Make Your Own Aerogel

Our own [Eliot] dug this one up from the grave. While the recipe has been online for a while, do you know many 10 year olds who made their own Aerogel, that wonderful insulator that’s essentially gelled air? [William] made some(cache) for his science project in 2002. He started with Silbond H5, a combination of ethyl alcohol and ethyl polysilicate. You can get the MSDS after a painless email registration on the Silbond website. After the gel is formed you have to soak it in an alcohol bath to make sure all water has been removed from the structure. Then the gel is placed in a drying chamber. Liquid CO2 is forced into the chamber to displace all the alcohol in the chamber and the structure. Once the the alcohol is gone the supercritical drying phase begins. The temperature is raised to 90degF and the pressure is regulated to 1050psi. At this point the liquid CO2 in the gel structure takes on gas properties (looses surface tension) and leaves the silica structure. All that remains in the chamber is your new Aerogel which is 99% empty space and 1000 times less dense than glass.

Of course, if you’re lazy, you can buy some here.

43 thoughts on “Make Your Own Aerogel

  1. No, no. It very specifically says that “William found,” “William settled,” “William used,” “William did,” “William needed,” “William gave,” and “William increased.” How could you possibly think his parents had anything to do with it.

    There’s got to be a really cool application for this in theatre lighting. I wonder if you can use some sort of dye to make it different colors and presumably it wouldn’t melt and burn out like gel.

  2. Yeah, I’ve got a lot of experience with these science fair projects–the majority of the really good ones aren’t actually done by the students (there’s always a couple of geniuses here and there, of course–they’re almost in the upper grades, though).

    While they’re young, it’s their parents doing everything, but in high school, it usually ends up being a laboratory mentor who basically came up with the whole project and had the student do the majority of the dirty work. And it’s usually people with lab internships who win. . .whatever happened to the true science fair project that’s actually done at home?

  3. nice, i want to use some for my boat. but i can’t afford upwards of 3 8x10ft sheets of it and i really don’t think i can make a steel mold/pressure chamber big enough either. ahh well, styrofoam it is.

  4. @Cahlroisse

    The pictures I’ve seen of aerogel makes it far too close to opaque to use as gel, ideally the color medium is as close to transparent as possible so you remove only very specific wavelengths.

    Plus, a full sheet of gel is only maybe ten bucks at most, so I think the cost would be hard to justify.

  5. What do you think your going to do with it? The novelty would wear off quick. Probably just better to buy some and only be out $20 and a few minutes of your time.
    However, if you find a cool use for something like this then make some SEAgel. It is 10% lighter, relatively easy to make (you can buy a freeze drying machine on E-bay), and it is non-toxic, even edible! The materials are easy to get also. It is made from Agarose,which comes from seaweed. You can get it just about everywhere.
    There must be some cool uses for this stuff.

  6. seagel–sounds awesome! Has anyone actually done it before? Though wikipedia only mentions water, another online source states that you need another organic solvent to distribute the agarose evenly (makes sense–agarose doesn’t like dissolving at room temp. . .but then again, just microwave it. . .)

    I see a lot of applications in lightweight chassis. . .*hint*r/c helicopter*hint*

  7. Though it occurs to me, if a thin sheet of aerogel could be made large enough (6-8 inches square), and was even 85%-90% transmissive (in that it allowed that much light to pass through unmolested), could it be used as a heat shield for theatrical gel? Though I supposed here the primary issue is infrared energy.

    As for that matter, even if you could dye the aerogel, the issue isn’t always the ability of the gel medium to withstand heat, but the ability of the color medium to do so, as evinced by gels that have been burned clear but otherwise undamaged.

  8. @sp’ange:
    From what I understand, areogel is a closed structure, which means it should just reflect sound like a flat surface. Insulation like Owens Corning 703 and 705 compressed fiberglass board is apparently the best stuff for sound absorbtion since it is a dense, yet open structure of fibers.

  9. if a mechanical engineer made some of this, and carefully tested its true tensile strength, s/he could make a very light, fast and aerodynamic bicycle frame. But a lot of safety testing would have to be done because if it shattered it could impale the rider.

    I’d also be interested in its uses for radio-controlled aircraft, if it’s as light as foam, but stronger, there are a lot of possibilities.

  10. this would be horrible for a bike frame. Its far too fragile for this (remember, its basically glass)
    the best use of this stuff is as a heatshield. there is a video floating around of a guy with a 1/8″ sheet of aerogel with crayons sitting on top and heating it with a 3000f blow torch, and the crayons did not melt.

  11. The combination high temperature, pressure and alcohol is not entirly safe, as can be seen from a New York Times story:

    “But supercritical alcohol processing can pose problems. The Airglass Company of Sweden makes aerogel material for use in high-energy physics experiments, and its method of extracting water from gel used supercritical alcohol. But in 1984 a gasket in the company’s pressure vessel broke and vented supercritical alcohol, which immediately detonated. The explosion heavily damaged the plant and injured several workers.”

    So, make sure you do not have any alcohol left when drying.

    1. Carbon dioxide goes supercritical at 70°C, around 160°F.
      Alcohol exchange happens before it’s heated to supercritical. So, a supercritical carbon dioxide drying isn’t all that hot and the alcohol is already gone. You can do supercritical ethanol drying, which is much hotter and admittedly more hazardous if you don’t know what you’re doing, but it’s usually done with carbon dioxide for those very reasons.

  12. The year before, William spent hundreds of hours reading around 100 web sites about aerogel, emailing universities and corporations about the stuff, receiving a handful of samples, including a 4″ disk, touring the plazas in Bakersfield to interview citizens, and preparing his report. For this project, I, his “big brother” conceived the idea of making aerogel at home. I consulted with him about how to design the mechanicals. I had to request the Silbond, because the company would not send it to a minor. I drove him around to the metal surplus yards where they advised him on schedule 80 pipe, fittings, valves, and gauges. Many of these were donated. He acquired the ammonium hydroxide and pure ethyl alcohol from Cal State Bakersfield, though I had to sign for it.

    He made the raw gels and the alcohol baths. I tightened the larger fittings because even with a 30″ pipe wrench pair he was not strong enough to seal them. He did the work of temperature control with both ice in the first stage and hot water in the second. Ice had to be applied a few times each hour, and hot water every few minutes to keep the temperatures first below then later above the required levels. William did all the work at every stage. I, however, also had to loosen the large pipe fittings after the process was completed. Then William had fun spraying the remaining CO2 all over the yard, freezing weeds, and having fun.
    I am not a college graduate, William’s guardian is now 85 years old and lives in a hodgepodge of an old house.
    In conclusion, while we collaborated on the design of the project, and I did the things not allowed for a minor, or that were physically beyond his strength, William did this project. He had technical assistance from the University of Virginia, Aspen Aerogels, U Cal Berkeley, and NASA employees.

    1. And since you are to be commended for mentoring and assisting a young man with overt potential as a scientist or engineer and are too cultured to state the obvious I will stand as your second and say to the churlish masses…..”so there!”
      Rick the unwashed.

  13. Oofrab mistakes the older alcohol supercritical drying with liquid CO2 drying. The temperatures and pressures are vastly different, and the quantities of alcohol involved different by several magnitudes. William did his project in the yard, and the little alcohol in the sample simply evaporated and blew away. There is no danger of such explosions drying aerogel by the CO2 process.

  14. Regarding souond insulation, aerogel is the most effective sound isolation substance known. However, it is extremely expensive to make in large sizes. If you are a billionaire you could afford to isolate a room that way. However, for the best effect the aerogel should be exopsed, and its fragility makes it impractical as a sound dampening wall.

  15. I need this material for several projects but have a modest income. More info is required on fabrication from home. Let us be realistic. Who can use little nickel sized blobs of it? I need real info: what does it feel like? Is it brittle, easily broken, flexible, explosive in a vacuum chamber (air bubbles escaping)? how can I make sheets of it? can it be cut with a blade or grinder? poisonous dust if so? inhalation dangers during fabrication?

    I’d like to line my house with this stuff, but not if it’s gonna take a hundred years to make enough, or if all I get are little blobs I have to super glue together. And how would I hang them in place in the wall hollows, with a simple drill, or do I need a phaser pistol?

    I don’t mean to be rude or an ingrate, but serious minds need to know such things.

    Can it be doped with other chems during fabrication to make it more flexible? Again, toxicity? Does anybody out there know?

    If aerogel is fragile, why are the Israelis contemplating using it as a bullet proofing in vests? They said it the vest is fairly flexible but it doesn’t breathe well and gets unbearably hot inside.

    I’m getting differing opinions. Need facts from someone who’s touched it.


  16. I believe that a ten year old could accomplish such a feat, because I am only 13, and have developed a formula to calculate the distance to the moon compared to the radius of the earth, and I have a made a break-through discovery on the study of perfect numbers, a study which has stumped the world’s greatest mathematicians including Euclid and Mersenne for centuries!

  17. question. we’re now doing a research on aerogel. instead of silica, we used agar (agarose). we got the concept from seagel but the process we used was that of the ten year old (william). the problem is we tried so many techniques on the supercritical drying but the structure we got collapsed and shrinked. how can we make the pressure rise while lowering the temperature? are we going to continue flow the Liq CO2 and lock all the valves while lowering the temperature? is that possible? the last time we tried it, the pressure still decreases. how can we make the pressure atleast constant.

  18. I can probably offer some insight, as I’ve worked with aerogel.

    Aerogel is typically very transparent in the visible and infrared, less so in UV due to Rayleight scattering.

    Aerogel is like florists foam to the touch, and you will leave nasty finger prints on it just by touching it, if you press hard enough you will make a dent, and harder it will break. It is very brittle, if dropped from even a small height it will shatter. Would make a terrible bike frame.

    Aerogel is no more toxic than glass, you should avoid inhaling glass dust and eating it although it probably wouldn’t kill you.

    Normal aerogel is hyrophillic and gets destroyed when contacted with water, however it can be made hydrophobic with post-processing or with a different precursor chemical

    Aspen Aerogels add in some plastic or something to make it bendy, and have some cool names for it like Pyrogel!

    Aerogel is not a closed structure as it has open pores through which gas can diffuse. I think it takes ~1ms for gas to diffuse through 1mm of aerogel.

    I don’t think the child was achieving anything that NASA could not, as this was the first way in which aerogels were created. Nasa have created massive blocks for comet dust collection.

  19. It’s totally possible to build a supercritical dryer if you know what you’re doing. I did it when I was in high school back in 1999. That said, I am impressed by any 10-year-old that has demonstrated that level of knowledge to figure out how to put all the chemistry, engineering, and process details together.

    Anyways goes into depth on how to make aerogel and build a useful supercritical dryer:

  20. Although areogel was just trumped not to long ago by a lab that invented what they called SEAgel, which is even lighter (making it the lightest solid known to man… it’s actually lighter than straight nitrogen gas!) You get that by freezedrying agar (basically skirting around the other side of water’s phase diagram.)

  21. i gained info of preparing or doing sol-gel is very expensive. Al though some produce it which about $2 per cm3… But its use is going to take over all in near future…

  22. Wouldn’t a block of aerogel be a good diesel particle filter?
    I understand it can stand up to 1200°.
    City traffic diesel exhaust temps are around 250°, max is around 650° when the filter regenerates. Son that would be within it’s specs.
    I wonder if it would let exhaust gases through.
    Prices per m² seem to refer to sheets. Might need cylindrical shapes of 60-90cm though.

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