We wanted to address, in a single protip, the major aspects of waterproofing you'll likely encounter. The goal is to help you understand the different technologies of waterproofing, how different types of gear or clothes are made waterproof, and then how to keep dry!
If there is one thing you really must read here, it's the section on The Water Within. So often, a reason we get wet outdoors (or at least have that clammy feeling) is due not to external rain but to internal sweat unable to escape. A big difference between new outdoors adventurers and more experienced folks is how to ensure condensation is well-managed!
Electronics & hard cases
For many folks, GoPros, navigation devices, and cameras totally count as gear! They may also have waterproof hard plastic cases (again those camera housing for underwater adventures) as opposed to soft, fabric-based dry bags. That said, in industry terms, this is less outdoor gear & clothing; we don't carry much of it (the overlap would be headlamps and lanterns that we do carry). The technology behind waterproofing is very different than for fabrics, focused on construction (e.g., how electronics are sealed); there are entirely new terms (e.g., weatherproof versus submersibility) and new concerns (e.g., corrosion, which could be analogous to mold in its destructive nature!). Therefore, this category of products is out of scope for this protip. One thing we'll reference here and in some of our gear guides, is that waterproofing for this category of goods is often measured by IP rating, which is something you can check (e.g., for headlamps).
Defining waterproofing for fabrics
When we talk about waterproofing fabrics for outdoor gear, such as tents or dry bags, and clothing, such as rain or snow jackets, first let's align on the right vocabulary. Sometimes these terms are used haphazardly by different people, organizations, etc. (there's no certification body that regulates what words can be used!). So here's our common sense definition for how we'll use these 3 terms throughout the rest of this guide (and, in fact, all of our gear guides & protips!).
|Less "proof" & expensive||More "proof" & expensive|
|Any material, e.g., any clothing you have on, will serve as a barrier to water; therefore you can say it's water-resistant. At some point though, this resistance will fail. When rain hits your clothes, you don't feel wet immediately because the clothes probably absorb the water. At some point, the material can't absorb any more, and the water soaks through.||A material that's hydrophobic, so it chemically doesn't bond with water molecules and water can't absorb into it||
While, for logical clarity, we'd love it if only the first definition were relevant, the reality based on how the industry defines waterproofing is that the second must also be valid
If you have a keen mind, you might be wondering: if something is water-repellant and doesn't absorb water, doesn't that make it waterproof (by the first definition only, obviously) because if it doesn't absorb water, how can water molecules pass through? Two points:
- Hydrophobic & water-repellancy generally refer to surfaces of materials. For example, think about wood furniture that may have a painted layer on the surface that prevents water from getting through, but once this damaged, the wood underneath is quite porous and water can enter; so we'd can say that this wood furniture is water-repellant but not waterproof
- This difference is also important to maintain because different technologies are used to convey water-repellancy and waterproofing, and these technologies have different use cases and fail points
Now that we have clear definitions, let's dive into how these states are achieved!
|As a result of the material's natural absorption rate of water. The more readily the material absorbs water, the faster the water soaks through to you! For example, cotton absorbs water very readily (it's more hydrophilic), while fleece and wool absorb it less (they're more hydrophobic, in that order). One can also modify the absorption rate by changing up factors such as thickness or density (the higher either of these are, the longer it will take for water to soak through)||Historically a chemical coating (DWR, or Durable Water Repellant) that causes water to bead up on the surface. Innovation is ongoing to use less toxic chemicals. As it's just a coating, and the fabric itself isn't hydrophobic, this technology alone is not enough to allow a full claim of waterproofing, since the coating can become thin and wear out||
*Coatings are pretty much the only solution used for gear such as tents. While clothing generally uses a membrane, but may also use a coating. That said, breathability is more important for clothing than for gear, which can become a limiting factor, as silicone is not breathable, so any clothing that uses the superior waterproofing of silicone coating must have lots of ventilation zippers to allow adequate breathability. For more information on the importance of breathability, check the next section.
**Different inner layers may be used which affects functionality; read more in the our clothing guide, see the section on Outer layers.
A minor point on seams & taping
Waterproof fabrics, whenever sewn together to create the structure of clothing and tents, will be punctured by the needle and thread. While this may seem tiny enough to be inconsequential, it's actually not! As a result, any seams generally have to be sealed by a waterproof "tape" or liquid brush-on sealant. Alternatives to this include: some advanced sewing techniques themselves make it hard for water to travel in, and this may be utilized as well to minimize reliance on or to complement chemical treatments, where seams are welded together rather than taped.
The 'Water Within'
For clothing especially, it is entirely possible to get wet without a drop of rain penetrating through your outer layer! We'll demystify why, because this is often why people report getting wet, rather than because a waterproofing technology has truly been compromised.
Waterproofing, at least at quick glance, seems pretty easy. Like... plastic bags are waterproof, just put one over yourself when going outside, and get a huge sheet to cover your tent! Well... it's not so simple. Think about the pop-culture joke (is this real?) of wrapping yourselF in plastic and then sitting in a sauna or getting on an exercise machine to really sweat it out. Sounds like a miserable experience right? That's because plastic bags are waterproof--duh! And sweat is water so sweat also will not escape!
In fact, historically, people did just deal with trade-offs like this. Early waterproofing technologies that used wax to coat clothing resulted in the wearer feeling oppressively humid and hot at times!
The point is, within an enclosure such as clothing or tents, there's going to be internal sources of water! We've listed them below, obviously there are mitigation strategies (e.g., don't exert yourself, carry anything wet, etc.) but you'll never get rid of all the water from internal sources.
|Liquid state||Gaseous state|
|Sweat||Wet things||Breath||The very air|
|The more you exert yourself, the more sweat your body will generate||Anything wet, is obviously something with water||Whenever you exhale, you're breathing out some water vapor (this is what condenses into the 'breath' that you see on a cold day). The more you exert yourself & the heavier you breathe, the more water vapor comes out||There is always water vapor simply in the air (obviously less if you're in a desert, more if you're in a rainforest or next to bodies of water) that you'll "trap" around you with clothes or a tent|
In the table above, we called out the states of matter internal sources of water will be found in. This was kind of a hint! Basically, modern waterproofing technology works by relying on states of matter: keeping liquid water out while letting gaseous water vapor evaporate through. You can see this below in a diagram for how a waterproof-breathable membrane works. A few notes:
- While not shown, the coating waterproofing strategy would look very similar, except there'd be no liner, and the face fabric & coating would be more "glued" together
- Notice that the external side of the face fabric shows water beading up, this side is itself coated to be water-repellant, minimizing the amount of water that reaches through to the barrier; we'll talk about why in the next section: Where does the vapor go?
Since waterproofing relies on states of matter, this means that any internal sources of water that are liquid must be transformed into gas before they can be let out. This is why in our clothing guide in the section on Base Layers, you'll read about how the primary purpose of a base layer is to moisture-wick, take your body's liquid sweat and facilitate it's evaporation (it's conversion to gaseous water vapor), that can then escape the clothing's waterproofing mechanism. But there's not much that can be done about wet things, so... don't store wet things in your tent or wear wet layers!
Continuing the physics lesson, you may be wondering, how does gaseous water vapor like evaporated sweat "know" to... leave? What if it just hangs around inside the jacket or tent?
At a high level, vapor moves toward equilibrium, from where there's a high concentration, to spreading out to areas where there's a low concentration (so does liquid water, think about dividing a bowl in half and filling one side; once the barrier is removed, the water quickly fills up the other side until it's level across the entire bowl). Typically when you're working out, there's a lot more water vapor immediately around you generated by your sweat than in the environment, so it moves away from you. But this doesn't have to happen.
If you've ever been in humid areas, that's why it feels so clammy; water vapor doesn't move away from you (sweat may not even evaporate!)! So your ability to feel like waterproofing is working, especially if there's a lot of water vapor from internal sources such as if you're working out, is directly tied to the amount of water in the external environment! And this sometimes will lead directly to trade-offs you have to manage for yourself. For example, heavy rain outside means any vapor trapped inside may not move out into the environment very easily, and regardless of how breathable a rain jacket is, you may just feel clammy.
Beyond environmental trade-offs, this highlights a key concern with gear. If the face fabric of a jacket, for example, is very wet, then any sweat vapor may not pass out into th eenvironment! That's why any gear that needs to be waterproof and shelters something with an internal source of water must also be treated to be water-repellant. If the jacket's face fabric is water-repellant, then water doesn't absorb in or build on the surface, creating the necessary conditions for sweat vapor to pass through. This is why tents & outerwear utilize both waterproofing and water-repellant technologies, while something like a dry bag that is just a container for gear, generlaly just has waterproofing.
If water vapor is just... around you and not leaving into the environment, that may be tolerable. But if it's actively condensing into water, then that can be very uncomfortable!
Think about water droplets on a drink. The droplets are water vapor in the air condensing due to the coldness of the glass. Or think about how you wake up in a tent, and you may see the tent wall directly next to where you've been breathing all night wet with droplets: that's your warmth breath condensing on the cold tent fabric! And remember, tents are waterproof so liquid water can't pass, only vapor can. Any condensation, or any liquid water, on the inside just stays there.
These examples serve to illustrate that condensation happens whenever there's a temperature difference. Water in liquid form has a higher thermal energy, and whenever it meets something cool enough, it will tend to condense.
Boiling down (pun intended) all the physics, dealing with the water within comes down to 3 strategies, for which we'll provide some tips or tricks.
|Minimize amount of water within||Optimize passage of water within as vapor out into environment||Reduce likely that water vapor will re-condense|
*But not under a widow-maker that looks like it may break or fall!
General tips include:
- Maximize ventilation (unzip clothing, open rainfly vents or tent windows) - encourages airflow & equilibrates temperatures
- Take on/off layers so you don't excessively build up sweat vapor (don't be lazy and just keep everything on!)
- Move locations! To somewhere drier or warmer, if you can!
Maintaining water-repellancy & waterproofing
Quick note, water-resistance, as we define it, is just based on the absorption-ability of a material. If a material is fully saturated and passing water straight through, to build it's resistance back up, you just have to dry it again
For clothing especially, to keep vapor passing out, you need to ensure the waterproof layer is not clogged by body oils or dirt, by washing. On the other hand, washing will wear away at the water-repellancy treatment, and while you can (and should) wash with special detergents, include those that rebuild water-repellancy, the trade-off can feel like 2 steps forward, 1 step back. That's why as a rule-of-thumb we only recommend washing waterproof outer garments once at the end of the season, and always wearing layers underneath! If you need assistance we do provide some cleaning & repair services (while we're working on your gear you can get a discount on renting outdoor gear). And if this entire protip has made you think... what a hassle, well that's why we rent waterproof clothing and all sorts of outdoor gear!
|Visual cue||Why you're getting wet||How to resolve|
Water no longer beads up on the exterior of fabric & absorbs into it
You see a dark spot where the fabric has "wet out" (is fully saturated)
If the gear is just water-repellant, you're getting wet because water is soaking through to you.
If the gear is also waterproofed with a coating or membrane (and other visual cues are not present), you're likely getting wet because the high concentration of water on the exterior of the fabric isn't facilitating the escape of internal water vapor
|Rebuild water-repellancy with spray-on treatments or detergents|
You notice water leaking in, particularly around seams
You physically see strips of tape peeling away along the seams
|Water is entering through the seams, which have needle puncture holes||
Use a liquid seam sealant along the seam, or re-tape seams
Re-taping is often harder, since it requires you to know the exact fabric you're repairing (different fabrics have different application requirements for different seam tapes)
There's a rip or tear, or other form of visible damage on the exterior
||The waterproof coating or membrane has been cut||If a very small spot, you may be able to apply a patch of waterproof Tenacious Tape. For major issues, the best way is to sew on a new patch of waterproof fabric, then seam seal where it has been sewn|
You notice flaking*** on the interior of the fabric (may be accompanied by a nasty smell, particularly for old gear)
||The waterproofing coating has begun to flake off. Water will enter once the fabric "wets out" when the water-repellancy also fails||You need to remove all the flaking (a rare instance when the abrasiveness of a washing machine is fine) and then reply the coating|
***It's worth mentioning that this flaking is distinct from situations where you have a 2.5 construction jacket (for information about this type of jacket and how to recognize it, check our clothing guide) and what's flaking is the interior liner that protects the waterproof-breathable membrane, see image below. Generally a visual cue would be a printed pattern of some kind inside the jacket is flaking. This is just an issue with the liner and likely will not affect waterproofing (if the membrane isn't damaged). However, it's not fixable. You may want to clean slightly more often to clear membrane pores
Cleaning stains from water-repellant fabrics
While this is not entirely relevant to keeping fabrics waterproof, it is important to mention particularly for clothes, where style & fashion may be just as important to the wearer as functionality. With this regard, we have not-so-great news. Being water-repellant fundamentally means that the fabric resists the intrusion of water. To clean stains, water & soap have to penetrate into the fabric. You can see why this is a bit of an impasse, and we've found it to be a fundamental trade-off. Anything that helps remove stains, e.g., scrubbing or using alcohol or other stain removers, will not be good for the water-repellancy treatment. And while you can re-build this treatment (the primary purpose of technical detergents, which sadly also don't help that much with staining), it's best to minimize harm in the first place. So the conclusion is: your technical gear is just going to get stained!
Luckily, most people understand that going outdoors isn't the best "low-stain" activity. We will make a more conscious effort to retire rental clothing, understanding that people are more sensitive to the appearance of worn items, than other rental camping gear for reasons of staining. For more information, review our rental gear condition