Is heat good or necessary for machine polishing?

[Todd@RUPES]

If we keep in mind that polishing is a matter of science then we can dissect it. Let look at how heat affects the polishing process. Heat is a byproduct of the friction that occurs between the pad, the abrasive, and the paint. Heat is actually the energy lost according the The Law of Consevation of Energy.

So let?s look at what effects heat has on the process.

What effect does an increase in temperature effect the breakdown of the abrasive, or the rate of its break down? Like most metals, aluminum oxide (common abrasive) will become more malleable with an increase in temperature. However it would have to reach temperatures that are likely high enough to damage the paint before any real difference in application are noticeable.

In fact this can be proven by heating the abrasives with a heat gun. Aluminum oxide has a melting temperature of 3761 degrees F! While it will distort prior to reaching this temperature, it will not with any temperature we are capable of inducing with foam or wools pads on a painted surface. Simply put, the heat we are capable of producing while we polish is going to have no noticeable impact on the abrasive.

What effects does an increase in temperature have on the paint? Modern, catalyzed clear coat paints are chemically cross linked. You cannot heat them up and cause them to reflow. Drastic increases in temperature will damage the affected area permantely. Also, as the temperature of the paint increases, the paint will expand or ?swell?.

This is unwanted because as the paint expands the sharp sides that form the sharp edge pull apart, which can round the edge. For example, place your hands together like you praying. Now, keeping your finger tips touching spread your wrists so your fingers intersect at 90 degrees. Your finger tips represent a sharp edge. To represent the paint swell, spread your hands apart. The gap between your fingers represents what is left of the sharp edge. The gap will be bridged by a rounded edge. This happens at the microscopic level, which can make defects literally disappear until the paint returns to its normal shape.

How does heat affect the pad? There is some evidence to suggest that polyester becomes softer with an increase in temperature. At first this seems like a step in the right direction, but this can easily be compensated with the huge variety polishing foams available on the market. Softer is not always better, so it could even be worded that if excessive heat is used, you might have to step up in aggressiveness to compensate. Of course the amount of change in the foam is going to be very dependent on the particular formula of that foam.

How does heat affect the lubricants in the polish? While I could see the argument that an increase in temperature increases the flow ability of the lubricant (which may or may not be a good thing de pending on the design of the polish) the increase in temperature will cause the lubricant to evaporate quicker. This could cause the polish to dry prematurely.

If we look at the areas we examined: The paint, the abrasive, the foam, and the lubricant, we have one case where the result is negligible and three where the result is negative. The abrasive will not break down faster or more evenly because of a temperature increase, nor will the paint reflow or become more workable. To me it is pretty evident that increase in temperature serves no functional benefit and several drawbacks.

[Todd@RUPES]

PS

Copyright ME 2009

[David Fermani]

How does heat affect the lubricants in the polish? While I could see the argument that an increase in temperature increases the flow ability of the lubricant (which may or may not be a good thing de pending on the design of the polish) the increase in temperature will cause the lubricant to evaporate quicker. This could cause the polish to dry prematurely.

If we look at the areas we examined: The paint, the abrasive, the foam, and the lubricant, we have one case where the result is negligible and three where the result is negative. The abrasive will not break down faster or more evenly because of a temperature increase, nor will the paint reflow or become more workable. To me it is pretty evident that increase in temperature serves no functional benefit and several drawbacks.

Good info. I agree. I`ve attempted to polish many cars outside directly in the hot Florida sun and it very really seems to have the same effect as in a shaded area. It`s actually kinda scary when you`re doing heavy defect removal not know how far to push the limit. Excessive heat is not our friend.

PS

Copyright ME 2009

Haha - Let`s see if people change 1 word and call it their own material? Swiss Cheese Regurgitation. :cursing:

[LUSTR Detail]

Interesting indeed. I`ve always thought that it did help a bit, simply because warmer surfaces (ones that got warm during polishing due to the process, as opposed to those that aren`t worked long `enough`) always seemed to correct better than cooler surfaces, using the same pad/polish/paint... Then again, coincidentally, this could easily mean that polish simply isn`t breaking down correctly, thus not correcting to its highest potential, while the paint is still cool...

[Todd@RUPES]

Interesting indeed. I`ve always thought that it did help a bit, simply because warmer surfaces (ones that got warm during polishing due to the process, as opposed to those that aren`t worked long `enough`) always seemed to correct better than cooler surfaces, using the same pad/polish/paint... Then again, coincidentally, this could easily mean that polish simply isn`t breaking down correctly, thus not correcting to its highest potential, while the paint is still cool...

Since heat is a heat is a by product of friction, it could be that the increased friction is why you have gotten more correction, which makes sense. There is no doubt that friciton is the force most resposible for the total correction. The debate is whether heat, or an increase in tempature itself, does anything in and over itself. To the best of my research and experience, it doesn`t.

[LUSTR Detail]

Since heat is a heat is a by product of friction, it could be that the increased friction is why you have gotten more correction, which makes sense. There is no doubt that friciton is the force most resposible for the total correction. The debate is whether heat, or an increase in tempature itself, does anything in and over itself. To the best of my research and experience, it doesn`t.

Yea makes sense... I figured it`s simple coincidence that while more friction and properly breaking down the polish correct better, they, at the same time, generate more heat.

[imported_Luster]

Since heat is a heat is a by product of friction, it could be that the increased friction is why you have gotten more correction, which makes sense. There is no doubt that friciton is the force most resposible for the total correction. The debate is whether heat, or an increase in tempature itself, does anything in and over itself. To the best of my research and experience, it doesn`t.

So, what you`re saying is ... heat is a by-product of friction. The friction is doing the work, the heat has nothing to do with the correction of the paint....

Right?

[Dsoto87]

The logic of this makes sense to me. So in essence, heat doesn`t exactly help to break down the abrasives. Heat is just a byproduct of the friction that`s doing all the work.

If this is true, than that would kind of eliminate one of the rotary users arguments against using a DA. Whenever I see DA vs Rotary arguments, one of the main points is a DA will not produce enough heat to burnish/jewel the paint. So if heat has nothing to do with it and its purely the abrasives than a DA could technically burnish the paint. Granted it will take a bit longer to fully break down the abrasives, but it will get broken down in time.

Maybe I`m just rambling and I took Todds point all wrong.

[TOGWT]

[If this is true, than that would kind of eliminate one of the rotary users arguments against using a DA. Whenever I see DA vs Rotary arguments, one of the main points is a DA will not produce enough heat to burnish/jewel the paint. So if heat has nothing to do with it and its purely the abrasives than a DA could technically burnish the paint. Granted it will take a bit longer to fully break down the abrasives, but it will get broken down in time.]

[...a DA will not produce enough heat to burnish/jewel the paint.]

Heat as a requirement is an often misunderstood aspect of polishing

Heat from Kinetic (or dynamic) Friction

[ : when contacting surfaces move relative to each other, the friction between the two surfaces converts kinetic energy into thermal energy, or heat]

Kinetic (or dynamic) friction induced heat is an often misunderstood concept of polishing / compounding; abrasives require friction to breakdown, not heat; heat is just a resultant of friction between two surfaces. Kinetic friction is required to ?level? paint, which is simply the removal of paint to the lowest point of the paint defect. A finishing pad will not provide as much friction as a cutting foam pad, although they will both produce friction induced heat, whereas a wool pad, due to their composition, creates less friction induced heat but more kinetic friction than most foam pads.

Polishing a paint surfaces transfer?s kinetic friction induced heat to the paint surface, thermoplastic polymers have both tensile strength and elongation (elasticity) which allow the surface to flex, expand and contract in accordance to surrounding temperatures, solvents, resins and other ingredients in polishes will expand causing the paint film surface to expand.

As the metal substrate expands the paint moves with it, due to its elasticity, thereby becoming elongated (thinner) this is part of the cause of friction induced ?burn?, you?re applying pressure and an abrasive to a less dense (?thinner?) paint surface. Plastic has a much lower rate of thermal conductivity than metal, so it absorbs heats at a far greater rate.

Kinetic Friction induced heat can cause a rapid temperature rise; (i.e. initial surface temp 80.oF, friction heat attained with a stationary cutting foam pad at 1,100 RPM for approx. ten seconds would be approx. 104.oF) the paint temperature can be checked by utilizing an instant read-out infra-red ?gun type? digital thermometer, paint surface ?spot? temperature should be limited to 110.oF <

In accordance with the Society of Automotive Engineers (SAE) a localized (spot) temperature of 115.oF will cause the urethane clear coat to soften and the foam pad will cause scratching that is forced deep into the clear coat.

An extract from one of a series of in-depth, unbiased detailing articles ? TOGWT ? Ltd Copyright 2002-2008, all rights reserved.