Machine polishing is an essential part of the car detailing process that happens after cleaning and decontaminating, but before protecting the paint. It’s designed to safely and efficiently remove a layer of clear coat paint to eliminate or minimise the appearance of scratches, boost gloss, and enhance the depth of colour.
In this guide, we’ll explain exactly what machine polishing is, the benefits, the process, and address some frequently asked questions about paint correction.
Paint Defects Explained
Before we address what machine polishing does and how it works, we need to first understand what paint defects are.
Modern automotive paint is split into different layers. The clear coat is the layer that sits on top (above the colour coat), resulting in a glossy appearance. Despite its protective role, the clear coat is quite soft and easily damaged.
Here are the most common clear coat defects and their causes:
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- Swirl marks: caused by poor wash technique e.g. using sponges/ brushes, and not pre-washing the paintwork.
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- Hedge rash: deeper clear coat scratches caused by impact from bushes and branches.
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- Holograms: typically caused by poor machine polishing techniques used at body shops after an area is repainted.
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- Sanding marks: these can be created at the factory or at a body shop.
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- Oxidisation: caused by UV exposure which results in fading.
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- Water spot and bird dropping etching: caused by corrosive chemicals which eat into the clear coat.
All these defects become very obvious under direct light for example on a sunny day, or under street lights. They cause the finish to look dull and inconsistent, reducing the depth of gloss and colour.
What Does Paint Correction Do?
Paint correction, or machine polishing, is designed to address the clear coat defects listed in the section above. It does this by removing the layer of damaged paint, revealing a fresh layer free from defects. In some cases, if the defects are too deep to entirely remove, the look of them will be minimised instead.
The process produces a much richer and glossier looking surface which reflects the light more evenly. This results in a truly stunning finish which is guaranteed to turn heads. It also rejuvenates older vehicles making them look brand-new again.
Preparation Before Machine Polishing
Before even thinking about picking up a machine polisher, it’s important to thoroughly prepare the paintwork first. If the paint is not deep cleaned and decontaminated, then the polishing process can actually add more scratches into the surface, as these contaminants are picked up and pushed around by the machine polisher.
Here’s how a car is prepared for polishing:
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- The paint is pre-washed using snow foam and hand-washed using a car shampoo and a plush microfibre wash mitt.
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- Iron and tar removal sprays are used to remove certain specific contaminants chemically.
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- A clay bar is used to remove any remaining bonded contaminants and leave the paintwork feeling completely smooth.
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- The vehicle is then dried and the defects inspected using bright artificial lights. A paint depth gauge is also used to assess how much the paint can be polished safely.
How to Machine Polish a Car
Once the deep cleaning and decontaminating has been undertaken, the car is ready to be machine polished. This process requires several pieces of specialist equipment.
What’s Needed
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- The machine polisher – several types are available such as dual-action, rotary and forced-rotation which all work differently to cut and refine the paintwork.
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- Polishing pads – made from foam, microfibre or wool.
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- Polish or compounding liquid – an abrasive liquid which is applied to the pad.
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- Microfibre towels – to remove the polish residue afterwards.
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- Inspection lights – to identify defects and their removal.
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- Panel wipe solution – a chemical which can be used to remove polishing oils after the process.
The Process
The machine polishing process should be performed in a controlled, indoor environment which is free from dust. Here are the basic steps involved:
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- The polishing pad is attached to the machine polisher’s backing plate.
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- Polishing liquid is used to prime the pad which is then spread across the surface at a low speed using the machine.
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- The machine polisher is then used to work the polish across a small area in overlapping circular motions at a higher speed. Most polishers typically rotate at around 1000 orbits per minute.
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- Once the polishing set has been completed, the polishing liquid can then be removed with a microfibre towel.
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- A panel wipe solution is then worked over the surface with a microfibre towel to remove any polishing oils remaining so the finish can be inspected.
Machine Polishing Variables
There are a multitude of variables which can be adjusted in order to control how much paint is cut away and how quickly.
Here are some of the variables which can be adjusted:
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- Machine type e.g. rotary or dual-action. Rotary machine polishers are best for heavy defect removal, whereas dual-action polishers are best for refining the paint and removing light defects.
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- Polishing pad e.g. foam, wool or microfibre. Foam pads tend to be less aggressive, but there are variations of all three in terms of aggression.
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- Polishing liquid. Again, there are different options available for different levels of abrasion.
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- Technique e.g. arm speed, polisher speed and pressure.
Cutting the paint more aggressively will result in faster defect removal, but can leave behind some light hazing, which will need to be removed using a second stage of polishing known as the finishing or refining stage.
Every car is different too, and some paints are harder than others. A more aggressive approach will cause more hazing on softer paints compared to harder paints, but a more abrasive combination will be required to cut the defects on hard paints.
Paint Correction vs Enhancement
When looking at getting your car professionally machine polished, you may have noticed that there are different packages available. Here are some of the most common and what they involve.
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- Paint enhancement: this is a very light machine polish designed to just improve gloss rather than remove clear coat scratches. It’s most suitable for lower budgets, or cars which already have good paint.
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- Single-stage polish: this is also known as a one-step polish. It cuts away around 50-60% of defects. Since only one polishing stage is performed, there needs to be a balance of having enough cut to remove plenty of defects, but not too much aggression that the clarity is sacrificed.
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- Two-stage polish: the first step will be used to cut away most of the defects, and the second step is designed to refine the finish and remove any hazing from the first step. This typically results in around 80-90% of defect removal.
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- Multi-stage polish: this also typically includes sanding and is designed to produce the best possible finish that can be safely achieved. It typically results in 95-100% of defect removal and incredible levels of gloss and clarity.
Risks of Machine Polishing
The process of machine polishing involves cutting a very thin layer of clear coat paint away in a controlled manner. When performed by a trained professional, this can be done safely without removing too much clear coat which would compromise the finish.
Using a paint depth gauge to assess the thickness of the paint prior to machine polishing is an important to step to avoid removing too much clear coat. It’s also important to be capable of handling and controlling the machine properly to avoid “burning through”.
This is why machine polishing is typically best left to professional detailers who have the proper training to ensure the best finish is achieved in a safe manner.
Hand vs Machine Polishing
Hand polishing is generally done by enthusiasts who are looking to improve the overall condition of the paint, without the risks associated with putting a machine polisher in inexperienced hands.
Polishing by hand doesn’t come close to machine polishing in terms of defect removal, but is a safe option for beginners. It also requires very little equipment to get started. A notable drawback though, is that hand polishing is a very tiring and time-consuming process.
A machine is much more effective and efficient, and will result in the best possible finish.
| Hand Polishing | Machine Polishing |
| Slow and labour intensive | More efficient process |
| Less risk of removing too much paint | More risk of removing too much paint |
| Suitable for improving overall gloss | Best at defect removal and overall finish improvement |
| Cheap and easily accessible | More expensive equipment and training is required |
What About After Polishing?
After a car has been machine polished, it will need to be protected in order to lock in the finish. There are a few different options including waxes, sealants and ceramic coatings.
Traditional waxes and sealants are cheap, easy to apply, and can be done after just hand polishing. Hence, they work well for beginners. However, if you’re looking for the best level of protection for your car, then choosing a ceramic coating is the way to go. A professional-grade coating applied by a trained installer can last for up to 10-years, far surpassing the 2-3 month longevity potential of most waxes and sealants.
It’s also important to note, that extra care should be taken when washing a paint corrected car. This includes pre-washing the paint before making contact, utilising a two-bucket wash method, and using high quality car shampoo and microfibre wash mitts. This will reduce the risk of wash-induced paint defects, and help to preserve the polished finish.
Frequently Asked Questions
How much does machine polishing cost?
In the UK, most machine polishing packages start at £350-£400. The price depends on the size of vehicle, the level of polishing required (e.g. enhancement vs two-stage), and the protection applied afterwards (e.g. wax vs ceramic coating).
Do new cars need machine polishing?
New cars need machine polishing in the vast majority of cases. This is because clear coat defects are typically inflicted either at the factory, or at the dealership when the vehicle is being cleaned and prepared for collection. Machine polishing addresses these clear coat imperfections and prepares the paintwork for protection e.g. ceramic coating.
Are car polishes and waxes the same thing?
Car polishes and waxes are not the same thing. Polishes are abrasive and used to remove clear coat defects and improve gloss, they also do not contain any protection. Waxes on the other hand are non-abrasive, and are only designed to help protect the paint and make it easier to clean.
How often should a car be machine polished?
It is not advisable to machine polish a car on a routine basis, as this risks unnecessarily removing the clear coat protection. Machine polishing should only be done to carefully remove defects or prepare the surface for a ceramic coating.
Can I polish a car at home?
Although it is possible to polish a car at home, it is best to stick to hand polishing as this is a cheaper and more accessible option, with far less risk of damaging the finish.
Book a Paint Correction Service near Leeds
We offer a range of car detailing packages including machine polishing and ceramic coating, and can advise on the best option to suit your budget and requirements. Based near Leeds, we cater for clients in the West Yorkshire and North Yorkshire areas including Ripon, Ilkley, Harrogate, Wetherby, Bradford, Skipton, Bingley, and Keighley. Get in touch today to find out more.