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  #1  
Old 03 May 2009, 04:28 AM
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snopes snopes is offline
 
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Glasses Your glasses won't fog if you walk backwards

Comment: If you wear glasses and walk in to a warm building from the cold
your galsses fog up. If you walk in backwards they don't. Is it true
that they don't fog up?

I've heard this one on the radio and read it many times. I copied this one
from a message board, it comes with a tiny guess at an explanation :

Over the past few days I have been in and out on various occasions, and
often the glasses fogged up enough that I couldn't see anything. Taking
them off is not an option because I see even less through the blur.

Finally today, since I am known for doing weird things anyway at times, I
decided to try this out. I came in forward as I usually do, and my glasses
began to fog up. I immediately went back outside until they cleared, and
came back in - "backwards"! After trying it a couple times I am convinced,
walk into the house backwards, and your glasses don't fog up.

It works, and I don't have the answer either, unless it has something to
do with the warm air hitting the inside of the glasses first. Try it, but
watch out for the dog or cat.
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  #2  
Old 03 May 2009, 05:04 PM
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Latiam Latiam is offline
 
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It matters whether your glasses are plastic or glass. Also how think they are.
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  #3  
Old 05 May 2009, 09:26 AM
BamaRainbow BamaRainbow is offline
 
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So, it's worse to see things in a blur than it is to walk backwards and possibly trip over or run into something?
This is a great way to be enshrined as a recipient of the Darwin Awards if you're trying to walk backwards through a parking lot to avoid your glasses fogging. (Not coincidentally, I wear glasses and have had to deal with them fogging up--especially on hot and muggy days when I've been running the AC in my car and I get to work, where I have to cross through a fairly sizable parking lot. I find it's a hell of a lot easier to just pull my glasses off and walk to the building. I've got pretty bad vision but I can still make out something the size of a car. But NEVER would I consider walking backwards through the parking lot just to test this theory.)
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Old 05 May 2009, 11:11 AM
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llewtrah llewtrah is offline
 
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I have tested this at home walking into and out of a steamy bathroom. All I found was that they fog up slightly faster walking forwards, probably through hitting the steam sooner. Walking backwards, one's head has a slight windbreak effect with the glasses being in the lee of the windbreak, but once you're right inside the steamy atmosphere you loose that effect and they fog up.

If repeating these experiments in your own home, I recommend removing any pets (and possibly small children) from the immediate area.
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  #5  
Old 05 May 2009, 11:32 AM
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chocolate kisses chocolate kisses is offline
 
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I just wipe my glasses with a tissue or the corner of my shirt to get rid of the fog. You mean I could walk into the restaurant backwards to avoid it altogether! What was I thinkin'!! Much better to look like a doofus than just clean off the lenses real quick.
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  #6  
Old 05 May 2009, 11:37 AM
Shadowduck
 
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Quote:
Originally Posted by snopes View Post
I came in forward as I usually do, and my glasses
began to fog up. I immediately went back outside until they cleared, and
came back in - "backwards"! After trying it a couple times I am convinced,
walk into the house backwards, and your glasses don't fog up.
It sounds to me like (s)he may have walked in and out enough times that the lenses had chance to warm up. That'll stop them fogging, but I don't think it's particularly sensitive to your direction of motion!
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  #7  
Old 04 September 2009, 03:29 PM
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DawnStorm DawnStorm is offline
 
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Glasses

I think I'll just stick with an anti-fogging cleaner.

Dawn--don't try this with a car!!--Storm
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  #8  
Old 04 September 2009, 03:54 PM
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Eddylizard Eddylizard is offline
 
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Quote:
Originally Posted by BamaRainbow View Post
So, it's worse to see things in a blur than it is to walk backwards and possibly trip over or run into something?
I was coming to post almost the exact same thought.

In a blur or foggy glasses you can at least see something in your direction of travel. Walking backwards you can see precisely nothing. Well unless you happen to be an owl I suppose.

Yesterday, I went out in the daytime, and only took my prescription sunglasses and not the untinted ones as well, cos we were "not going to be out for long (TM)" As it turned out, we got back to the car well after dark, and I could see next to bugger all with or without, and in the badly lit parking place I fell base over apex on a small step I didn't see.

I cannot imagine however this would have worked out better for me if I'd been walking backwards.
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  #9  
Old 04 September 2009, 04:20 PM
Singing in the Drizzle Singing in the Drizzle is offline
 
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I use to try this when I was young and started to wear glasses. I seams to work for a small change in temperature, say walking into a 70 deg. room from a outside temp of 45 deg. I would guess that walking in backwards slows the transition down a little and gives the glasses a second or two more warm up. The fog on the glasses would have lasted a couple of seconds anyway. So I would just walk in wait about 5 seconds for glasses to clear and continue.

I can tell it definitely does not work when the temperature is around 30 deg. outside and you step into a warm room. It take to long for the glass to warm up.

Trying to remember my physics classes. Water will fog on glass because its temperature is at or below the dew point. The farther below dew point the faster it will collect on the glass. The more moister in the air the faster it will collect as well. Once the glasses temp. is above dew point the fog will evaporate again. Speed evaporation depends on amount collected, room temp., dew point/relative humidity.
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  #10  
Old 04 September 2009, 05:46 PM
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RCIAG RCIAG is offline
 
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Or maybe just switch to contacts if it's at all possible? I know some can't wear 'em for various reasons, but it'd definitely rid one of that fogging thing.
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