Ok so I am going to try to do it tomorrow; the problem is that it has rained the past few days and hasn't been hot enough to do it. I could take the hair dryer, but I don't really want to risk the clear coat.
So provided it is nice and hot tomorrow, I should be able to do it and get some pictures up.

 

i'm still not convinced on the whole "cold water boils faster than hot water thing".

i always assumed you used cold water when boiling stuff because it wasnt softened... (assuming it was from a un-softened hookup sink)

 

I guess the jury is still out on that one. I think the second part of your post is more the reason why than anything else.

But the compressed air thing is true; rapid change in volume = change in temperature.

 

Cant wait for the pics and the results!

 

I can't wait to see the results either. on another note: I have seen much success with Paintless Dent Repair here in Mississippi for cheap. We have had hail storms in the past and probably 50% of the damaged vehicles were able to be repaired via PDR for less than the deductible ($500 in most cases)

 

Little bit of trolling to be done here::::
@nafango2:
actually if you use cold water, it will be more dense... In soft water, this procures a higher concentration of sodium; in harder water this has almost no effect. In hard water, you'll still have the same amount of dissolved solids present regardless of temperature. boiling it for a while however reduces the concentration of the water, and leaves the deposits behind. so the more you boil water away, the more crap you are leaving in the water to be consumed.

for this among other reasons, i bought a filtration system for the entire house, which *naturally* softens the water (instead of how most systems infuse/dissolve salt into the water)


@01 vtec nc:

Actually that couldn't be any more wrong.... really...

It's been proven for HUNDREDS of years that cold water DOES NOT BOIL faster than warm water...
What HAS been proven, is that cold water reaches TOWARDS (but not yet boiling) 100F (boiling point of water) faster than water that is already 90F. Heat transfer is based on (among MANY MANY MANY things) the cardinal difference between the base temperatures...

I.E., 50F -> 100F would have 50 calories times the volume of grams of water to heat up; where the other 90F water would only have 10 of these same units to heat up.
Because of this, the thermal difference is made up faster in the colder water, however as it reaches closer to the 100F temperature - say the 90F range - it actually ends up equaling out.
Most people take either of these two sides:
1 - They just take it for granted, and think that cold water does boil faster...
2 - They think that since water boils at 100F, and the water is colder, it takes longer to heat up....

What most people don't realize is that heat transfers are in no way LINEAR, and often change depending on the medium. In this case we're talking water, so therefor the rate would be equal between both scenarios until similar heat has been achieved; however a piece of metal would rapidly change it's density which would cause it to also change it's thermal transference abilities. In the case of a car, surface area also has a huge play in that. This can be proven by running this exact experiment at home; you'll see that the cold water gets very warm very fast, but they both will boil at the same time (or really damn close).

So if you only want warm water, this is a sure-proof way to get it there fast, but if you want boiling faster it's actually best to start with lukewarm water. Cooling does NOT follow the same principle!!!!

Do some research, it's all over the place!


On the same Accord (no pun intended), your statement about the compressed air is also completely opposite. It is USUALLY VITAL that you cool the area first in order to constrict the molecules in the metal. By heating them, you are forcing them apart, and causing them to move rapidly; thus it "pops" or pushes the dent out.. It is possible, however that doing as you stated would remove the dent, but you also have the unfortunate possibility of making it worse. it depends on the surface tension of the material, size and depth of dent, and the angled direction it's facing.
For evidence of this, take an EMPTY aluminum can and submerge and boil it in water.. then take some very cold ice water and submerge the can in that... The can crushes itself... you want the exact opposite.

And also opposite, is that it works on large/wide shallow dents, not small (which are deep due to the low surface area) ones...


And LASTLY... you're not changing volume of ANYTHING... the statement that follows is the most ridiculous one i've heard in a while:

 

wow, uh, sorry to offend you... Don't know if it required such a flame, but ok. I was not making random claims, I'll give you the boiling water point, there is no definite proof that either way boils faster or if they boil at the same time. As far as the compressed air goes, I did a little research, since it is all over the place; I found this and copied it here:

According to Boyle's law, the pressure exerted by a given quantity of gas increases as the volume of the gas decreases at a constant temperature. According to Charles's law, at a constant pressure, the volume occupied by a given quantity of gas decreases as the temperature of the gas decreases. According to Avogadro's principle, the volume occupied by a gas depends directly on the number of gas particles at a constant temperature and pressure. If all three of these laws are combined, the result is V= R*((nT)/P). R is the universal gas constant which is equal to 0.0821 L*atm/mol K (Kelvin). By multiplying both sides of this equation by P, the equation would become PV=nRT, the ideal gas law. Note: P=Pressure (atm), V=Volume (L), n=number of moles, and T= Temperature (Kelvin)).

So, PV=nRT means Pressure * volume = numberber of moles * 0.0821 * Temperature.


Without getting into too much detail, let's say that temperature is directly proportional to pressure and volume.

When volume (the can) is constant and pressure decreases, the temperature also decreases. Look at it this way: PV=T

For example (omitting the units should avoid further confusion), P= 10, V= 10, T= 100
10 * 10 = 100.

Let's lower the pressure to 8. P= 8 V=10 (again, this is constant), T= 80.
8 * 10 = 80.


The same works in reverse. When the can is a constant size, increasing the pressure increases the temperature.
PV=T
We'll start the with the same ammounts:
P=10, V=10, T= 100
10 * 10 = 100

Let's raise the pressure to 120.
P=120, V= 10, T= 1200
120 * 10 = 1200


On the issue with the dents in the accord: both ways should work equally well, when the molecules are spread apart like when it is hot and you cool it quickly, the molecules will suddenly constrict and "pull" the dent out. It is not going to make it worse because it is going to take more pressure to push the dent in and bend more metal than pull it out and fight the force of unoccupied space.
Apparently you already know how it works when you do it the other way around so I won't go to the bother of explaining it other than the fact that you are then pushing the dent out instead of pulling it.

 

So I did it today, it was not perfect, but it did work for quite a few of the little dents. The dents were really small to begin with; they really just bothered me so sorry if the pictures are hard to make out.
Before:


[IMG]local://upfiles/17119/0DCCC9F77BFE41FA80B9C38298B4AFE6.jpg[/IMG]

[IMG]local://upfiles/17119/D328320DF01F47E3A9998A9BFC899D06.jpg[/IMG]

 

You can see it didn't completely pull out some of the dents, but it did a pretty good job on most of them. My problem is there are like a couple hundred of them across the car and each one takes at least 60 sec to do so do the math

After:

[IMG]local://upfiles/17119/45BF4CEE787644F68365A21451A5C6F1.jpg[/IMG]

[IMG]local://upfiles/17119/D0D1474EB4F1484DB9879F4D82E48D3E.jpg[/IMG]

[IMG]local://upfiles/17119/95E9E8A3AB5149B98C536FAEF6F092DB.jpg[/IMG]

 

Oh and klrspz, I don't know why you felt the need to flame me with faulty information, but if you had done some of the research you are so fond of you would have found quite a few articles, pictures, and even videos of people doing this dry ice dent removal with little to no problems.

Saying that, this is not the perfect solution, klrspz idea of cooling first and then heating might work better for some dents, I don't know, I have NOT done the research and won't make claims on something I don't know. Either way, this method seems to work well with small to medium size hail dents; there was a very small change in the tiny dents, and I didn't have any dents big enough to test the method on them.

Oh and it didn't hurt my paint or clear coat at all, when it got cold, it discolored and I kind of freaked out, but after like 20 seconds it went back to its perfect shine.