[Rocks703]

Due to a few posts talking about scratches etc I thought I would post this as it helps understand what you are trying to do when removing swirls or a scratch (again I've borrowed it from another website)
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<b style="font-size: 13px; ">IN THEORY[/b]

Here we look at the theory behind machine polishing – what exactly is going on – to see how we can best hone practical technique to get the best out of your machine investment. The descriptions here apply to generic polishes that you will find on the market, though all do differ slightly in their characteristics.</font>


<i style="font-size: 13px; ">PAINT SYSTEMS[/i]
Shown in the picture below are the two typical paint systems you are likely to encounter when detailing: “single-stage” and “clear-coated”.</font>

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In all cases when machine polishing a car, you are working on the top layer of paint. You cannot remove more than this layer – indeed, you should always leave a healthy thickness of the top most layer. This puts a restriction on the defects which can be removed – any deep marks which go through the top layer of paint cannot be removed.</font>


<i style="font-size: 13px; ">PAINT DEFECTS[/i]
The paint defects that you may encounter are shown in pictures earlier on. We look at these in a little more detail here – for full descriptions please see separate guide.</font>
<ul style="font-size: 13px; "><li style="font: normal normal normal 10ptormal verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; ">Swirl Marks are light and shallow scratches covering large areas of the paintwork, typically inflicted by poor wash technique.<li style="font: normal normal normal 10ptormal verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; ">Random Deep Scratches (RDS) are deeper scratches into the paintwork, typically inflicted by grit being dragged along the paint, or minor key scratches.<li style="font: normal normal normal 10ptormal verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; ">Severe Scratches are marks which go through one or more of the paint layers, sometimes down to the bare metal – these cannot be sorted by machine polishing and require painting (minor filling or section respray) to fix.<li style="font: normal normal normal 10ptormal verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; ">Oxidisation happens generally to cars with no clear coat and causes the paint to fade and look dry[/list]
Shown in the picture below is a schematic of the typical paint defects.</font>

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<i style="font-size: 13px; ">REMOVING DEFECTS USING ABRASIVE POLISHES/COMPOUNDS[/i]
The most popular way of removing paint defects by machine is to use an abrasive polish. When worked into the paint, the abrasives cut away a layer of the paint where the defects are. Once the amount of paint removed is deeper than the defect, the defect will have been removed. It is like “re-flattening” the paint to a level where no defects exist.</font>

As mentioned above, when first approaching a car, always start with one of the lightest polish and pad combination that you have. This will remove only a small amount of paint, but may be enough if you have soft paint or only light swirls. Shown in the picture below are the above defects after being tackled with a typical light polish and pad combination (for example Menzerna PO85RD Final Finish on a Meguiars W8006 Polishing pad).</font>

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A thin layer of paint has been removed with the light cutting polish and soft foam pad. The combination has removed a lot of the lighter swirl marks, but has left the deeper swirl marks and the RDS and severe scratch. It is clear that there is still a healthy thickness left (can be checked with a paint thickness gauge in practice). So we would progress up the ladder to a more moderate cutting combination now to see if we can get better correction. For example, we may step up to Menzerna PO85RD3.02 Intensive Polish on a Meguiars W8006 Polishing pad to get the results shown in the picture below.</font>

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A thicker layer of paint has been removed and we have no fully corrected the swirl marks, both light and deep. The RDS remain however as it is much deeper into the clear coat. If the paint thickness permits we may wish to tackle the RDS with a heavier cutting combination to remove yet more paint. An example of this may be Menzerna POS34A Power Gloss on a Meguiars W7006 Cutting pad, to get the results shown in the picture below.</font>

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We can see that yet more paint has been removed by this process, however the RDS has been successfully removed. Great care must be taken when using compounds and removing large amounts of paint as leaving the clear coat too thin can cause it to flake off. Clearly the severe scratch cannot be removed as it goes through both the clear coat and colour coat layers.</font>

When working up through the abrasive scale to find the best possible combination for the paint it is worthwile bearing in mind that some of the marks that may be in the paint are too severe to remove safely. Always aim to leave as much clear coat (or colour coat on a two stage paint job) as possible. There are many reasons for this, just a couple are: if the uppermost layer is too thin, it can flake off and the only repair is a respray; if only a thin layer of clear coat is left then it will not be possible to machine polish the finish again with abrasives top remove any marks that may be inflicted at a later date.</font>

Perfection is a wonderful goal to aim for – but always bear in mind the safety of the combinations you are using for the finish you are using them on. This also applies if the paintwork seems soft – use of a compound on soft paintwork can remove large amounts of paint very quickly. So if you choose to use a compound on a car with soft paintwork, be sure to monitor the paint thickness regularly during the machine polishing process – after every few passes.</font>


<i style="font-size: 13px; ">REMOVING DEFECTS BY ROUNDING EDGES[/i]
This method is one which can be used with a moderate degree of success in situations where full removal of deeper marks is not possible for whatever reason (for example, paintwork is too thin). The machine polishing process can naturally round off the edge of marks on the paintwork as shown in the picture below.</font>

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The sharp edges of the deep mark catch the light and it is reflected back in an intense ray allowing you to clearly see the scratch in the finish. When the edge has been rounded off, there is no intense reflection of the light. It is instead spread over a wider area and it doesn’t appear as easily to the eye that there is a deep scratch there.</font>

This process is not fully removing the marks in the paintwork. Instead it is making them harder to see by essentially softening the edges, which acts to scatter the light rather than reflect it. This in turn makes it harder for the eye to see the marks. They are not fully hidden, but they appear a lot less severe.</font>


<i style="font-size: 13px; ">REMOVING DEFECTS BY FILLING[/i]
In some cases it is simply not possible to remove the swirls with an abrasive polish, for example if the upper most paint layer is too thin. Using a product with fillers gives another option in these situations – the defects are not removed, but instead they are masked by using fillers as shown in the picture below.</font>

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We can see that the original swirls above are quite deep compared to the thickness of the clear coat. Fully removing them by removing the paint would leave only a very thin layer of clear coat and this is something we would want to avoid doing. The alternative shown above is using fillers to mask the swirls. Not all swirls will be filled in perfectly, so complete correction using fillers will likely not be possible. However a significant improvement can be made without risking the paint.</font>

An issue with filling swirls is the solution is not permanent. Over time the fillers will be removed by washing and general wear and this will result in the swirls returning.</font>


<i style="font-size: 13px; ">THE POLISHING PROCESS[/i]
Here we look at how the polishes work the remove the paint defects as discussed above, with a description of the best generic techniques to work machines and polishes.</font>

Polishes which use a mechanical abrasive to remove the paint (most on the market including Meguiars, 3M, Menzerna, Poorboys, Optimum, Chemical Guys…) typically use a “powdered” abrasive carried in a solution with lubricant. The polish contains little abrasive particles which act under the action of the pad which moves them across the paint to slice off a little amount of the paint. It is quite similar to exfoliating the skin on your face with a facial scrub.</font>

In many polishes which are widely available, the abrasives break down under the action of cutting to become finer and finer. This means that as you polish, the amount of paint removed gets less and less. Shown in the picture below is a schematic of how this works in practice.</font>

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With the first passes of the machine across the paint, the abrasives are cutting a large amount of the paint away. As the polish is worked, the abrasives break down and the amount of paint removed gets smaller and the finish finer. Towards the later stages of the polishing set the abrasives have broken down to a point where they are removing only a very small amount of paint with each pass. The finish is now also much finer than at the beginning. The abrasives have diminished from heavy cutting through to fine finishing.</font>
It depends on the polish being used how aggressive the initial cut is and how fine the final refining is. Typically, a finishing polish (such as Meguiars #80, Poorboys SSR1) will have very light initial cut but a very fine finishing cut to deliver a sharp finish. An aggressive compound (such as Menzerna Power Gloss, 3M Fast Cut) will have strong initial cut but will not break down to a very fine finishing, thus resulting in a less sharp finish.</font>

Not all polishes break down in such a fashion however. Some polishes remain aggressively cutting throughout the set and for this reason they will require to be followed with a fine cutting finishing polish. Other polishes rely more on the cut of the pad to determine the level of cut and quality of finish, an example of which is MarkV Mystique. These latter polishes can be used on wool pads on rotary polishers to deliver significant correction. By dual action polisher they can deliver high levels of correction on a cutting foam pad, and lower levels of correction but fine finishing on a polishing foam pad.</font>

The use of different grades of foam pad will also affect the cut ad final finish delivered by a polish, the amount of which depends very much on the polish. For many light to medium polishes, the use of a polishing pad is generally sufficient and a more aggressive pad will not deliver that much extra.</font>

However for more moderate cutting polishes, the use of cutting foams can give a better cut and allow the abrasives to cut better. The flip side is that the more aggressive cutting foams can also leave marring of their own on a paint finish necessitating a follow up with a finishing polish to refine the paintwork.</font>

The levels to which pads and polishes cut and finish also depends greatly on the paintwork being tackled. Only by experimenting on a test section can you fully ascertain what each combo will do. For example, on some harder paints the use of a finishing polish on a finishing foam delivers very little if any discernable difference in quality of finish over the use of a medium cutting polish on a polishing foam pad. However on a softer paint which is more sensitive to the abrasives, it may be a completely different story, with big gains to be had by using a fine finishing combo to follow a more aggressive pair of products.</font>

 

[Rocks703]

IN PRACTICE

Having looked at what is going on with machine polishing in theory above, here we now look at how this works in practice.


REMOVING DEFECTS BY ABRASIVE POLISHES
As discussed above, the use of abrasive polishes eliminates defects by removing a layer of paint. The more aggressive a polish and pad combination used, the more paint that is removed. Thus more severe defects can be removed by using more aggressive combinations. However with all paints, regardless of any reputation about hardness of finish, always start with a light cutting combination and work up through the abrasive scale until you get the correction required.

EXAMPLE: HONDA S2000
Shown in the picture below are light swirls evident in a Honda S2000’s paint finish. The finish does not contain RDS or severe scratches.

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To remove the defects, a light polish and pad combination is tried first – for example Meguiars #80 Speed Glaze on a Sonus SFX-2 Polishing pad. This will remove only a small amount of paint. However as the picture below shows, this is adequate to remove the light swirls.

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Having found that this light polishing combination has delivered the required correction, the rest of the car can now be corrected in the same way. Regions of more severe marring, if they exist, can be tackled either by repeating an application of the light combination or stepping up to a more aggressive combination on the local area.

EXAMPLE: BMW E39 5-SERIES
Now let us look at something a little more severe. Shown in the picture below are moderate swirls and RDS in a BMW E39 5-series finish.

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Now BMW paint has the reputation for being hard. However, a light polishing combination would be trialled first just in case this was all that was needed – for example Menzerna PO106FF Final Finish on a Meguiars W8006 Polishing pad. The results of using this polish combination are shown in the picture below.

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Clearly in this case the light polish and pad combination has not had the desired effect. The swirls are still evident, as are the deeper marks. Only an improvement to the gloss is really evident and this is only slight. So, presented with this, we can see it is necessary to step up to using a more aggressive pad and polishing combo. Before doing this however it is prudent to check the thicknes of the paint to ensure that significant amounts have not been removed for little return – if this is the case, then chances are that to remove the marks will require too much paint removal and an alternative method would need to be looked into.

In this case we now move to trying out a more aggressive polish on the same pad: Menzerna PO85RD3.02 Intensive Polish on a Meguiars W8006 polshing pad. The results of this are shown in the picture below.

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The use of a more moderate pair of products has results in greater correction – the light swirls are now removed and the gloss more noticeably enhanced. But the severe swirls and RDS are still clearly evident suggesting that a more aggressive combo is still required. As before, the paint thickness should ideally be checked before stepping up the aggression scale to something more serious.

In this case, it is clear that the paintwork is quite hard and that the marring is severe which points to a compound being necessary. For example, Menzerna S34A Power Gloss on a Meguiars W7006 Cutting Pad. The use of an aggressive cutting pad and compound combination should be a last resort and the thickness of the paint should be checked before hand to ensure the safety of the method. Additionally the use of an aggressive compound can leave its own marks in the paintwork as discussed above. For this reason it should always be followed with a light polish and pad combination to refine the finish – for example Menzerna PO85RD Final Finish on a Meguiars W9006 finishing pad. Shown in the picture below are the results of using these combos on this paintwork.

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This combined aggressive combination followed by a finishing combination has resulted in all of the swirls and RDS being removed from the finish and a high gloss and clarity being restored.


REMOVING DEFECTS BY ROUNDING EDGES
As we have seen above, some marks are too deep to be fully removed. Either the mark is too deep or there is simply not enough paint. All is not lost however! Sharp edges on deeper marks catch the light and reflect it back in a beam which is easy to see with the naked eye. If these edges can be “rounded off” then they will scatter the light rather than directly reflecting it which will result in the mark looking less visible. This method does not remove the scratch, and it doesn’t make it invisible, but it does deliver a notable improvement.
 
EXAMPLE: JAGUAR S-TYPE
Shown in the photograph below is a deep scratch mark in the rear wing of a Jaguar S-Type. The area here has been polished already with a light abrasive to remove surrounding swirls and restore the gloss but the deeper mark is unaffected.

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Confronted with this situation, the paint thickness should first be checked to ensure continued polishing is safe. Here, complete removal of the mark would not be possible owing to its depth and the thickness of paint available. So in this case, a medium abrasive polish and pad combination (for example Meguiars #83 Dual Action Cleaner Polish on a Meguiars W8006 Polishing pad). The results of two applications of this process are shown in the picture below.

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The scratch is still visible, but its severity has been significantly reduced. The removal of sharp light catching edges of the mark have made it less visible.


REMOVING DEFECTS BY FILLING
Removing here should really be in quotation marks… This is quite often viewed as cheating as when using fillers, you are not removing the marks. Rather you are hiding them by filling them in, a bit like filling holes in a wall with plaster.
To call it cheating though is a bit unfair! There are many cases when the use of fillers to hide swirls is preferred to removing swirls with mechanical abrasives. For example, on a car where the paintwork is very thin, the removal of defects by removing paint is not possible so as to avoid the risk of striking through the paint. In this case, while not ideal from a purist’s perspective, filling the swirls will deliver a notable improvement that would otherwise have not been possible.

EXAMPLE: PEUGEOT 307
Shown in the picture below is the door of a Peugeot 307 with light to moderate swirls.

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If the paintwork on this door measured to be very thin (for example <80µm) then removal of these swirls with an abrasive polish would not be wise. Instead, a filler heavy glaze (for example Clearkote Red Moose Machine Glaze), applied using either a finishing pad or a polishing pad could be used. The fillers would be worked into the paintwork, to be worked into the swirl marks to help hide them. The results of filling is shown in the picture below.

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HOW EFFECTIVE IS FILLING?
Typically, removing swirls by filling is less successful than removing them with a mechanical abrasive. Shown in the picture below is a comparison between the effects of a moderate cutting polish, a finishing polish and a filler heavy glaze on the general swirls on a Peugeot 307 door (Filler on the left, abrasive on the right).

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THE POLISHING PROCESS
Having seen what various types of polishes can achieve in practice, we now look at the best ways to attain these results using a dual-action polisher.

HOLDING THE POLISHER
One of the most important things when machine polishing is to get comfortable! If you are tense or stretching awkwardly, you will find the machine polishing experience an uncomfortable one. Always ensure before you switch the machine on that you can easily reach all areas that you are planning to tackle, and that the pad is of suitable size.

You typically hold a machine polisher with two hands. However some users will prefer to use the tool one handed. Finding the best way to comfortably hold your machine will take time and there is no right or wrong way providing a few basics are observed: you want to be able to comfortably move the machine around the paintwork; ideally you want to be able to control the amount of downwards pressure over the polishing pad. Typically, you would hold the machine at the back with your writing hand and over the head with your other hand as shown in the picture below.

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Most dual action polishers come with a handle – either a side handle in the case of the PC7424, or a D-handle in the case of the Meguiars G220. The use of the handle is purely personal preference – try holding the machine with and without the handle to see which you prefer. Shown in the pictures below are examples of the Porter Cable 7424 being held using the handle, and without the handle.

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An important point when holding the machine polisher is to ensure to keep the cable over your shoulder as shown in the pictures above. This prevents the cable trailing along the paintwork inducing marks of its own.

Another important point is to relax! Dual action polishers vibrate, if you are holding on to a machine tensely then the vibrations will cause you pain quite quickly. Additionally if your driving arm (arm at the back of the machine) is tense, you will be less able to easily follow the contours of the paintwork. It is necessary when machine polishing to keep the pad flat at all times – this will be much easier if your driving arm is relaxed as you will find yourself better able to follow the contours and shapes of the body panels you are polishing.

DRIVING THE POLISHER
A dual action polisher will require to be driven across the paintwork when switched on – it has little to no inclination to move itself. This makes it an easier machine to control when first starting out in machine polishing. Driving of the polisher is generally down with the back arm (your writing arm), while the arm over the head of the polisher is simply controlling the downwards pressure onto the pad.

It doesn’t matter what pattern you move the machine polisher across the paint area in. Side to side, up and down, figures of eight, combination of all of them… So long as you cover the area evenly!

When using abrasive polishes, the machine should be moved at slow speed across the panel – approximately 1” – 2” per second. This allows the abrasives to be worked as discussed above to get the best cut and best finish. When using cleansers and glazes, the machine can be moved faster (using slower speeds) – around 3 – 5” per second.

Different products require a different amount of pressure when being worked. Many abrasive polishes work with between 10 – 15lbs of pressure. To get an idea of how this feels, push down the machine on a pair of scales. As a rough guide, when in use, you will hear the tone of the machine’s motor change slightly under this amount of pressure. To vary the amount of pressure, push down over the head of the machine using your arm. It is important to experiment using different pressures with the products you are using to see what delivers the best results on the paintwork that you are working on as while some products need pressure to get the best from them, others work best with only light pressure or none at all.

When using the polisher, ensure that the pad is not only vibrating but also turning in circles as well. This is best assessed by drawing a thick black line on your backing plate – you should see this line rotate at about 1 – 2 times per second. If the pad rotates faster than this it is not a problem, especially at high speeds. If the pad is not rotating then this means you are using too much pressure on the pad. Reduce the pressure until the pad begins to spin. Pay particular attention to this when working near edges and contours as these can be pressure points which will cause the pad to stop spinning. Additionally, pressure points can increase the risk of paint damage if too much pressure is used.

It is very important to start and stop the machine polisher when the pad is in contact with the paintwork. If the machine runs with the pad in mid air there is a large risk of the pad (and any product on the pad) flying off the machine at high speed!

WORKING AN ABRASIVE POLISH (DIMINSHING ABRASIVES)
As discussed above, the abrasives in many machine polishes on the market are diminishing abrasives. This means that they need to be worked through their stages of cutting from high to finishing. Here we look at how this would be done in practice. This is just a generic technique and guide to working such polishes – each polish will have its own characteristics and only through experimenting will you be able to find the best possible working methods that suit your technique.

Key to getting the best out of the abrasives in a polish, both in terms of cut and in terms of finish, is to work on a small area at a time – of around 12” – 18”square. Once the pad is initially primed with polish (a 3 – 4” line is enough for this), only a couple of skittle sized beads of polish are typically required.
With the machine switched off, spread your polish around the area you plan to work. You can either dab the pad on the paint, or drag it across the paint. The switch the machine on a slow speed (PC: 2-3; UDM: 2; G220: 2) and spread the polish with one or two fast passes across the area as shown in the picture below. You can see that the residue of the polish is white and cloudy looking.

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Once the polish is spread, step the machine up to a higher speed (PC: 5; UDM: 4-5; G220: 4-5). Now increase the amount of pressure over the head of the machine as appropriate, ensuring that the pad is still rotating.

Move the polisher across the area at a slow speed of about 1” – 2” per second. Make three or four passes at this speed to begin working the polish. With certain polishes, for example Meguiars #83 Dual Action Cleaner Polish, keep the machine at this speed for the duration of the polishing set until the abrasives have fully broken down. The picture below shows the polish beginning to be worked.

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For many other polishers, step the machine up to a high speed (PC: 6; UDM: 5.5; G220: 5.5), maintaining the pressure from above. Continue to ensure the pad is rotating. Don’t be tempted to speed up the movement of the machine (you’d be surprised how easy this is!) – keep it to 1” – 2” per second. Keep going until the polish residue goes clear as shown in the picture below. The residue will look like thick water has been spread across the paint and the white cloudiness will have vanished.

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When the polish is at this stage the abrasives have fully broken down as described above, allowing you to get the best from the available cut and also the best finish the abrasives have to offer. The finish will be free from micromarring as discussed above (unless an aggressive compound has been used on softer paint).

NB: The Cyclo machine polisher is only single speed. In this case, spread the polish around with a single pass moving the machine quickly and then slow the machine movement down to work the polish as described above until the residue goes clear.

So in summary:

1. <li style="font: normal normal normal 10ptormal verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; ">Spread or dab polish around the panel with the machine switched off.<li style="font: normal normal normal 10ptormal verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; ">Spread the polish with one or two passes at slow speed (between 2 and 3).<li style="font: normal normal normal 10ptormal verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; ">Begin to work the polish in for three or four passes at medium speed (around 4).<li style="font: normal normal normal 10ptormal verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; ">Thoroughly work the polish until the residue goes clear at high speed (between 5 and 6).<li style="font: normal normal normal 10ptormal verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; ">Buff off residue and assess result.

WORKING A FILLER HEAVY GLAZE
Unlike polishes which contain abrasives, filler heavy glazes such as Clearkote Red Moose Machine Glaze do not need to be thoroughly worked to “break them down”. Instead, they simply need to be worked long enough to work the fillers into the swirls.

As for an abrasive polish, the glaze should be dabbed around the area intending to be worked before the machine is switched on. This area can be a little bigger than for a polish with mechanical abrasives as we do not need to focus the effort down as much as before - 2’ square or a little more is acceptable. The glaze should be spread as before at a slow speed (PC: 2-3; UDM: 2; G220: 2).

Then the glaze should be worked into the paint with a few passes at a moderate speed (PC: 4-4.5; UDM: 3.5-4; G220: 3.5-4). Light to medium pressure is typically all that is needed for working a filling glaze. Work the glaze for a few passes (experiment to find out what works best).

 

[acrorat]

Gives Rocks the longest post of the year award

It's good stuff though, ever so handy to have easy access to this info.

 

[JukeAttitude]

Rock.. You The Man

 

[jµke]

Rocks... you rock, great information.

 

[NISSAN FAN]

what polishers do you use rocks , ive used a few over the years but my current work kit contains a 3m rotary and a das6 da , i have used makitas in the past but the weight of the 3m sold it for me

 

[Rocks703]

I just have the DAS6. Never took the leap to a rotary (mainly as the DA does what I need) Think I might get the new Meg 220 V2 as that is get some good reviews.
I like the Hex logic pads as they seem to last the longest.

 

[NISSAN FAN]

i have about 50 pads all different but the hexlogic and 3m are my favourites although meguiars ones are good too , i find certain pads work better with certain products so it depends on how bad the damage/swirling/hologramming is ineed to remove as to which pad ect i use

get a rotary rocks you'll never look back lol , keep the da for finishing but a rotary will do the job in half the time

 

[Rocks703]

The 3M does look a sexy piece of kit, I may go for it. I'll keep you posted

 

[NISSAN FAN]

if you do i think i4detailing are doing the best deal at the moment on them

 

[Siemarque]

Great post Rocks

I was was almost tempted to quote it, but didn't in case the forum burst!

 

[Turbo owner]

Very good read there Rocks
I've got the Das 6 good bit of kit
Wot pad and polish do u use