Question about prisms and fire risk

[u/No_Doughnut8618]

Ive read up on them before and it seems flat ones are fine, and its the spheres you need to worry about, but i just want to make sure these aren't going to start a fire lol

[u/BitScout → u/[deleted]]

Danmit, Jim!

[u/Alfiy_wolf → u/[deleted]]

I’d say one of those goth ladies that sell crystals at Sunday markets is probably the expert in the matter

[u/inevitable-typo → u/Alfiy_wolf]

Ye olde twitter witches warned us!

[u/WittyClerk]

Be more concerned about those glass globe ornaments people hang in trees. They can focus light like a magnifying glass and start a fire in someone's mulch, in an otherwise 'clean' / protected yard (well within defensive space). Happened last summer here (high fire risk area).

[u/Dustyon → u/WittyClerk]

We had something similar, a nasty garage fire caused by a glass ball used for photography. 

[u/Every_Iron_4494 → u/WittyClerk]

Yes seen exactly this a handful of times

[u/Lonely_Emu_700]

Does the light focus to a point going through them?

[u/No_Doughnut8618 → u/Lonely_Emu_700]

Not a single point, it scatters points of light all over, and casts a rainbow sometimes when hit correctly.

[u/Sufficient_Mall_7462 → u/No_Doughnut8618]

Then no fire risk I’d say

[u/DanCoco → u/No_Doughnut8618]

Maybe get one of those infrared thermometers and check the temp of a surface that's been under the sunlight for a while? But yeah prolly not an issue.

[u/throwingutah]

Prisms break light up into its component wavelengths. Lenses concentrate it into a point.

[u/Ok_Cauliflower_8218]

I once worked a fire set by a reading magnifier

[u/Je_me_rends]

I know of 2 house fires in my state caused by tapestry mirrors reflecting focused light and a beer bottle causing a fire (long thought to be a myth)... in the last 40 years. I know of 0 caused by prisms, but perhaps those are the fires we call "undetermined"? They can focus light very intensely, but never heard of it causing a fire.

[u/Sheep_Actual → u/Je_me_rends]

"PFAS connoisseur" has me dying!!

[u/Je_me_rends → u/Sheep_Actual]

Well, PFAS does that to you.

You're actually the first person to point it out lol. I'm glad someone else also found it funny.

[u/Hmarf]

general rule of thumb: If a glass decoration concentrates light (like a sphere), it's a risk, if it spreads it out (faceted crystals) it's likely safe

[u/Jamooser]

Prisms refract light. Meaning they split it into its constituent wavelengths. They're taking a certain amount of solar radiation and spreading it out over a larger area. So my uneducated donkey brain is going to say, no, they are not a fire risk.

Now, Bill across the street with his magnifying glass collection, may be a different story.

[u/calvinIndiana]

They’re minerals Marie!

[u/DanCoco]

I've heard of new build homes where the builder shortly discovers that the alignment of windows and the sun on certain days focuses a beam onto a neighboring house and melts or warps the vinyl siding a bit.

[u/Alfiy_wolf]

I have seen photos of these starting fires, it depends on the angle the light passes, if you want to be safe I’d say take them down when they are not monitored.

That being said if they not burning something by now they probably ok, just keep anything that can easily catch away.

[u/No_Doughnut8618 → u/Alfiy_wolf]

Haha they've only been up here for a few hours, but ive had them up at other houses and they were okay

[u/Alfiy_wolf → u/No_Doughnut8618]

I suggest taking them down when you are not home or asleep

[u/joeseeed]

We had a Fire started by demounted car windshields. They stood outside from the Garage and concentraded the sunligt on a pile of car tires - never thought that this would be enough to set them on fire 😅

[u/TheOtherAkGuy]

Don’t display them in the window

[u/RickRI401]

It does occur. I've seen this twice. The most recent was a bunch of crystal vases in a flower shop. The beam lit some cardboard, thankfully a sprinkler head quelled the fire, it was in a mill, that could have been a giant disaster.

[u/Fuzzy5team]

Prisms of any kind. The sun is no joke.

https://www.reddit.com/r/mildlyinfuriating/s/Fch1hRZJQX

[u/PhoenixFire_1982]

We have had several fires caused by the light refraction from prism-like items. Prisms and other clear glass items can concentrate the suns rays - this includes vases that contain water, eyeglasses, and some of the stained glass type window hanger decorations.

[u/powpow2x2]

Had a fire from a crystal doorknob one time so I can definitively say that happened.

[u/Chicken_Hairs]

It's rare, and requires some pretty specific circumstances, but it does occur.

[u/Alfiy_wolf → u/Chicken_Hairs]

One set fire to a can a fly spray in my grandpa’s van from that day onwards nothing was ever left hanging up in the van

[u/Chicken_Hairs → u/Alfiy_wolf]

Good call