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An Ikea Bowl Has Been Setting Things on Fire

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Re: An Ikea Bowl Has Been Setting Things on Fire

#111

Post by vanderZwan »

captainmuon wrote: post #64
vanderZwan wrote: post #51

Earlier quoted context omitted.

Well, melt the paint on cars. I suspect that the amount of energy required to melt an entire car would be quite a lot more than even a skyscraper worth of surface area could gather from the sun. > This isn't the first time Viñoly's architecture has raised eyebrows as well as temperatures: His Vdara Hotel in Las Vegas has been criticized for directing sunbeams onto the swimming pool deck that are hot enough to melt pl…

> I suspect that the amount of energy required to melt an entire car would be quite a lot more than even a skyscraper worth of surface area could gather from the sun. Actually, https://en.wikipedia.org/wiki/Solar_furnace ... The furnace in Odeillo, France can reach up to 3500 °C, and it's cross section is just about 50x50 meters. Of course, your typical skyscraper won't create those temperatures accidentially, but if…

Wow, TIL. Thank you! Good that the building doesn't have a perfect focal point then!

Re: An Ikea Bowl Has Been Setting Things on Fire

#112

Post by cr0sh »

logfromblammo wrote: post #93
sswaner wrote: post #45

Earlier quoted context omitted.

The Boy Scout handbook (1980's version) had an aluminum foil solar oven design for cooking a hot dog. It was a version of that psychology test of putting marshmallows in front of kids. The patient scouts got a cooked hotdog in about 45 minutes - on a bright summer day. I ate a raw one after about 10.

Unfortunately, my kids already know from watching How It's Made that most wiener-type sausages sold in the US are fully cooked at the factory, and when you "cook" them at home, you're just heating them up. One would just eat it without bothering with the foil for even one minute, and the other doesn't eat hot dogs at any temperature. I remember, as part of a wilderness survival challenge, being told to eat some break…

> most wiener-type sausages sold in the US are fully cooked at the factory

I don't know if I would say most, but some may be.

From my experience, hotdogs (and other sausage products) typically contain a ton of what is known as "pink curing salt" (aka "Prague powder"):

https://en.wikipedia.org/wiki/Curing_salt

It's dyed pink to prevent confusion with common table salt (and it isn't the same as the "pink artisan table salts" you sometimes see, either); in fact, the amount used in curing sausage and other cured meats is actually very low in proportion.

Such cures are used for ham and bacon making, too. The actual meat isn't cooked in any manner, but is perfectly safe to eat - though technically raw. In the case of hame and bacon, the meat (after curing) will usually then go thru a secondary smoking process, which also tends to dry out the outer layer of meat, further protecting it from bacterial intrusion.

Re: An Ikea Bowl Has Been Setting Things on Fire

#114

Post by Camillo »

jefurii wrote: post #101
Freak_NL wrote: post #12

The same phenomenon occurs with glass spheres. If you think about it it is obvious enough (most people are familiar with how a magnifying glass concentrates the ray of the sun in a single spot), but it is something people tend to overlook when employing glass spheres as elements of your interior design — e.g., glass door knobs, large marbles, and decorative knick-knacks (which people have a tendency to place on their…

> The same phenomenon occurs with glass spheres. Also clear water bottles (filled with water). In 1991 there was a brief period where homeowners all over Japan were putting clear PET bottles (PolyEthylene Terephthalate) at the edge of their properties because it was asserted on some talk show that the sparkles would keep animals away. This ended abruptly when a series of fires were started by the bottles.

Some people still do it. I've seen it this year in Akasaka.

Re: An Ikea Bowl Has Been Setting Things on Fire

#115

Post by cr0sh »

logfromblammo wrote: post #93
sswaner wrote: post #45

Earlier quoted context omitted.

The Boy Scout handbook (1980's version) had an aluminum foil solar oven design for cooking a hot dog. It was a version of that psychology test of putting marshmallows in front of kids. The patient scouts got a cooked hotdog in about 45 minutes - on a bright summer day. I ate a raw one after about 10.

Unfortunately, my kids already know from watching How It's Made that most wiener-type sausages sold in the US are fully cooked at the factory, and when you "cook" them at home, you're just heating them up. One would just eat it without bothering with the foil for even one minute, and the other doesn't eat hot dogs at any temperature. I remember, as part of a wilderness survival challenge, being told to eat some break…

> that the tinder had KMnO4 in it, and the arrow popped a hidden balloon with some glycerol

For those that don't know, KMnO4 is also known as potassium permanganate:

https://en.wikipedia.org/wiki/Potassium_permanganate

As noted in that wikipedia article, when combined with glycerol or other glycerin containing products (like automotive antifreeze) it can also be used as a fire starter. It can be easily found online or at home improvement stores, as it is sold for water softening and filtration purposes.

Grant Thompson ("King of Random") documents how to make a survival fire starter kit using this knowledge:

https://www.youtube.com/watch?v=ja_6Yin9JuM

In short, keeping a bit of potassium permanganate in your car with you, should you get lost and don't have another source of fire making with you, might be a wise thing (then again, if you know anything about automobiles, there are tons of ways to use parts in them for starting a fire).

Re: An Ikea Bowl Has Been Setting Things on Fire

#116

Post by agumonkey »

cr0sh wrote: post #108
agumonkey wrote: post #57

Smiling hard, I was looking for a solar concentrator online when I should have gone to the nearest IKEA store. ps: a video that go well with the PrimitiveTechnology channel

If you live in the US (or you know someone), and you have bulk-trash pickup (or can scavenge otherwise) - look around for an old 40 or 50 inch rear-projection television. All of them use a large fresnel lens for the screen (they also have an interest lenticular lens as well - but that isn't as useful due to it's short focal length). This lens, properly mounted, is capable of melting glass, rock, steel, etc. IE - if y…

Yeah I know, I've seen these dozens of time on youtube[1], but there's not a lot of these TV around anymore; or I need to find a real landfill.

A large fresnel lens is my most wished prize right now, I consider looking into manufacturing one.

[1] to recycle glass, metals etc, maybe produce some cute things or just to ease trashing (bins won't contains large empty bottles, but nice pellets)

Re: An Ikea Bowl Has Been Setting Things on Fire

#117

Post by cr0sh »

ythn wrote: post #90
dekhn wrote: post #74

Earlier quoted context omitted.

I can set a piece of cardboard on fire with visible flames in a few seconds. I carry a small fresnel lens, https://www.amazon.com/3-Pack-Credit-Card-Pocket-Fresnel/dp/...

I still maintain that it is much more difficult to start a fire with a lens or mirror than people seem to think. Post a video of using your fresnel lens on different material types (paper, cardboard, wood, pine needles) and see how quickly you can get a visible flame. I'm betting you won't be able to easily get a visible flame on most materials you try.

> I still maintain that it is much more difficult to start a fire with a lens or mirror than people seem to think.

I'd have to agree with you. When I go hiking, I carry around 3 or 4 different kinds of "fire making" things, just in case I need them for any reason. I also practice with them on occasion to know what to do when I really need them.

It isn't easy to start a fire from scratch. It takes a bit of work, a bit of knowledge, and a ton of patience and perseverance. If you don't have any of that, you'll have a hard road ahead of you.

Even using good tinder plus magnesium bar shavings and a flint striker isn't as easy as you'd hope. In fact, it can be very frustrating. But once you get it going, it's very satisfying.

This is why I also carry a Bic lighter, strike-anywhere matches (in a waterproof container), esbit tablets, and a fresnel lens - all as backup fire sources.

Re: An Ikea Bowl Has Been Setting Things on Fire

#118

Post by Florin_Andrei »

stcredzero wrote: post #97
Freak_NL wrote: post #12

The same phenomenon occurs with glass spheres. If you think about it it is obvious enough (most people are familiar with how a magnifying glass concentrates the ray of the sun in a single spot), but it is something people tend to overlook when employing glass spheres as elements of your interior design — e.g., glass door knobs, large marbles, and decorative knick-knacks (which people have a tendency to place on their…

But because the risk is so low (it doesn't happen that frequently) many people are completely unaware of the phenomenon. Also, people can't apply what they were supposed to learn in high school physics. It's not only Brazil that has this problem: http://v.cx/2010/04/feynman-brazil-education

> Also, people can't apply what they were supposed to learn in high school physics.

Well, it's very rare and therefore you don't think about it.

I make telescope mirrors, so I can't be accused of being unaware of the laws of optics. Yet until now I never thought about crystal balls (heck, even acrylic balls) as a potential fire hazard inside the house.

Re: An Ikea Bowl Has Been Setting Things on Fire

#119

Post by logfromblammo »

cr0sh wrote: post #112
logfromblammo wrote: post #93

Earlier quoted context omitted.

Unfortunately, my kids already know from watching How It's Made that most wiener-type sausages sold in the US are fully cooked at the factory, and when you "cook" them at home, you're just heating them up. One would just eat it without bothering with the foil for even one minute, and the other doesn't eat hot dogs at any temperature. I remember, as part of a wilderness survival challenge, being told to eat some break…

> most wiener-type sausages sold in the US are fully cooked at the factory I don't know if I would say most, but some may be. From my experience, hotdogs (and other sausage products) typically contain a ton of what is known as "pink curing salt" (aka "Prague powder"): https://en.wikipedia.org/wiki/Curing_salt It's dyed pink to prevent confusion with common table salt (and it isn't the same as the "pink artisan table…

Those that aren't cooked are smoked. 100% of all frankfurters, wieners, hot dogs, and bologna intended for sale in the US is safe to eat cold, as long as it has been kept sufficiently cold since it was packaged.

If it wasn't cooked or smoked, you can't call it by those names.

The most common [pathogenic] contaminant is Listeria. This would be on the surface, so if you want to be strict about food safety, you can just drop your cold hot dogs in boiling water for a few seconds before eating them. But if you're really that concerned about food, why are you eating sausages at all?

Re: An Ikea Bowl Has Been Setting Things on Fire

#120

Post by tekromancr »

thesz wrote: post #70

Can't help myself: https://www.youtube.com/watch?v=uJuuFLo1a84&t=252s Getting fire with the spoon (!) in Siberia's (!!) Winter (!!!). The sun light is not very bright at that time, just for a note. Sun is about couple tens of degrees above horizon and (infrared) light mostly caught by the atmosphere.

"Sure, it's cold—but to a fire, everything is cold" https://what-if.xkcd.com/155/
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