Backpacker Fact-Checker, #3: Inflating a pad with your breath 

This really is the most scientific approach to backpacking I've ever seen. Clearly a five star channel.

This is SO the video that we need today, especially with seemingly everyone starting to carry yet another electronic gadget that’s just not needed.

Nothing is more exciting than receiving a Gear Skeptic video notification.

As always, Thank you. Too much of what we believe is marketing. Someone who looks for facts and evidence to support it is a rare and precious commodity.

Your videos are OUTSTANDING! Id love to see a comparison of warming/cooling/wicking base layers, mesh, merino, synthetic etc. As only you can do, of course...

Thank you for this. I am one of those people who perpetuated the dogma about not blowing into an air pad. Which is ironic because I often talk about not blindly accepting these type of unsubstantiated wisdoms. A good prompt to examine what I am saying myself. Having said that, the small pumps still make the inflation job easier😉. Thanks for sharing

Gotta thank you for this one. I was very worried about mold growth in an insulated pad, and it's been keeping from getting one. I saw that same patchy pad photo and thought I would need a pumpsack or portable pump. Thank you for clearing up misunderstandings on the topic so thoroughly and objectively.

This is brilliant, thank you. My number one reason for using either an inflation bag OR pump has more to do with the fact I feel really, really, dizzy after inflating my mattress by mouth! Thanks again

As a scientist who likes backpacking, I salute your approach. You have a new follower! There is a lot of marketing & hearsay in the community, so we desperately need some mythbusting.

Lets go!!! Excited to watch. Would love to see a video on Natural v Synthetic clothing and what is the best for durable and sustainable options.

HELL YEAH! THANK YOU FOR THE NEW POST!!🎉

Great video. I wish more of the internet was this well considered, researched and reasoned. The world would be a better place!

delightful breakdown and discussion. Thanks Gear Skeptic for being such a great voice in the outdoor gear comunity

The main idea I’ve heard regarding inflating a sleeping pad with your breath in very cold sub-freezing temperatures is that the warm breath will contract as it cools and further inflation will be required to retain full inflation and therefore full R-value. I’ve not personally heard debate about internal condensation compromising the R-value, only debate about condensation and mould. Anecdotally, I live in a cold, humid place and rainy trips of several days can introduce visible internal condensation even using a pump sack with the humid air. My pad gets a funky smell on trips like this that I notice when I deflate it, but airing the pad out at the end and cycling air through several times dries it out fine and gets rid of the smell.

Wow!!! a pair of talking hands. One of the best videos I've seen on the subject, and it aligns with what I have thought for many years. Cheers from the mountains of NZ ☺☺

Thank you for continually scratching that itch! We all benefit greatly.

Somebody is going to ask me why it took half an hour to brush my teeth.

It always amazes me when people say “you must use this new device”… and it never seems to occur to them that human race got right here without that device.

Time to return my flextail pump and save 45 grams and give everyone their quiet back .. ..😅

Thank you for another great video. Your hard work and dedication are greatly appreciated. Please keep making videos. ❤

I love your videos man, you're that kind of people we need more! All that effort to get the result as neutral as possible, based on real facts (as good as possible), that's the way! Thank you so much for all your videos!

Loving the content! Keep it coming!

Thanks again for your work. I love facts❤️

That was very thorough and clear. Impressive!

This is my new favourite channel

I love the detailed, logical approach. I also kind of enjoy that you talk with your hands. It's a unique form of expression!

Great video and as usual full of sound logic. Really love everything you have put out and your nutrition and hydration series are fantastic as well as the new windscreen videos. They have helped me make more informed decisions, and to some degree relief that I haven't been far off the mark all these years. For me, I do use a pump, in fact, the very one that you show that I got at the beginning of the year. At least in my case, it has nothing to do with moisture or humidity, it's a time and breath saver. Put up the tent, attach the pump, and do something else with my time. Also no feel lightheaded as I blow it up. It's an unnecessary but small luxury item that to me is worth it.

Your academic, ahem, scientific approach is so desperately needed nowadays to help sort through the noise. Thanks for all you do.

Well done, Well thought through, and Well said.

Thank you for all the hard work! Helpful and fun video!

Once again, thank you for the excellent scientific presentation. This is some of the best content on YT.

Excellent video and wonderfully realistic clinical approach. I love this series and find it very helpful for people to have piece of mind. You’ve got a new sub and cheers! 🤙🏽

Thanks for the investigation! I always had my doubts and by doing some field testing I never experienced any negative results of blowing my pads up with my mouth. Bud it's nice to get some more information and deeper testing on this topic. Stay warm and cozy!

Another great video! I can't wait to see what you debunk next.

Your content is like engineerguy on youtube. Substance in every sentence and you got the facts to back them up. You even sound like him. Great videos!

So happy to see this. My S2S UL pad has taken 9 years to start to show mould growth. I think that’s a pretty good life span for a sleeping pad (and I’m still using it - mould and all)

I LOVE your videos. Thank you for these, and the sense of humor :) I find them very helpful.

Thank you for making this video and doing all of your research. I have never used a pump and always thought this mold issue was nonsense and it’s nice to know the facts. Take care

Another fantastic video. Thank you very much.

Great explanation!

Another great video! Well researched and presented! I am friends with and backpack with Devin, who is Backcountry Exposure. I can vouch for his video and his credibility. I think you have cleared up this mold myth! Also the R-Value issue with humidity from your breath. Thank you for another great video! The reason I got the zero pump is I’m tired after a long hike and was the luxury of having a pump inflate it for me. But I did not buy it for a warmer pad experience or to cut down on mold growth.

Great work, thanks

Nice video. Did the AT last year and at first used breath then pump sack and personally, both methods suck. Especially after a long day on the trail. Purchased a small FlexTail and it made a world of difference to me. For me, having the means to connect the pump and start inflation while I do something else was a small game changer.

Planning for a 3 nights winter ski travel in Canadian snow using a 33 YO Therm-a-rest. This video is soooo useful! Thanks!

Great video, great channel.

Thank you! Again, as always! So good and tons of fun! My two thermarests, tiny pump, and older lungs thank you. Now I can officially proclaim the tiny pump ‘just’ a luxury item.

Learned to use my nylofume pack liner as a pump sack which I’m already carrying and only top off with a couple breaths. Avoids the myths 😂, and does have the real benefit of at least filling with ambient temp air rather than warm breath. That helps with air pressure inside the pad as it normalizes in my experience. Thanks for your work!

Great analysis, definitely a new subscriber! Have to check out your other Fact Checker videos.

at last somebody who asks himself questions and questions all those clichés served to us by just about every influencer on youtube. great job. ciao from Venice (Italy)

Thank you for all the work.

I am a retired engineer and I really appreciate the data driven approach to backpacking provide here. It was interesting to see a reference to a data source I often used in my career. Btw an obvious way to avoid the pad issues is to use a hammock instead of a pad and tent system. But that’s just me. Again, great video. Hope there will be more like this.

Nice! I have thought about this from time to time, but it never bothered me enough to carry the weight of an inflator. Now it won't even bug me any more.

I've recently discovered your channel and find the data driven and unbiased analysis fascinating and truly helpful. I'd like to support your work for the knowledge you've provided me and was hoping you had a merchandise page or a Patreon available but there doesn't seem to be anything. Looking forward to your next upload. best regards from the UK!

Greetings 👋👋 OK…. I hardly know where to start. I’m not sure now if this enlightening video was the first of yours that I watched, cause I’ve watched so many now. But in any case thanks. I’m not really a backpacker but a 75 year old who motorcycle toured and tented back in the 80s, got away from it for 25 years, and now hammock camping out of an inflatable kayak. So limited space. Your videos on stoves, filtration, etc so helpful.👍 I’m gonna try say this respectfully and tactfully 😊…. Your videos give me “more” information than I need but you present it SO WELL that I take it all in….And enjoy it. And I think of the time you invest in these and I truly wish there was a way to get more eyes on them so more folks could benefit. Maybe you have to click bait the title with “Naked backpacking with NO bug spray “ or something as silly. In any case..thanks so much for doing these.

Excellent, I have watched a few of your video's in the past...new sub now. These are great examples and I really appreciate the effort done to prove / disprove the marketing research or trail legends.

I love your videos, but as an chemical engineer, I would refer you to heat transfer text books. There are 3 forms of heat transfer, conductive, radiant, and convection. I think you were correct at focusing on thermal conductivity of humid air. Convection likely dominates the others. As the air circulates in the air pockets it will transfer heat from the warm side to the cold side. I agree that neither the humidity nor condensation will affect the heat transfer.

Great video. I never bought into the mold theory as the pictures shown to be mold were mostly delaminated Xlites.

Thanks for filling the science-less consumer gear void as always. An itch that I never knew I needed scratched 😉

Great video. I use one of those small pumps anyway. Great for starting the fire but now I won’t worry about inflating it with my mouth. Thanks

Bel exemple de démarche scientifique! En l'absence de tests exhaustifs, raisonner à partir de connaissances de base de la physique. Bravo!

Great stuff 👍

Another great video. I send every hiker I meet your way. I do have a single anecdotal case of moisture build up in a pad. A fellow hiking buddy on the AT had considerable moisture build up in his pad, actual pooling could be seen in it by the end of trail. It is however the only case I have ever seen. I also saw a single case of mold, but watching this video it was likely just the inside coating wearing off. I still use a pump sack because blowing up a pad is exhausting as the end of a long day, especially at high altitude, I get very dizzy.

Super interesting, thank you!

Interesting discussion/video. I've used self-inflating pads on two thruhikes and lots of other trips including winter. Always wondered about the effect of inflating, but never had any problems I could relate to moisture buildup. I've had one Thermarest delaminate partly creating a big bump in one end. Had it replaced for free though so couldn't cut it open to examine the inside. I've never used a pump, but always let a self-inflating pad try to inflate itself then take shallows breaths to inflate it fully. For non-self-inflating pads I just blow and don't worry about it as it's much less "stuff" inside that could absorb the water.

You rock. Thanks for sharing this

Another great video as always 👍 (and for anyone else wondering as I did initially about why then the heat index goes up as the relative humidity climbs, the answer is because of less evaporation of sweat rather than high heat transfer from the humid air)

Great video as always. Just a food for thought. The only scenario where humidity could affect heat loss, would be at really low temperatures. How? Latent heat. If humidity causes condensation on the inside surface and you would touch the same surface with your body from outside, warmth of your body would make the moisture EVAPORATE which will drain some heat from you. That vapour would condensate again on the surface you are not touching and as everybody moves in the sleeping bag on a mattress, this process would repeat itself. However, the amount of water is not big so this heat loss will be probably still negligible.

so appreciated!

Very cool, informative and entertaining . . . 10 breaths for me but I use a medium. I deflate my X-Lite mattress while I'm still lying on it and the air in the mattress is warm so it carries the humidity out when I deflate it as your experiment suggests. Even the ground is warm when I feel it. I have never slept directly on snow so I doubt there's any condensation. Every once in a while I would blow it up and set it in the sun for a while and then deflate it but it seems that's not really necessary and the mattress never did get any funky smell to the expelled air suggesting nothing is growing in there.

👍👍👍 .. another good one 😊. 'Possibly' in the distance, the sound of the gnashing of teeth from manufacturers of said 'pumps' and such. However, only a Sceptic would be able to prove / disprove that mantra 😏. Thanks for the research and the share ..

Thanks for all these videos, and for demonstrating a rational way to question the accepted wisdom that’s purveyed with such certainty by so many.

Great work, thank you

Mission Accomplished! Great video as always, though I am surprised that there is little to no research in this area. The mold issue was something that I was always a bit worried about, but I figured that as long as I did not suck the air from it, it does not really matter.

Love your videos! My one luxury item is the XLite NXT pump sack that I keep a few things in. Tried using the nyloflume liner on the Xlite but it leaks too much so I'll need to practice some more.

My pad appeared to have mold inside. I cut it open. No mold at all! Deterioration of reflective film. since then i have suffered from hearing the claims of mold but knowing the truth. This video has lifted that burden. I thank you, my autism thanks you.

These are great! The algorithm finally decided I need to know about your channel and I am catching up. Another camping sleeping associated heat loss that has differing opinions is whether to get up and pee (and jettisoning 800 ml of, presumably, already warmed water) or hold it and its heat in. My personal practice is to keep my reliably sealed pee bottle inside my bag as a hot water bottle (I also hike solo so I am all about risk taking :)

Great video, as always. And very timely given the volume of pump zero ads I see. I’ve been use the pump sack that comes with the Xtherm, but if it’s not windy I have to blow into the sack a bit anyway. Now I know I can dump the sack and just blow straight into the pad with no worries.

Thank you! Interesting discussion, as you say it’s complicated. For moist air, I suspect that convection will be the dominant heat transfer mechanism rather than conductivity. The risk is that a matt filled with moist air will act as a heat pipe, this is an efficient method of transferring heat which is used within some mobile phones and even satellites. A heat pipe increases the rate of heat transfer through a vapour that condenses on one colder surface and evaporates off a warmer surface within a cycle. A pad containing moist air could work like this, the warm top surface will drive warm water vapour to the colder bottom surface where it condenses, transferring more heat due to the latent heat within the fluid. Baffles etc will reduce and its difficult to model. Its difficult to analyse, even with computational fluid dynamics and heat transfer software. Best way would be to do a comparative test, like you have attempted, perhaps with a wider heating pad to reduce the edge effects and directly measuring the temperature under the pad during the test rather than with a heat gun. An alternative would be to measure the temperature on the top surface directly under the heat pad, perhaps beneath a cloth to simulate some clothes, both heat pads and mats would have to be identical, ideally two pads (one dry air, the other breath) tested together at the same time. It would be important to ensure that the two set ups are completely identical and this could be checked before the test by first running the pads and temperature measurement in identical conditions and checking that the temperature beneath the two pads is identical-ideally something realistic like 36 degrees, with a cooler floor temp eg like 5 degrees. Any difference between a breath inflated and a dry air inflated pad would be due to the moisture, if no difference then impact is not significant. This would be very interesting and measuring on the top surface would be more realistic. I am in the blow it up with my breath camp, I suspect that if the increased heat loss is not negligible, choosing a higher R value pad would still be lighter than carrying an electric pump. Wonder if thermarest has tested. Since they now sell an electric pump, maybe they have an interest. I remember that previously their product guidance indicated that it was fine to blow up by mouth. Great channel!

GearSkeptic, you're one cool dude. Thanks for sharing your research with us fellow hikers. You're videos are dense with facts and fact checking among other things. We've seen what you UL foods you bring out on a long hike but havent seen your personal hiking gear list. Could you create a video on that with your humor, lol? I'm sure I'm not the only one interested in seeing this.

Another home run !!! In recent times I feel like I am bombarded from every direction with claims that irratate my common sense intuition......I listen but usually go with my gut....and this is in everything not just gear.....I know I am asking a lot but would GearSkeptic consider expanding and take on the world of ridiculous claims ?......and yes I blow my pad up with my breath. I have used this one for two years and have started smelling the air exhasting from the pad and never get a whiff of mold.....once again vindicated by GearSkeptic....!!!!!!! Thanks a million....!!!!

Best Hiking Channel Ever.

Thank you for your unrelenting backpacking scientific nerdiness! I’m ditching my nemo vortex inflation bag this year!

You're a hero

Thank you! I’d always wondered about this, and now can stop feeling bad about blowing up my synthetic exped!

Good video 😁

What an awesome, thorough analysis, thank you! This is real quality content. Personally I carry and use the pump sack with my nemo tensor. It's 2oz and packs down to nothing so I'm always surprised that carrying pump sacks can be so controversial. Yes, I'll admit one of the reasons I've used it is the mold growth thing, but a big reason is also that it's just much easier. At the end of a long day of hiking, huffing and puffing into the valve in a contorted position in my tent is absolute misery for my lungs and back. Even if we say the whole humidity thing is debunked I'm 100% still going to be bringing my pump sack.

Quality content

This video saves me the money and the grams of carrying a pump or pumpsack! Great content! Thank you!

And here i am shouting at my screen: "But how about in freezing temperatures?!". The myth that i've heard is that moisture freezes during night and therefore ice accumulates in the pad. If i interpret this correclty this shouldn't be huge problem considering amount of water getting in to the pad. Although i am pretty sure not as much moisture exits during deflation, since bigger part of it should be condensed at cold side of the pad.

Man I'd love to see you tackle "don't hide in your sleeping bag you'll add condensation which will make you cold", I've heard that recited over and over

On weather forecasts, some show “temperature”, and “Feels Like”. You might find a chart there that gets you a bit closer to what you seek? Courtesy of Half Vast Flying

17:30 that's one noisy pad. Thanks for great video again.

YES to the t-shirts!

Lol, loved the new message

Thank you so much. Now I can sleep better😄😴

I'm really glad Thing cloned himself, got an interpreter, and became scientifically educated. He really has grown.

the logic I've always heard is that our breath starts out warmer than ambient air, when it cools down the pressure drops and makes the pad feel less inflated. so ambient air can in theory keep a pad more firmly inflated. glad to know mold and insulation are a non-issue without a pump

Love the thoughtful video, thanks. I think the only issue around using "breath" to inflate a sleeping pad is the fact your breath is likely to be warmer than the outside air. This will cause the "breath" -air to cool and condense. Gasses (e.g., breath-air) take up less space as they cool (air condensed as it cools) so we will have slightly reduced R-value as the cooler matt is thinner than it was when you blew it up. This matches all my experience as well. I blow it up when I unpack and set up, only to find it needs a few more breaths before I go to bed.

I still appreciate my pump sack, even if it's just to avoid getting winded when trying to set up camp. 😁 Thanks for yet another great video!

For me, it's obvious that you have laid to rest a couple of myths that have permeated the BP community. I don't use inflatables that much in my camping, but what little I do use, I prefer to inflate with dry air. I have my reasons. I will not purchase an electrical gadget to do the inflating. I prefer a pump sack of some sort. They are multi purpose and add no appreciable weight to my kit. Thanks for an objective view on yet another topic. Very well done........Be well.