Aerogel sleeping pad

[Colin Krusor]

I obtained a good sized piece of Aspen Aerogel's Spaceloft 6251 that was left over from a research project at the lab where I work, and I plan to make a sleeping pad from it. I may use just the aerogel blanket, or I might try putting aerogel panels in sheet of EVA foam. In any case, I've had trouble finding a good way to get the dimensions of my "footprint" when I sleep. I had someone draw my outline on butcher paper as I lay in several positions, but I also thought about making a multi-piece sleeping pad that could curl up when I curl up (see crude MS Paint image below). Does anyone have any advice on pad shape?

[Mike Barney]

Hey Colin, whatever you do, there are many of us that would be very interested in how well it works, in particular how robust the material is when a dynamic load is applied.

[Colin Krusor]

Mike,

I'm eager to see how it performs as well. Since I learned of the development of aerogel blankets at Aspen several years ago I've fantasized about having some to experiment with. I couldn't believe my luck when about twelve square feet of it was left over after a cryo project at my lab.

This piece is 6mm in thickness and contains no carbon (it's white). It produces a prodigious amount of fine dust and must be handled with gloves and a mask. It isn't compressible like foam. It feels like very firm, dense felt. It is very dense (about twenty ounces per square yard), and I think the 3mm version (which I wish I had) would be much more practical for lightweight sleeping pads.

I plan to encapsulate small, palm-sized panels of it in mylar (shrinking the film with a heat gun) and install these panels in cut-outs in a sheet of EVA foam. Hopefully the relatively incompressible aerogel will support my body and reduce the compressive load on the foam, too.

Data on this material (Spaceloft 6251), as well as the others produced by the same manufacturer, can be seen at http://www.aerogel.com/products/overview.html

[Steve Smith]

Hi Colin, this is very interesting. Have you had any luck?

I wonder if a 1mm sheet would be enough, perhaps treated with something to eliminate the dust hazard and then sandwiched between 2 other thin layers. It could be the size and shape of a normal 3/4 pad.

Steve

[Colin Krusor]

Steve,

That's a good suggestion. My drawing board turned from a few scribbles on some graph paper to a convoluted mess of dozens of far-fetched ideas. I found that the piece I have can be peeled into five or six separate layers, each about 1mm in thickness, so I have a lot more design flexibility than I first thought. A good deal of research has gone into the design of lightweight, flexible insulation blankets for use around underwater pipelines where compression by hydrostatic pressure is a problem. That application is a good model for the challenges in sleeping pad design, I think. There are plenty of articles available that discuss underwater pipeline insulation blankets made of aerogel, EVA foam, urethane foam, syntactic silicone foam (filled with glass microballoons), and other materials.

EVA has low density and is waterproof and tolerates abrasion well. The aerogel blanket is dense, fragile, expensive (if you didn't obtain it for free), and complicated to use. For simplicity, durability, and price it can't beat EVA. The aerogel is a much better insulator than EVA per unit volume, but thinness isn't a requirement (or desirable) for sleeping pads. It could achieve better insulation per unit weight, but only in evacuated (less than 10 torr) envelopes. Without a vacuum the aerogel is hardly better than EVA per unit weight. I thought about using a small vacuum pump and a heat sealer to make thin, flexible aerogel vacuum panels. They would be an excellent insulator (almost as good as hard vacuum, like a dewar), but they would require valves for occasional re-evacuation, they would be fragile, and it's an expensive project.

So, I haven't decided yet how to use this stuff. Your sandwich idea is a good one. Other ideas are welcome. I'll post any new developments.

[Steve Smith]

I think that for a sleeping pad, the insulation to volume ratio is quite valuable. Pads take up a lot of space in your pack. A pad that packs to the size of a book would be excellent.

A 1mm sheet could also be good for insoles (on snow or ice); and for gloves (most gloves are very bulky, sacrificing manual dexterity).

Also, EVA melts easily. Aerogel can withstand cooking temperatures. Some usefulness there?

Steve

[Colin Krusor]

Steve,

You have excellent ideas. I hadn't really thought about the benefits of a pad that could fold like a road map. Puncture of the film encapsulation around the aerogel is still a concern to me, but I guess that risk could be ameliorated with a bit of 1/8 inch foam on the bottom.

There are insoles available that incorporate aerogel. I think they're sold under the Toasty Feet brand and the aerogel they use is Aspen's Pyrogel 2250. Aerogel glove liners have been used in dry suits for cold water diving, and I think Burton makes a mitten called the Pinnacle Plus that incorporates small pieces of aerogel blanket. Pacific Outdoor Equipment makes a sleeping pad that boasts small aerogel panels, but it also has gel-filled panels, weighs almost two pounds, and costs $150.

I did sketch a few ideas for glove liners and insoles, and I think I might try to tackle those before I attempt the sleeping pad (if I can settle on a design). I agree that in those applications the high volumetric insulation value of this stuff is a benefit. I thought about applications to cook pots and stoves, too, as you did, and I think on long trips where no dry fuel exists for a small wood stove (where fuel has to be carried), a small amount of aerogel insulation might save enough fuel to provide a net savings in weight. It would probably only be worthwhile on the longest trips when fuel weight is considerable. In small woodgas camp stoves I guess a little aerogel insulation could aid in gasification by slightly increasing the temperature in the anoxic part of the fire tube.

[Steve Smith]

I think your concerns about the pad puncturing are very valid. Maybe that is the reason it isn't used much in contact with the body. Also why I think it's important to seal the surface of the blanket with something. But even then, a lot of people – perhaps me and you included – will be put off by the health risk. Thanks for the compliment, by the way ;)

Steve

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