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View Full Version : Can you really burn car paint with a Dewalt 849 Polisher ?



frankosmusica
09-01-2011, 02:26 AM
I have a Dewalt 849 polisher I want to polish my own car, So I went and bought polishing compound medium scratch one and the three buffing pads. The cutting,poolishing, and finishing. Can paint really be burnt ? Ive heard many opinions many say if you stay on the same spot for a long time, some say not really if you have it in low RPM anywhere from 1000 to 1800. How good is a Porter Cable 7424 compared to the Dewalt 849 ? I heard the Porter Cable 7424 polisher is so safe that you can never burn paint with that one because of the way it spins ? This is what the guys from an auto detailing store told me how true is this ?

togwt
09-01-2011, 03:44 AM
Strike-through and Paint burn have a very similar cause and affect



Speed, kinetic energy (friction), applied pressure, foam pad actual surface contact area, pad and polish / compound abrasive ability, amount of surface lubrication available, area being polished, and material (paint, especially paint edges, plastic, metal, etc) heat conductivity



The above factors using a slow to stationary linier motion will produce excessive ‘friction heat ‘on a paint surface wither it be a rotary or an orbital polisher; the operative word here is excess friction. Basically strikethrough is caused when kinetic energy (friction heat) has compromised the clear coat and exposed the base coat. Paint often looks a slightly lighter colour; it’s usually concentrated on a small area or ‘spot ‘



You will also be able to see a non-glossy patch (base coat) where the clear has been removed with the edges of the remaining clear coat being visible. Since the clear coat contains the UV inhibitors, the colour coat is now exposed and will be subjected to photo degradation (fading)









FWIW- posting the same question in different sections probably won`t give you better answers

SVR
09-01-2011, 04:07 AM
from my experience, there are two types of paint burning



A: PAD BURN: pad scours the paint like you are using an angle grinder or wire brush at high speed.

B: DELAMINATION: Too much speed, pressure,friction, heat from rotary buffing that the paint gets too hot and the clear delaminates and bubbles up in certain spots.



I have done both - the second one done deliberately to see how far I can push it with a rotary.



Its surprising that often it is the orange CCS pads, megs burgundy pads and black finishing pads that cause pad burn the most. especially black pads that are extremely smooth/soft

imported_DetailDan
09-01-2011, 06:36 AM
Short answer- yes you can burn paint with the rotary @ that rpm AND with the PC if you try. Feel the paint as you`re polishing, you`ll see how hot it gets.

Accumulator
09-01-2011, 12:08 PM
[shoot], I`ve heat-damaged paint with a PC! And I wasn`t being stupid either.

lostdaytomorrow
09-02-2011, 08:34 AM
You can burn the paint with anything that contacts the paint if it is spinning fast enough and has enough pressure, these factors happen quicker with a rotary than a DA usually. A lot depends on the pad size and speed in this situation.

C. Charles Hahn
09-02-2011, 11:28 AM
What you need to do is go out and get your hands on a scrap panel, and start buffing. I`d suggest that you actually TRY to burn the paint. Once you`ve learned how to do that, file it under "how NOT to buff" and start working on proper technique to avoid causing damage.

extrabolts
09-02-2011, 09:07 PM
Definitely can. Just keep it moving along and you`ll be fine. Touch the paint after doing a section - it will surprise you how hot it can get.

Blackthornone
09-02-2011, 09:12 PM
Its surprising that often it is the orange CCS pads, megs burgundy pads and black finishing pads that cause pad burn the most. especially black pads that are extremely smooth/soft



A finer pad should have more surface area, and thus be able to build up heat faster.

careboy
09-03-2011, 04:51 AM
Short answer- yes you can burn paint with the rotary @ that rpm AND with the PC if you try.

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