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Beginners guide to machine polishing

FinerDetails

Official SCN Supporter
When machine polishing for the first time, many many questions will go through your mind. below I am going to try to put 8 years into words!!

Which polish?
Which machine pad?
What speed do I use?
How much pressure should I apply?
How often should I work the area for?
and so on.....

The aim of this Guide is provide enough information to help you get started. It is by no means a"I've read it on the internet so now I am competent" post!!

For me there are five variables to machine polishing, and these will be referred to throughout:
pad
polish
speed
pressure
passes and technique.


Pads:
Available in around five grades, from finessing, finishing, polising, light cut and medium cut. Colours of each grade vary from one manufacturer to another, so where one grade is orange, the same grade by another manufacturer may be red.

Polish:
Machine polishes are available in many many grades of abrasive. Any good detailer will tailor the grade of the polish to suite the job at hand. It is not a case of one polish suits all cars, all or one polish suits the same car everytime. Just because the polish worked on a Ford Focus last time does not necessarily mean the same polish will work on the next!

Speed:
Machine polishers have variable speeds. Usually numbered one to six. Dont expect to start on speed six and hit the gold straight off. Time and experience will teach you how to use the speeds.

Pressure:
Light pressure for spreading polish, medium-firm for working, and light for finishing/refining. Not all polishes and paints react well to pressure, so time, testing and experience.

Passes and technique:
Experience of paint and the polish you use will provide you with the knowledge to know how many passes and hits to do when machine polishing. How fast to pass the machine from one side of the section to another is also a huge part of this. If you pass too quick the polish may not break down and do its job. Pass to slow and you may dry out the polish, or even damage the paint.


testing
First rule to start you off and always remember is testing. Test all your variables and find which combination works best. How do you do that? Select an 18 inch square area with the flatest and more consistent light. If it helps, box this off with masking tape. Make a mental note of the paint condition in the area, and any particular scratches or defects.
Start with the softest foam pad on the machine. The lightest grade of polish. Apply and work this polish with light-medium pressure. Apply a small pea sized amount to the pad edge on two places. Apply to the panels area on lowest sped and spread an even amount over the section, trying to achieve equal coverage. Once spread, increase speed as required.
Once the polish starts to break down and go clear, use light-no pressure and complete a couple of passes to refine the area. Wipe away the excess and assess the quality of the correction.
Has the pad, polish, number os passes, pressure and speed been enough to correct the level of defect to the desired finish? If not then you need to increase one of the variables.

pad
polish
speed
pressure
passes and technique.

Which one of these depends on the car you are working on, the conditions, the machine you are using, and also what polishes you have to hand. The only variable which is not finite is the passes and technique. Except the amount of paint available for you to polish is finite - never forget this!!

Pads - quick to upgrade the pad to firmer - but once you reach the cutting pads this stops!

Polishes - as with pads, easy to upgrade to more abrasive if you have the stock!

Speed - Limited more for G220 or PC users, as most machine polishing requires the max speed 5.5-6 already! Rotary users have ffar more power at hand - level one on the rotary can be seen to achieve the same results as level 5.5-6 on the G220.

Pressure - none, light, medium, firm. Tailor to meet needs and requirements.

Passes and technique - One passs for me is a pass from one side of the section I am machining to the other side. For example from top of bonnet to bottom. A hit for me is the whole section passed over in lines runing in opposite directions and over lapping from application to removal, and make mean the section has had 3-5 passes per line.

So which one are you going to increase?
You need to judge the amount of defect correction you achieved and how much more you need/require. If the defect correction was very low then pad and polish are a same move up.

If defect correction is almost there and try one of either slightly more speed/pressure or passes to give that bit more correction. The only true way to gather this knowledge is practise! Time and experience.

Now go out ther and get paint correcting, just not on someone else's car!
 

olaf

Dodo Lover!!
Aug 19, 2006
1,081
29
Ipswich
I shall also be ordering one before the end of February :D

Booked a couple of days off to, weather permitting, give the car a really good going over.

Will have a few questions on what other bits of kit I will need but am going to
post that in the main Detailing section.
 

jonjay

50 Years of 911
Jun 27, 2005
5,843
1
Essex
Iain can you please make this a sticky? Also can you expand the "lesson" by talking about why polishes dont duit same cars etc...
 
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