without compromising breathability.
These liners are usually designed to work along with the material of the entire hiking boot, as a complement and backup to the exterior waterproofing.
In fact, you should never rely exclusively on an internal waterproof membrane to protect a hiking boot, because if the upper material absorbs water, the boot becomes wet, heavy, and less breathable, even if your feet remain dry inside.
Are Waterproof Hiking Boots Breathable?
Because of the many factors above, there isn't a clear-cut answer. Waterproof hiking boots can be breathable, if they are made of the right materials and the waterproof coating is maintained properly.
However, as a general rule, waterproof hiking boots are less breathable than non-waterproof hiking boots. That's because, when we talk about breathability and ventilation, we aren't really talking about exchanging air, we're talking about exchanging moisture.
When a person wants a boot to be breathable, what they generally want is for heat and moisture created by the feet to naturally dissipate, keeping the inside of the shoe cool and dry.
All waterproofing methods naturally create some degree of a moisture barrier that keeps sweat inside the shoe and doesn't allow it to escape.
For the most efficient ventilation and cooling of the inside of a hiking boot, the outside shouldn't be waterproof.