Water beads magnifying the sun/burning holes in the CC???

[imported_mirrorfinishman]

Think of it this way. When you get out of the shower you feel cold because the water droplets on your skin are absorbing the heat energy from your skin and breaking free of the liquid state and entering the gas. Its an endorthermic process. Same happens with your car, but nowhere near the extent of actually damaging anything.

Actually, the above statement is not correct.



The reason you feel cold when you get out of the shower is because the water droplets on your skin are actually begins to cool as the evaporation process gets underway. Likewise, the water droplets on the surface of a vehicle are also cooling as they evaporate.



Personally, I have to agree with JuneBug; how many old cars have you ever seen in a junk yard that look like swiss cheese?

 

[Super_Herb]

Actually, the above statement is not correct.



The reason you feel cold when you get out of the shower is because the water droplets on your skin are actually begins to cool as the evaporation process gets underway. Likewise, the water droplets on the surface of a vehicle are also cooling as they evaporate.



Personally, I have to agree with JuneBug; how many old cars have you ever seen in a junk yard that look like swiss cheese?

No, that statement is 100% correct. Evaporation is an endothermic reaction.....and the definition of an endothermic reaction is a reaction that absorbs energy in the form of heat from its surroundings.



The water molecules on the surface of a water droplet must absorb energy in order to gain enough kinetic energy to break from of the molecular forces of the liquid water droplet. To put it in a simple way, they do this by absorbing heat from the surface of whatever the water droplet rests on, giving them enough energy to break free and fly away on their merry way as a gas.

 

[imported_mirrorfinishman]

Hey, I am not making this stuff up. Notice the part about evaporative cooling. That could be the key to why cars that bead do not look like swiss cheese.



From Wikipedia, the free encyclopedia:



For molecules of a liquid to evaporate, the kinetic energy of those molecules must be sufficient to overcome liquid-phase intermolecular forces.[1] Therefore, evaporation proceeds more quickly at higher temperature. Evaporation also tends to procede faster with higher flow rates between the gaseous and liquid phase and in liquids with higher vapor pressure. Since only a small proportion of the molecules are located near the surface and are moving in the proper direction to escape at any given instant, the rate of evaporation is limited.



As the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid thus decreases. This phenomenon is also called evaporative cooling. This is why evaporating sweat cools the human body.



Evaporation - Wikipedia, the free encyclopedia

 

[Super_Herb]

Hey, I am not making this stuff up. Notice the part about evaporative cooling. That could be the key to why cars that bead do not look like swiss cheese.



From Wikipedia, the free encyclopedia:



For molecules of a liquid to evaporate, the kinetic energy of those molecules must be sufficient to overcome liquid-phase intermolecular forces.[1] Therefore, evaporation proceeds more quickly at higher temperature. Evaporation also tends to procede faster with higher flow rates between the gaseous and liquid phase and in liquids with higher vapor pressure. Since only a small proportion of the molecules are located near the surface and are moving in the proper direction to escape at any given instant, the rate of evaporation is limited.



As the faster-moving molecules escape, the remaining molecules have lower average kinetic energy, and the temperature of the liquid thus decreases. This phenomenon is also called evaporative cooling. This is why evaporating sweat cools the human body.



Evaporation - Wikipedia, the free encyclopedia

Not to take this post off course....but what the heck, I will. :nervous:



I think we're basically saying the same thing just on different scales. A body of water cools during evaporation from it's surface due to what you just said above.



But a water droplet won't ever really cool down in temp in any measurable amount before it's gone. It's certainly attempting to, but the sheer massive amount of heat energy available for it to absorb from the body it's sitting on will easily replace any heat energy it is able to dissapate due to evaporation.



In other words, a lake will cool itself due to evaporation even with you swimming in it but a small drop of water that sits your body won't ever be cooler than before it hit your body. The physics of the evaporation is the same in either case.



To relate this in into Autopia terms......park your car in the sun on a hot summer day 'till the paint is good and hot, then pull it into the shade (to remove solar energy from the equation). Spray water from your hose on the car. Feel the temp of the nice beads of water (since we're Autopians, we all have nice beads of water on our cars....right?). The temp is much cooler than surface of the car. Now come back in 5 minutes and feel the temp of the water beads. They'll be lukewarm. Even with the cooling effect of evaporation on the water droplets, the temperature of the beads of water has increased rather dramatically. They've absorbed heat from the car at a faster rate than evaporation can dissapate the heat (and also helped to cool the car in the process) .



Now, take your car and put it back in the sun and get it up to the same temp.......quickly drive it into the lake. After you get your car towed out, measure the temp of the lake....it's not any hotter (and might even be cooler due to the evaporation) than when you drove your car into the lake.



It's all in the thermodynamics.......of which I don't remember much of from school anymore.



Thus ends my horrible attempt at describing evaporation.....:think:

 

[Changeling]

Off hand I would say there is a better chance on an alien spitting some acid on the spoiler creating a bank shot onto the paint surface which in turn mixes with carnuba to change the molecular structure to a synthetic ultra alien polish that would eventually break down into a super fine alien cutting final polish that would give a completely new appearing finish with the next occurrence of water sheeting off the surface (on a shady day) south of Maryland ! People in Maryland never luck out ! Just my belief.

Changeling

 

[BigHonu]

Oh my.... Just so you know the micro pitting is a direct result of USSFMPT

US special forces micro pitting teams jabbing you hood with little tiny needles.



I've got it on film, I'd show you but then i would put you in danger.....

No problem....'Danger' is my middle name.

 

[jfelbab]

Here is what accounts for those pits in your paint.



What is Acid Rain? | Acid Rain | Clean Air Markets | US EPA

Effects of Acid Rain - Automotive Coatings | Acid Rain | Clean Air Markets | US EPA

 

[imported_mirrorfinishman]

Herb,



I think we can agree that at the very least, the water droplets on the surface of a vehicle are basically not increasing in temperture during the evaporation process. If they were heating up, that could lend itself to creating an even worse condition.



Thanks again for taking the time to post a more thorough explanation.



Best regards,

 

[chas.007]

bigger the bubbles,the better the paint is being protected

 

[jfelbab]

bigger the bubbles,the better the paint is being protected

You have some proof of that?



The size of the bead is not necessarily related to protection. Paint by itself will normally bead water if it is clean and absent any wax.



The size and height of the bead only indicates the degree of surface tension present. Some products are expressly formulated not to bead but to sheet water off the surface.



Some of the softest wax products I have ever used have the highest surface tension and do not necessarily offer superior protection. Remember Vista?

 

[06mustang]

I'd be more apt to believe that if you live in an industrial area with lots of acid rain that the beads could cause trouble for the paint. As the droplet begins to evaporate the H2O leaves and concentrates the acid solution until you just have acid left leaving a small pit etched into the paint. The sun can only accelerate the evaporation. Any pollutants in the air that are absorbed or otherwise picked up by the rain are going to damage your paint eventually. That pollution coupled with whatever settles on your car combine to make an evil mix.



I prefer sheeting action for this reason.

I am by no means an expert but what you say here makes sense

Looking at my car after it rains it's always filthy (easily noticeable on the windshield)

I would think sheeting action would carry away the airborne dirt

Got any recommendations for a good wax with these properties?

 

[jfelbab]

Most of Meguiar's products are designed to sheet rather than bead with the exception of M16 and Deep Crystal Carnuaba I believe. There may be a couple others but the products that sheet well are NXT and M21. Here is a time lapse series of a mini showing the sheeting action of M21. This series of shots is provided by OctaneGuy over in the Meg's forum.



m21beading

 

[06mustang]

Most of Meguiar's products are designed to sheet rather than bead with the exception of M16 and Deep Crystal Carnuaba I believe. There may be a couple others but the products that sheet well are NXT and M21. Here is a time lapse series of a mini showing the sheeting action of M21. This series of shots is provided by OctaneGuy over in the Meg's forum.



m21beading

Thats great info

Thank you

 

[White95Max]

I gotta chime back in here, that beading CAN be a problem, for the reason that truzoom mentioned (water spots on a dirty car) and in areas that get acid rain.

All rain is acid rain. Even rain over the most pristine areas will pick up some carbon dioxide from the air, creating carbonic acid raindrops. If you're in a particularly polluted area, you'll have various other chemicals in the air as well, creating nitric acid and sulfuric acid. Some acid rain can reach pH levels of 5.0 or less.

 

[imported_truzoom]

All rain is acid rain. Even rain over the most pristine areas will pick up some carbon dioxide from the air, creating carbonic acid raindrops. If you're in a particularly polluted area, you'll have various other chemicals in the air as well, creating nitric acid and sulfuric acid. Some acid rain can reach pH levels of 5.0 or less.

Where the heck have you been? :nana:

 

[White95Max]

Busy...too busy. All of my free time lately has been spent shoveling snow or snowshoeing.