Hi,

I just found this on auto blog and seems pretty cool. Not shure whether it will work or not but its worth a shot. This guy removes a dent with a hair dryer and a can of compresse air.

http://www.metacafe.com/watch/...uster/

 

so compressed air dusters become liquid co2 when turned upside down? that doesnt seem right

 

I'm not sure about compressed air becoming CO2 when turned upside down, but I have turned compressed air upside down and for shure it it comes out freezing. Once as an experiment I shattered a piece of glass by just spraying it and then tapping it with my finger nail.

 

why does it do that?

and I think I'll go try it, I have a fairly big dent on my passenger side quarter panel on my crx

 

it looks like someone is pushing on the back of the panel if you watch the top right corner after it pops

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Pockets &raquo;</TD></TR><TR><TD CLASS="quote">it looks like someone is pushing on the back of the panel if you watch the top right corner after it pops</TD></TR></TABLE>

Synics

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by msinsky14 &raquo;</TD></TR><TR><TD CLASS="quote">why does it do that?

and I think I'll go try it, I have a fairly big dent on my passenger side quarter panel on my crx</TD></TR></TABLE> in that case, subscribed

 

Heard about this a couple days ago. Cool idea.

 

when I try this idea, I'll post before and after pics and tell u how it worked or didnt, I'll get to it tomorrow

 

i may try this on the ranger, i'll have to get some air though, but dollar store canned air ftw in case it doesnt work i'll only be out a buck

 

make sure u get compressed air for a computer keyboard, I'm only 17 and they wouldnt let me buy it. they ID'd me for compressed air, I asked the lady why and she said kids blow them up and kill animals with them, I was like WTF!!!???

anyways my dads gonna pick some up for me

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by msinsky14 &raquo;</TD></TR><TR><TD CLASS="quote">make sure u get compressed air for a computer keyboard</TD></TR></TABLE>

Any type of florocarbon compressed air will work. As a Chemist & Photographer, interesgted in both canned air and why it works, I looked in to this phenomenon. The reason for the sub-zero tempature is due to Joule-Thomson effect.

Warning!!!!
**** Science Lesson Ahead ****

The cause of the J-T effect is the forces between molecules (an ideal gas, with no intermolecular forces, would not change temperatures in such an expansion). Because of the weak attractive interactions between molecules, there will be a particular intermolecular distance where the potential energy for a pair of molecules is a minimum (this would be about the average intermolecular distance in a liquid, about one-and-a-half times the molecular diameter). When the gas is expanded, the molecules move farther apart on average, which (by itself) would give the system a higher energy. But if the expansion is done without any addition or removal of energy, the total energy must remain constant (actually, what stays constant in a J-T expansion is a thermodynamic variable called "enthalpy," so the higher potential energy due to the molecules being farther apart is compensated by a lower kinetic energy (which means a lower temperature).

An extreme example of this effect occurs in a vapor-compression refrigeration cycle (like in your refrigerator or air conditioner). At some point in those systems the liquid refrigerant is expanded across a valve to such a low pressure that it vaporizes. This is a large increase in potential energy, which is accompanied by a large drop in temperature.

The amount (and even the direction) of the temperature change in J-T expansion depends on the substance being expanded. For typical gases, expanding from a compressed state to atmospheric pressure causes a modest temperature decrease. However, the preticular florocarbons used in canned air, which are used for their massiave ability to be compressed, causes a massiave decrease in tempature. In addition, the florocarbons used in the product are acctually stored in the liquid phase. When the can is held up right the liquid on the bottom of the can expands and turn into gas, thus pushing the gas out the top. Yet when the can is help upside down the liquid turns into gas floating to the "top" (acctuall the physical bottom of the can) forcing the liquid florocarbons out the nozzle. In thurn the J-T effect happens much quicker and with more dramitc force.



Hope that solved any questions about canned air

 

or the same reason whe i used to take water bottles, poke a hole in the cap, pump it up with air, it would get hot, then when i let the pressure escape, its nice and cold, same with a propane tank witha pinhole leak, so said my chem. teacher

 

I tried this. It kind of worked, but as soon as I ran my hand over the area, the metal popped back in!

 

make it hotter then colder

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by msinsky14 &raquo;</TD></TR><TR><TD CLASS="quote">so compressed air dusters become liquid co2 when turned upside down? that doesnt seem right</TD></TR></TABLE>

yup it really does come out as a liquid, and its c02 in there..that y tha can get cold after spraying to much air.....unfortunatly i figured this out when i was young &gt;&gt;&gt; wut i learn: if u spray a quick mist of the liquid stuff on ur skin it feels "cool" so me like a dumbass like the weird felling and held the bottle on my arm for about 10 seconds and yup sure enough it felt "cool" as the CO2 evaporated but all of a sudden my arm started burning and burning and sting...lets just say tha human skin cant handle the quick change from cold (or frozen) to room temp very well....my skin actually got burned during the process of evaportation, and it hurts!!!....that was at least 10 years ago and i still have a slight blmish/scar from it

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sniggler316 &raquo;</TD></TR><TR><TD CLASS="quote">I tried this. It kind of worked, but as soon as I ran my hand over the area, the metal popped back in! </TD></TR></TABLE>

Yeah if you make it hotter and then colder the molecules will begin to seperate furthur and then snap back into place. The wider the variation the better it should work.


Has any one done any before & after pics?

 

I used a heat gun, so it was pretty hot. Took almost half a can before it froze because it was so hot.

 

i tried it on my rear quarter panel which was dented and creased, didnt do **** to fix it. I guess this crx is going to the body shop, I cant even pop it out at all!!!

 

yeah my dumb *** friend used to huff that **** turned it upside down once lost his tongue dumb *** teenagers

 

we had like 3 people die from huffing that crap when I was in Iraq..


If you want to do this and dont care about the paint you can use a torch and compressed air. All you are doing is shrinking the metal, we use it for oil canning corrections.