Hail damage

So I just bought a 2001 Accord Sedan; I got a great deal on it partly due to the fact it had hail damage across the hood, roof, and trunk. The damage isn''t terrible, and I honestly could live with it because nobody really notices unless I point it out, but I would like to get them out eventually.

Does anyone know a cost-effective way/company that does this sort of thing? I will try to post some pictures later, I live in Charlotte, NC so anyone that knows about anything around here that would be great. I would like to keep it under $500 if possible, but I do really want a good job so if I need to spend more, I might just have to suck it up.

paintless dent repair (PDR) is NOT cheap.... IMO, it''s rarely worth it..

Last I was quoted it was $75-120 per dent, depending on the size and location. Most of my dents I was told could NOT be removed via PDR and required a new panel/door-skin (it was on some of the rigid lines along the side... worst thing honda could have done is put a ridge right where car doors hit :( )

How big are these dents? I''ve seen some videos about using compressed air cans to pop out larger ones: http://www.youtube.com/watch?v=miNykNl-0NM&feature=related

Could also try somethin like this? http://www.youtube.com/watch?v=SdVpvL_FpoQ
don''t know what kind of results this kind of product really yields...

a friend of my dad said he once used a plunger on one.. seemed ghey, but who knows.

They are really tiny little dents, the largest ones are maybe half and inch across and not very deep at all. I really am the only person who notices it, but I am anal ;)
There are probably a couple hundred dents across the hood, trunk and roof.

I witnessed a friend''s truck having the hail dents removed with liquid nitrogen. This was a pro shop that specialized in that technique and it was 100% successful.  Might be worth looking in your area for that. 

Hmm, I would almost be scared to try it, though if it works...

I had never heard of it but it did work without question so ???????????????

Have any of you seen the trick of heating up the dent w/ a hairdryer and then spraying a can of compressed air upsiude down on the dent immediately afterwards?  Saw it on youtube and would like to know if it works bc i have a few dents.  Does anyone know if it would harm the paint?

The compressed air trick would be the exact same as using the dry ice. I did a little research and found out why: when the metal heats up, the molecules start moving faster (high school chemistry anyone? it''s been a while for me...) when you cool it quickly by either using dry ice or creating a pressure change in the compressed air which makes it super cold, it slows down the molecules almost instantly which causes them to bond together basically squeezing the dent out.
I watched a video of it in action and read up on it a bunch. I''m gonna try it sometime soon so I can be the guinea pig for you guys. I''ll post some before and after pictures once I do it. By the way, apparently it only works on smaller hail size dents, it doesn''t work as well with the larger ones. 

oh, and the purpose of heating it up first just makes the reaction when you super-cool it more extreme so there is a greater chance the dent pulls out. Same reason cold water boils faster than hot water.
You don''t need to have the hair-dryer, my good old 100 degree NC sun should be plenty for me; I don''t want to risk damaging the clear coat with a hair dryer.

I would LOVE to see before and after pics.  I desperately need to get a few dents out and if it works I will try it out!

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:

quote:

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

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[link=http://www.answerbag.com/q_view/37186#][/link] 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:



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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:


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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.

Actually, I didn''t flame you, i was pointing out your inaccuracies... there''s a difference... I''ll try to keep this to pointing out facts and NOT flaming

Also, you didn''t offend me or anyone, I just wanted to point out some facts...

In regards to the volume thing, I misread what you were talking about; i thought you were talking about the volume of the panel on the car... in that respect, you have to understand how silly that sounds... my bad.

Anyway, I didn''t flame you with faulty information in fact, it''s science...

It''s not only more logical to consider that cold water can''t boil faster, but is indeed scientifically proven countless times that it is in fact a FALSE CONCEPT that cold water boils faster than warm... It''s proven, over and over.. You can easily try the experiment at your home..
You can even invest tens of thousands of dollars into thermodynamic tools it would require to mathematically prove it as well... Not only have I done it with such high-end equipment, but you can find the information free-flowing on the Intarwebs. This is called Physics 101, and is usually the first or second lab experiment you do after class... Something along the order of "Watch Mr. Wizard" type difficulty.

In Thermal Physics (thermodynamics, kinetics, etc) [which my minor in Physics happens to be specialized in; as well as E&M], heating a cooled item and cooling a heated item are completely different, and require completely different things to occur. Sure the end result is technically the same in terms of the thermodynamics, but the kinetics and stat. mech''s behind it are not even close in magnitude. You can''t say that heating up water to a gas and bringing it back to water are near the same thing, there''s so much going on there. There are so many statistical things you have to consider... AND, you have micro and macro states that define what''s truly happening at any given moment (think instant velocity). It could certainly play a big role in terms of how effective or damaging these techniques could provide... However without proper equipment, specific stats at hand, and the time/effort to put into it you MIGHT be right that it doesn''t matter in the order... However, in the right scenario, it means all the world.

I not only have a Majors in MATH, BUSINESS, and COMPUTER SCIENCE, but I have a minor in Physics. I''m not trying to be a dick, nor am I trying to be difficult; but apparently you were butt-hurt about the facts I presented... So much so that you thought it wise to present a formula. I know you didn''t come up with it on your own and copy/pasted it, but the original author remove parameters from it without any stated assumptions.. And BTW in this equation, PV ≠ T; but rather PV/nR = T; there''s a HUUUUUGE difference there. I''m not an engineer, but they''d surely argue that all day and night with you.
Also, that proves it to be non-linear in multiple ways, again going to thermal stats. In your examples you''re unstated assumption that your gas contains the same number of moles during use; which is not the case. Your "mole usage" will be at a different rate than that of the pressure in the system. Hence why (and you probably didn''t have any clue to this) this is called the "Ideal gas law" as it''s ideal to find out the real values of a hypothetical mechanical state of a gas. In the stated reference above, he actually ignores the fact that there are about 3 other formulas involved to actually derive to his final equation, all of which are very important.

If I have offended you, then I apologize; however I know I''m right so there''s no point in arguing over the internet.
I merely wanted to point out the boiling water tid-bit, and to inform you of the science about what is gong on.

What brought me in closer with some people on this forum, as well as the forum in general, is the attention to details and the accuracy of information portrayed is very important to us. We don''t like half-assed answers (unless we''re kidding around) and we certainly don''t like to guess.. i could be speaking for more people than I should, but this is how I -definitely- am.

Now, back on topic after all that....

If YOU would have read, I''ve never stated that it doesn''t work, or will not work...
In fact, I''m the one who first posted links to said video in this thread. I know it''s done, I''ve seen it done; I know it *can* work.

Also, you don''t state exactly which technique you attempted.
And also can you circle your dents in your pictures? I can''t make out what''s a dent and what''s a shadow of a curve or reflection... also since they aren''t directly associated with eachother I can''t tell which goes with which.

I''''m still in college and am not majoring or minoring in physics so I guess I have no room to argue.

The technique that I used was applying dry ice to a car that had been heated by the hot NC sun all day.
Here are the before pictures again with circles drawn so you can see the dents. Like I said; they are not very big.

Make sure you click them to see the circles





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Thanks for the pictures and for following up!
It is sort of hard to tell which is which and where the dents were located.
 
Hmmm...I am debating this or using dry ice.  I have a few door dings from stupid people so I am curous if it would work on those.

A little update; I didn''t take the time to check up on the dents. It seems they have popped back, when the car heated back up in the sun. No worse, just the same as they were before. I don''t think the car was hot enough before I did it. I could have also kept the ice on for longer.
I think this would work if someone wanted to take the time do it right. I just have a couple hundred dents and hate spending that much time.

I don''t think the pops a dent will work on dents that small . I''ve only used on one , but the smallest puller base in the kit I got was 1" . I looks to that the puller would have to be small enough to fit down in the dent for it to pull it out . I could be wrong , like I said just used it once .
BTW , I don''t know if hot or cold water freezes faster , but I''ve found that if I put hot water in my ice trays the cubes come out without breaking and they break when filled with cold water . And that''s information I can use , lol . six