How to effectively machine polish with a dual action polisher

Polishing a car is the one step that can truly make the paintwork shine like new. When you clean your car you remove all the dirt from the surface, but you leave behind all the little scratches (also known as swirls) that are marked in the paint. These have generally appeared as a result of poor wash technique or general driving/parking issues (such as scrapes in car parks or vandalism).

A swirl mark or scratch is usually cut into the paintwork of the car and thus cannot be cleaned away. Instead, polish is needed to work on the paintwork itself:

These catch your eye as the sun reflects off the peculiar angles on the paint. Your eye expects the paintwork to be flat, however the reflections from the swirls reveal the true state of the surface.

How polish works

Polish comes in two forms:

  • Filler polish
  • Abrasive polish

Filler polishes infill the scratches making the scratches much less obvious. The swirls do remain on the paint however.

Abrasive polish rubs away the clear coat of the paintwork working to level the surface. This removes the scratch by bringing the surrounding clear coat down to the same level.

Either type of polish can be worked either by hand or with a machine polisher. Generally it is best to work from least to most abrasive polishes, stopping when you have achieved the desired level of correction. This prevents over correction e.g. wearing down the clear coat unnecessarily deep.

When working polish it is important to consider the thickness of paint, as too much abrasive polishing will remove the clear coat all together requiring a bodyshop to correct.

Filler polish

Usually filler polishes have little to no abrasives in them therefore there is no limit on the frequency of polishing with these. One of the most popular available is Auto Glym Super Resin Polish. It’s very easy to use so I would recommend it to a beginner.

To use this polish you will need the product, applicator pads for application and microfibre towels to buff off once cured. I usually apply and buff off by hand so this is a great introduction to polishing without breaking the bank:

  • Foam applicator pad
  • SRP
  • Microfibre towels

Apply a handful of dots of product to an applicator pad and place this surface on the paintwork (still working from the top down of course). Work your pad in small circles using a light pressure; you will be able to see the cream cloud over the surface of the car. Work over each panel evenly topping up the pad as it runs dry.

I cover the entire car in product before beginning to remove. Taking a microfibre towel, gently buff the surface to a brilliant shine using moderate pressure and circular movements.

The paintwork at this stage should look great, however deep swirls and any serious scratches will remain. If you are happy with the finish, move on to waxing to seal this brilliant shine in for good!

Abrasive polish

The following method can cause damage to your car so be careful. Too much abrasive polishing will break through clear coat into the paint layer (known as strike through), which will need a bodyshop to repair. That said, if you are careful it can be rewarding to properly correct paintwork on your car.

Working through this tutorial I will be using an entry-level dual action machine polisher (Kestrel DAS-6), Meguiars polishes (105 and 205) and Meguiars machine polishing pads (cutting, polishing and finishing pads).

  • Kestrel DAS-6
  • Meguiars 105
  • Meguiars 205
  • Cutting pad
  • Polishing pad
  • Finishing pad

Having a range of cutting power available allows you to work from least to most abrasive to find the correction level required. If you are looking to start out, try the least abrasive set up and add more abrasive pads and polishes in future. A good combination would be a Kestrel DAS-6, Meguiars 205 and a finishing pad. This combination would give a very light level of correction.

Most polishes have grains that are rubbed against the paintwork by the polisher, as these are worked they break down slowly until they are completely gone. Working the polish until these are gone is important, as not doing so could leave a number of smaller swirls which are inflicted by these grains (known as marring). If fully worked, as the grains break down they polish out their own marks until they are completely worked. 

Recently, some polishes are now non-diminishing which means the grains do not break down. Instead the effect of diminishing is replicated through the user altering the pressure and/or pad. 

How machine polishers work

There are two mainstream types of polisher for cars. A rotary has a fixed centre point and orbits in perfect circles only whereas a dual action polisher circles in random elliptical motions. 

With the more concentrated force, a rotary generates more heat and correction than a dual action in the same length of time, but is generally a higher risk tool as strike through is easier with a rotary. A dual action doesn’t repeatedly hit the same area of paint therefore heat and correction levels are lower and it is safer, however correction takes longer. Both have pros and cons, however I have used a DA for this guide.

Pads attached the polisher will have different cutting strengths as well as indicated on the packaging, the difference will usually involve density of foam (denser pads cut harder).

Controlling the polisher we will work in a taped off section of around 1.5 square feet in size. We will move back and fourth in straight lines applying pressure to the head of the polisher with our right hand.

Working a case study

Here we have a number of swirls on the rear quarter of a Focus RS. The paint on Ford is usually medium hard so we should be ok to use a DA without any major concern. The swirls are quite prominent:

We are using Meguiars 105 and 205 which are non-diminishing polishes. We therefore control the cut by varying the pressure applied to the head.

Apply 8 dots of polish (yes, that few!) to the polishing pad and spread using DA speed 1 over the area. The polish will cream up on the area. Now working at speed 3 we apply moderate to heavy pressure to the head of the polisher working slowly (around 2 feet/minute) from side to side, then move down and repeat. I work over the panel twice in this fashion. Before moving on, apply a light spray of quick detailer and buff off the remaining residue with a microfibre towel.

To finish working 105 which is non-abrasive, we will reduce the cut. Turning the DA speed up to 8 we will apply very light pressure to the polisher and work the panel at about the same speed. This less harsh cut removes most of the polishing marks from the heavier passes.

The 105 will have turned from creamy white to clear when it is worked appropriately. We do not want it to dry up when working. If this happens a quick squirt of quick detailer will dampen it up.

At this stage, you could complete the polish and wax the car up. However in order to get a really good mirror finish we will go the extra mile and use a very gentle finishing pad with a very gently 205 polish to repeat the above steps with two slow and two fast passes. This will buff up the finish with a very, very slight cut. Ultimately we are left with a fantastic mirror finish:

Once finished, ensure the surface is clear of residue by using quick detailer and a microfibre to wipe down. Move on to seal the finish under a wax to compete the look.

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