Ideas for adding low bulk, low weight insulation to tent

It’s 55 for a little under a liter. It doesn’t have to be 5mm thick. My original plan is to do two coatings on the Silpoly fabric, which should average somewhere between 2.25 to 3mm thick–most of that Aerogel particles (since a particle is about 1mm thick). I earlier said that if that wasn’t enough, then I’d might do a layer or two on the cuben itself.

That’s just the aregoel.  Then there will be added insulation from the two air spaces between 3 impermeable fabrics + IR reflective material. Since I’ll be also be using a couple candles as extra heat besides my body, the above combo may be more than enough. That’s where experimentation will come in.

Also, the entire tent will not be covered in this.  A good chunk of the door area, and the peak vent will be covered in Apex lined in very breathable fabrics. That’s to increase breathability of the tent, without completely reducing insulation.

I might just save up and order the kilogram of Aerogel from China for a total of 380.  A kilogram of Aerogel particles will be a huge volume of material (I’m waiting to hear back just how much). I have a number of ideas for other projects involving aerogel, including a super insulated, low weight thermos, low weight super insulated mittens, etc.

Will Buckyballs work in a silicon matrix and are they an option? Are they even an affordable option yet?

You do know that insulated tents were tried back in the 50’s? Anyway, I see Aerogel as too brittle for tents. The cost, in weight, of the silicone binder would be a LOT more than foam panels to achieve the same insulating value. This ignores the packing problems breaking the “crease” areas which would not, by itself, kill the attempt. Try it, I would like to see the results.

To James M:   For a tent?  The only compression it experiences is during packing and for the inner material some abrasion during packing and unpacking. Obviously I would be more gentle with it, and probably it would be the last thing to go in my pack–right on the top and if not, covered with a down jacket or the like.  Silicone is a good matrix for it because of it’s rubber like nature. I’ll probably have to re-coat it every once in a while with a new silicone layer to keep it maximally protected.

380 total for a kilogram initially sounds like a lot, but when you think about the fact that this material is almost 99% air… then you you realize that the volume for 2.2 lbs must be quite large indeed.  Even with some extra projects, I don’t need anywhere near 2.2 lbs though. Maybe I could find someone to go half with me on it.

I disagree about the same insulation value as foam–maybe at a similar weight comparison factoring in the silicone, but certainly not at the same volume. 2mm of Aerogel is equivalent to 4 to 7mm of foam at less weight (depends which foam, they’re not all equal). The silicone matrix definitely adds some weight, but probably not as much as some may think.  The average waterproof coating of silicone on a fabric is typically around .25 to .35 oz/yd2. The amount I’ll use will probably be closer to about 1 oz/yd2 extra.  The aerogel particles themselves will add barely noticeable weight. Maybe an ounce or two for the entire project, if that.

Since the mix of aerogel+thicker silicone will be highly fire resistant, that’s also a plus compared to foam. I will be using candles and/or small wood cooker in there.  Nor am I dead set on using silicone adhesive–I probably could use cheaper silicone caulk with good results.

Also, this is not just for backpacking, but also will be part of my bug out bag. I consider it investment in an uncertain future, besides just for play and experimentation.

But yeah, it would be ideal if someone was interested in going half and half on this. 1.1 lbs for 190.

I would’t compare this to 1950’s at all.  There was nothing like Aerogel on the market then (nor many other materials we use for tents today). Aerogel per weight is many times more thermally efficient/resistant than even good quality Goose down, though obviously Goose down’s compressibility and fairly durable nature is a big plus over the former.  I wouldn’t make a sleeping bag out of Aerogel, at least not as the predominant competent, but then again, we’re not talking about sleeping bags.

Aerogel was invented in 1931.

Monsanto started to sell it in the early 40’s and so for 30 years after that.

It wasn’t very commercially viable then. It’s been in the last few decades that it started to be mass produced in large quantities at commercially viable costs, both for the manufacturer and for the “regular” or larger market.  NASA for example, is NOT the regular market.

For example, from a wiki page, “However, Monsanto dumped Kistler’s aerogel around 1970 because of high manufacturing cost* and competition.”  Excerpted from: http://creationwiki.org/Aerogel   *My use of bold and italics. (And Monsanto was a big, profitable, deep pockets corporation even back then).

There are many people today who know very little about it. A couple of people on this very thread had some big misconceptions about it.

I was speaking of commonly available, affordable materials (such as would be used on a tent back then).  Not to mention that various improvements have been made on the material in many ways, even speaking of basic silica based aerogel.  The first silica based aerogel made was hydrophillic and broke down in exposure to water.  Now hydrophobic treatment or process is very common.

Hey, Kobe Al alloy is technically on the market now, but when will you or I ever see, let alone be able to afford it?  I’m sure the military industrial complex is eating it up though.

And your point was what?  Just being your usual self?

Based on the info on the product sheet, 1 kg is 7.4L which will coat your tent with 2mm, providing an R value of 1.6 at 4osy (not including the silicone).

In comparison, 2.5osy Apex has an R value of 2 and readily compresses to 2mm.  The aerogel form China also costs about 20 times as much.  You can pick a different thickness to arrive at a different cost, weight and R value, but the intrinsic material properties are heavier, bulkier and more expensive than Apex for equivalent insulation.  There’s no win here on those metrics.

This is just arithmetic.  I encourage you to pick up a calculator and figure out what you’re actually working with.

Ok, here’s an off-the-wall solution. What about a tent with baffles that could be filled with snow? Sort of like a pole-supported igloo. You could call it a Tentgloo! With silnylon it should end up lighter than the 2.5oz apex.

I suspect there are probably a lot of reasons why this would be a bad idea (such as the snow melting and then freezing to the tent, or silnylon not being strong enough). But it’s worth further thought.

I wouldn’t do it for myself but I applaud the urge to experiment Rene.

Also don’t discount triple walls so quickly. Even tho it isn’t dead air if the space is about 50mm it works reasonably well. I just had a thought about baffling that space with the UL mesh in the same way that sleeping bags use “V” or “W” baffles to contain the down

I understand that part of your thinking is to make the insulating layers as thin as possible to maximise interior space. I tackle that issue by taking a much bigger shelter and more weight \Totally different ways of looking at the matter

Hi Rene, do you have a link to the product sheet where it says 1kg equals 7.4L for the particles, thanks?  When you’re saying 4 oz/yd2, are you factoring in all the other materials besides the Aerogel particles?   Because if you’re just talking the weight of the 2 or so mm of aerogel itself, it seems WAY over estimated. Keep in mind this material is about 99% air.  For me, 4 oz/yd2 includes the weight of Membrane SilpolyPU4000 material, little foam strips, silicone coating/matrix, aerogel, mylar space blanket, and nylon tulle all together.

I originally thought of Apex, but I’m worried that frost could get in it either through condensation or increased permeability at low temps.  If I use 2.5 oz/yd2 Apex, then I’m looking at a total weight of about 5.5 oz/yd2 of connecting material, because I would still want the IR reflecting aspect.

But there are other benefits to the Aerogel idea besides lower weight and similar bulk. If frost does happen to get in that layer, it would be A LOT easier to get it out in the field, then with Apex insulation. I will be using fire/flame sources in same, and the combination of Aerogel and thicker silicone coating is pretty fire retardant compared to Apex and non Aerogel+thicker silicone coated materials.

Granted, if the nylon tulle and space blanket caught, they’d readily go up in flames, but the outer layer of coated Membrane would have a much harder time, and would protect the cuben behind it, giving me some time to try to put the rest out.  Otherwise, with just Apex and no coating, it ALL would go up pretty dang fast.

I don’t mind losing a layer of tulle and spaceblanket, but I would be pretty bummed about losing the whole thing, especially the cuben.

Hi Nick, could possibly work, particularly in certain areas of the world or this country. The areas that get a lot of light, powdery snow consistently might work. You’d probably still want at least an IR reflecting liner to help keep the snow cool enough where it directly touches the tent. The new “Mountain” silnylon at RSBTR might be a good choice for such a material?  But silpoly might perform a little better if it got wet.

We don’t get a lot of snow here, and often when we do, it’s the heavy, wet stuff.  It’s also fairly common for it to dip above and below freezing, off and on, a lot. Probably wouldn’t work very well here because of those reasons.

Edward, I would be strongly interested in that idea if I could replicate something similar to the Neo-air type baffling, but without cutting mine open and trying to figure it out that way, I don’t have much of a clue.

I do think your general idea of 3 UL fabrics and air space idea would apply better to a larger tent.

If I lived in CO or someplace similar, I’d probably try Nick’s idea in combo with an IR reflective liner. Lightest and least bulk of them all so far.

Justin I’m fixed camping again next ski season But I’ll be in another old fashioned canvas tent with enough room for bulk insulation on the roof and my wall tent is 8’6″ * 7′ and 6’6″ [ 2’6″ walls]  tall so solo I have that room.

If I was doing this UL and no wood stove it would be a different bottle of anchovies

It’s your link.  It lists 120 – 150 kg/m3.  Split the difference and 135 kg/m3 equates to 7.4L/kg.  4osy @ 2mm isn’t an estimate, it follows directly from the published density.

The problem with, “For me, 4 oz/yd2 includes…” is that you don’t have anything to back up the claimed weight.

Take a look at this: https://cellularwindowshades.com/content/33-rvalue

Hmm.  I didn’t pay careful enough attention to the spec sheet.  It lists ‘particle density’ which is consistent across the various particle sizes among their different products.  That means the density isn’t for a volume of the product – lots of particles – it’s for a solid mass of the substance.

That means a given volume of particles will have a lower density.  If they were all the same size (they’re not, there’s a range of 10x dia.) and spherical (they’re not – zoom on close up photo) they’d occupy around 64% of the volume, for a 36% effective reduction in aggregate density over particle density.  With mixed sphere sizes they’ll occupy more as the small bits occupy the gaps between the big bits.

Reduce the effective density by 25%?  3osy for aerogel (again, w/o silicone) is a lot closer to 2.5osy Apex, but still 20% heavier.

If we fill that 25% void w/ silicone sealant, we add 13.66osy for a 1mm thick coating, based on a silicone density of 1.29 g/cm3 listed here: http://www.matweb.com/search/datasheetText.aspx?bassnum=O5200

That puts all the aerogel grains in direct contact with each other – this is not conducive to flexibility, or the sharp creases that form when stuffing a tent.  For that you need to separate the particles with even more silicone.  If this sounds surprisingly heavy, that’s because this is a much, much thicker coating of silicone than normally applied.  RSBTR shows a common weight gain of .14osy – based on the densities of silicone and polyurethane, that says the coating is .003mm.  Maybe somebody w/ more familiarity in this area can chime in here.

Now we’re looking at 17osy for a 1mm, 0.8R coating?  Oh, not quite – silicone has a thermal conductivity 70x higher than the aerogel. The particles will effectively reduce that somewhat, but not by anything close to a factor of 70.

It is not looking like a silicone-aerogel coating is suitable for applications where mechanical flexibility and low weight are critical.

Even a coating of 10:1 mineral spirits:caulk adds a <.01″ layer and weighs about .1-.2oz/yd. I do this all the time on my tarps. Adding the Aerogel wouldn’t add much weight, but only improve R values slightly. The thicker stuff, like you are talking, would be more like a thick paste. It would be nearly impossible to spread without a steel trowel. Anyway, as I say, I am interested in the experiment. I would suggest a small piece and purchasing a small amount of Aerogel. Then adding some silicone caulk and thinning it to a thick paste. A yard of silnylon would be enough to tell you if it is feasible. I believe you need a different binder, though. Even at a .5mm thickness that would add about the same as 25-50 of my normal coatings. 25x.1=2.5oz/yd2…just for the binder.I believe you will find that the Aerogell will make the coating about 1-2mm thick.

Hi, I hate to throw cold water on the experiment, but I tried something different (but with some important similarities) earlier this year that I thought you’d be interested in. I was trying to build a backpacking oven. Very much like the outback oven – an insulated multi-purpose cover that would go over your pot with an alcohol stove as the heat source. I used an aerogel blanket (pyrogel) but also considered the very same particle and silicone approach.

I thought the additional weight savings would pay for itself in terms of fuel savings and ability to make more traditionally baked recipes.  I thought there seemed to be so much heat lost (even in a caldera cone setup) that if I could capture that and direct it to the water/meal it would be a very easy win. I was surprised that this wasn’t as dramatic a difference as I thought in the real world. This is not to mention the additional struggle of running an alcohol stove in such an enviroment (which is described well elsewhere on these forums by Jon of FlatCatStoves) – but just the nature of less than perfect real world materials/products and thermal dynamics.

In the (granted somewhat little) testing I did, I would be suspicious of the use of silicone. I think it conducts heat quite well, or at least did in that environment.

I tried exploring the idea of silicone bonded particles instead of the pyrogel blanket by getting a bag of perlite and seeing how they worked as an insulator glued on with thinned down silicone. Obviously, perlite is much bigger particles and would require more loft/silicone than what you’re talking about – but it was very heavy. The amount of silicone needed was a lot. If I starved the silicone it would just crumble and not hold well.

I guess my two cents are that aerogels are neat, but insulation in the real world is hard and I have to agree with a lot of what is said by others above.

Thanks guys for all the feedback.

Any suggestions for a different and binder/matrix for the particles and possibly doing it on the PU coated side instead? I do agree that silicone is a bit on the heavy side in thicker amounts.

Never mind about PU, realized that even very thin layer would make the fabric too stiff.

If the particles were smaller and more uniform, a silicone coat process probably could be refined to use less silicone. It would be easy enough to filter out the larger particles of aerogel, but refining the most efficient thicknesses (both particle and silicone) would probably take a fair amount of experimentation, so a truly efficient silicone coating process is probably out of my capability.

Hi Jonathan,

While there are some similarities, there are also some important differences. For one example, conductivity of different gases and solids can change with major temperature changes.  Also there is a lot more potential air convection involved with stoves and cooking, then in a more passive or slow heating system.

Kepp in mind, I wouldn’t be relying solely on the aerogel and silicone for thermal efficiency, but also on two air gaps between 3 waterproof layers and an IR reflector.  This will be combined with body heat and a couple of candles in a fairly small tent.

The question of will all this together work to insulate in such a circumstance is not really in question (in my mind). The main question is, what is the most ideal system for cutting weight and bulk, while being as thermally efficient as possible for the entire tent?  Another is the question of long term durability?   I’m open minded to the possibility that it might not be ideal in either category, but without actual experimentation and experience, it can be hard to fully and truly know something.

The Aerogel from China at first seem pretty expensive, but by volume, it’s not horribly priced.

I’m going to put some thought in creating a NeoAir like baffle system too. It might not be the most weight efficient, but it would be the most bulk and cost efficient and fairly thermally efficient.  I suppose I could take the idea of thin, small strips of foam (bonded on at the base) and apply it to a multi-level layer of space blankets, and sandwich these between two layers of the Membrane SilpolyPU4000.

Well, I finally heard back from an American based Aerogel company. The tech person who replied back said that any solvent going into Aerogel particles would damage them.

This could be circumvented by using an innately thinner, more flowing silicone from the get go, like permatex or silnet, but that would ratchet up the cost significantly and weight somewhat.

Conclusion: This project is likely too impractical to engage in, especially for someone without deeper pockets.

I will be focusing on creating a multi-layered, baffled, Neo-Air like insulation system for heat retention instead.

Justin, I just noticed this thread. I’m glad to see that you moved away from the aerogel idea before a large expenditure. I’ve made many iterations of the kinds of syntactic aerogel/silicone foams you described. I have not bought any commercial silicone/aerogel slurries, but I have prepared silicone rubbers containing silica aerogel from granular aerogel and powder, from a variety of silicones  (with and without thinning with hexane), by spraying or casting on fabric substrates in molds, with and without pressure from a manual screw press.

I’m looking for an alternative wetsuit material. I don’t know how you estimated that you could put a thermally meaningful amount of aerogel-imbued silicone rubber on a light fabric substrate for 4 ounces per yard. Nothing less than ten ounces per yard is possible, and that’s for an undetectable amount of thermal insulation. Your tent would only be perceptibly warmer than a conventional tent if the material weight exceeded 20 ounces per yard. This has been covered in past BPL threads. Richard Nisley reported that, per unit weight, down is roughly 52 times warmer than pure silica aerogel, and probably 100x warmer than an aerogel/silicone composite.

I think the material you’re looking for is polyimide aerogel, if you need your insulation to be very thin. Polyimide (Kapton) aerogel will be in most of the durable goods we use in a few years. It is already in use by a couple of garment manufacturers.

I’ll post some images of a few of the materials I fabricated.

This coupon had a 1:1 gravimetric ratio of silicone to silica. It is one that used a low-viscosity silicone and higher pressure, and the silicone infiltrated the aerogel particulate. This sample is dense and rubbery.

This coupon was cast on a substrate of nonwoven nylon gauze.

This one was made with a 1:1.6 ratio of silicone to silica aerogel. At this proportion of aerogel, it is crumbly and not robust enough to use without encapsulation that would defeat the purpose of using the silicone binder.

For tent wall insulation, it is hard for me to imagine doing better than down. Even a very clever, meticulously fabricated multilayer IR blanket (Neoair-style), using very thin metallized films (thinner than 12 um space blankets) and very little glue, wouldn’t beat plain old 800-fill down by very much, and it would be much more fragile, more expensive, it would be very crinkly and loud (particularly in wind), and it would render the inside of the shelter pitch black in the daytime. Remember, also, that bare metallized films lose their metal over time when exposed to environmental insults and handling, so the article will have a lifetime decline in R-value, if it doesn’t tear before that curve is observable.

Silicone/silica aerogel composites have been studied, and a literature search turns up a fair bit of research. The military tested it for wetsuits and found it inferior to neoprene for warmth (I think it can be improved), and their numbers show that, by weight, it is a fairly poor insulator. It is only worth investigating for wetsuits because neoprene is compressible (cold at depth) and very sensitive to UV light. Silicone/silica aerogel composites are almost incompressible and almost immune to UV rays. I just mention these studies because there are similar studies about many combinations of fancy materials, and their accessibility (the literature) could save you money.

I think the tent wall application doesn’t really present unique challenges to insulation design. It is essentially the same cohort of design challenges as a sleeping bag. Criteria for weight, moisture management, and thermal properties are about the same for both applications. So, all of the behemoth body of research and discourse on sleeping bag insulation is applicable to your purpose. If an insulation material seems like it would be poorly suited to a sleeping bag, it would probably be poorly suited to an insulated tent, and for the same reasons. At the end of the design process, I think the same material will emerge the winner: down.

Colin my own observations have been that it can be the exfiltration of warm air that makes the big difference in simple double walled tents, those tents with the more tightly woven and/or heavier inners were much warmer that those with the lighter finer and looser fabrics.

Many decades ago in the Lakes District in the UK I had the opportunity in a winter fixed camp to experience the differences between a series of old style Vango tents

All were Force10 4 man tents but in each iteration of that genre, as the tents got heavier they got warmer, the warmest iteration was the unit with the full weight cotton outer and inner with the addition of a LW synthetic frost liner

I’m wondering then how a down blanket liner would handle the internal condensation as the moisture hit the dew point inside the down layer.

This is why I mentioned the use of the Thinsulate blanket in my early  response post

Hi, Edward. I am convinced of the benefits of insulated tents. Your story about being warmer in some tents than others sounds like a typibycal experience in tents of those kinds. A small insulated tent is a nice, albeit very heavy, luxury. My ex-wife worked for about two months in an insulated lab tent in the field at a remote lake in Antarctica. I string up my oversize quilt inside my single-wall shelter to make a cozy little insulated “inner tent.” It works great. With the right drape of the quilt at the head end, I can adjust the temperature/humidity (not independently) and maintain it in my little cave without getting an abnormal amount of insulation weight gain (I measure every trip), unless I spend three days completely sealed up in it during a snowstorm at Spicer Lake. Then it will be damp. A Thinsulate quilt would be heavier than down but it (or other polyester or polyolefin insulation) might dry faster or maintain more of its insulating value at a given condensation burden than down. I don’t know. It would be a good test.

So am I Colin

I am waiting on a double hip replacement so I didn’t get out this Southern winter but next ski season I will again be base camping near the ski resort I have the seasons pass for.

Not exactly an UL set-up tho but it isn’t a long pulk haul in either.

Australia has very damp winters, temperatures seldom down to where the air drys out so I will be using synthetic insulation, although the old fashioned woollen blankets are cheap and effective if they get sodden and then freeze up I will never be able to get them dry again with the small sized stove I am building

I will start a DIY thread if needed as soon as I accumulate all of the materials I think I need for the project, the biggest problem being to source cheap bulk insulation if I need to purchase new