Working Temperatures

[wifpd4]

Read a post that indicated when buffing one should avoid generating heat from friction exceeding 100 degrees F. I'm sure there are several variables affecting this generality. Which to me seems low, as many folks were starting with surface temperatures at or over 100 degrees this summer. Some folks perhaps year round.

Ive also been told if you can't hold your fingers on the surface, it's too hot. That's probably around 130 degrees.

Please discuss the various surfaces (metal, plastic, fiberglass) and other variables that affect the safe limits of the generated temperatures when buffing.

Thanks.

[Please Wash Me Detailing]

today when I applied 205 to a black Bently it steammed!!! and it came out just fine. when working on hot paint you just have to work in smaller sections.

[wifpd4]

I was thinking more of what are the safe temperatures to prevent damage to paint when buffing. Say for example, I've got a scratch on a clear coated, plastic, bumper/bumper facia and I'm working with a 4" foam pad on a DA running at speed 5.5. What's the highest temp I should allow the surface to reach? Or is this question too specific and the the answer will be a generality? Which is fine. An answer of, "generally speaking 130 degrees" is acceptable.

[Please Wash Me Detailing]

Well I'm guessing my Bentley was around 185 degrees and that worked.
Now I don't recommend buffing a car in the sun. This spot I did was the side that the sun was hitting.
I generally don't think about working temp just the reaction of the process I am doing and if it works.

[Michael Stoops]

David, normally heat generated from friction as part of the buffing cycle shouldn't exceed 130F, primarily because once you reach that temp it can escalate extremely quickly from there and become very dangerous. This is especially true when working on plastic/urethane substrates like bumper covers because they don't dissipate heat like a steel or aluminum substrate will and you can very easily get hot spots that can lead to problems.

This is very different from "ambient" surface temps where products can flash dry when applied to a hot surface. For a mobile detailer who doesn't always have access to shade, sometimes you have to fudge things and you learn how to adapt. But best case scenario, if you can manage it, is to always begin work on a surface that is in the shade and cool to the touch. If you're doing anything that you feel is an aggressive process - 4" pads on a DA at speed 6 with moderate to heavy pressure - you need to regularly check surface temps that are rising as you work on the paint. But that substrate can be critically important due to variances in heat dissipation causing changes in buffing performance under some conditions.

[wifpd4]

"Wash Me", luckily the few times I work outdoors I do have a canopy if needed. So I can stay out of the sun.

Michael, Thanks for providing a point of reference limit for friction generated heat. It's those accursed "golf bag" scratches on non-metal bumpers creating problems for me. I would assume that 130 is a limit on hook and loop interface on pads and backing plates too.

[BillE]

I don't know if this germain to your question...but awhile back I was working on a 'gel-coat job' witn a 4" LC Yellow and just didn't have my head into the game. I have know idea of the temps I achieved but, I toasted both the pad and the backing plate.

I always try to keep an eye on how warm things feel, but this time went a bit too long. Like Michael said, once the heat started to rise it seem to get HOT quickly.

So in a nut shell, I'd say the pad/plate will poop out first not the polished area.

Bill

[TOGWT]

Kinetic friction induced heat can cause a rapid temperature rise; (i.e. initial surface temp 80.oF, friction heat attained with the polisher stationary and a cutting foam pad at 1,100 RPM for approx. ten seconds the friction induced heat attained would be around ~104.oF)

You should try to maintain as cool a surface temperature as possible when polishing, use your hand to provide a general idea of how much heat is being transferred by kinetic (friction) energy; it will of course be at a higher temperature than ambient.

When a localized spot is significantly hotter that the surrounding area you have a potential problem, the paint temperature can be checked by utilizing an instant read-out infra-red ‘gun type’ digital thermometer. In accordance with the Society of Automotive Engineers (SAE) a localized (spot) temperature should be limited to 115.oF (range 105 – 145.OF) above these temperatures the paint resin binder system becomes damaged and may fail

Dependent upon paint specification, thickness, and etc) as it will cause the paint to soften and the resin binder system to eventually fail Be cognizant that with high ‘spot’ temperatures the foam pad will cause scratching that is forced deep into the clear coat.

Above 115.O F and you create what the coating industry calls "thermal stress" - those long, small cracks in the paint that looks like light scratches, but cannot be removed by buffing. This phenomenon won't show up at first, but in a year or so the cracks will be evident.

[wifpd4]

This phenomenon won't show up at first, but in a year or so the cracks will be evident.

Good to know, thanks.

[Michael Stoops]

I would assume that 130 is a limit on hook and loop interface on pads and backing plates too.

Not necessarily. When working with a rotary buffer the heat generated will be where the pad and paint interface. The hook & loop on the backing plate/pad interface rarely gets above "warm" to the touch since the two parts basically just hook up and go. You can get the paint hot enough to melt or burn while the hook & loop is experiencing virtually no temperature increase.

In the DA buffing process the opposite is true. Since the pad is moving in an orbiting pattern on the paint it's not touching any one spot of the the paint with the same constant contact that a rotary does. Yes, at the center of the pad on a DA there is constant contact with the paint, but that's nothing like the outer diameter of a pad on a rotary contacting the paint. On the hook & loop interface, however, things are very different, and actually quite violent. Since the pad is oscillating the tool is always trying to throw the pad off the backing plate, but it's hanging on for dear life. You can bet that if you've managed to get the paint quite warm with a DA, the hook & loop is downright hot. In fact, in early testing with our DA Microfiber Correction system, we did some impromptu experimenting along this line. At speed 6 with massive downward pressure for about 30 seconds or so (maybe a bit more, like I said, it was an impromptu test not a scientific study) we got the paint quite warm to the touch but measured the hook & loop at 231F. That sort of temperature, for prolonged periods, will do irreparable damage to the pad and backing plate, but the paint itself would be unharmed.

With the often very aggressive approach used with the DAMF System, this is part of the reason why it's a good idea to change pads a couple of times in the buffing process - if only to let them cool down a bit. But really, if you're getting things seriously hot at the hook & loop, you might want to reassess your procedures.