One question I commonly get asked by readers of this blog is “How many times can I polish my cars paint?” The truth is that there are too many variables in play to be able to give a cut and dry answer to this question.

Some of these variables include :

• What products are being used?
• What pad?
• What machine?
• What speed setting?
• How much pressure?
• Arm speed?
• How thick/thin is your particular paint?
• How hard/soft is your particular paint?

Those of you who are familiar with compounding and polishing will know that during this process you are removing a certain amount of clear coat to expose a fresh and defect-free layer of the paintwork.

The trouble with this is that there is only a certain amount of total thickness and depth of clearcoat, which means that potentially you could reach the limit if you polish the paint too much.

When talking about paint limitations and polishing, I am referring to machine polishing with a dual-action or rotary polisher (as opposed to by hand)

As many of you may already know, I am OCD about keeping my car swirl and scratch-free and have ended up performing multiple paint corrections on my cars throughout my ownership, and often have to remind myself to play it safe to avoid the risk of “overpolishing”.

Let’s take a look in more detail below.

How Thick Is Clearcoat?

As a general rule, most OEM factory clear coats have between 1.5 to 2.0 mils of clear coat on the body of the car. This can vary from car to car and some manufacturers can differ, but most fall within these parameters. Just to put that in perspective, that is thinner than a post-it sticky note. ( The average Post-it Note is around 3 mils thick.)

When Polishing/Compounding a car you are essentially removing a small amount of the clear coat to remove the imperfections. The amount of clear coat that is removed depends on some of the factors I have mentioned at the beginning of this post.

If you have polished a car before you may be familiar with the different levels of strength/abrasiveness available from these compounds. The most common being ( Listed in order of impact on clear coat)

1. finishing polish

2. fine polishing

3. medium polishing

4. heavy polishing

5. cutting compound

As a general rule of thumb, it is best practice when machine polishing a car to start with the least abrasive polish required to achieve the desired results.

For example, If you have some light swirling on your paintwork that could be easily tidied up with some medium polish, you shouldn’t just jump straight into using a heavy cutting compound. Will it remove the swirls? Yes, it will – but it will also end up removing a lot more of the clearcoat layer than necessary.

I have been guilty of this myself in the past, but the more I polish my car, the more careful I am with my choices.

When polishing a car, it is best to mix and match some polish and pad combinations to find the minimum effective dose required.

How Can You Tell How Thick Your Clear Coat Is?

One standard tool which is used by many detailers is a Paint thickness gauge. This measures the thickness of the car’s paintwork.

 

Unless you spend large amounts of money on a paint thickness gauge, you’ll only be getting a reading of the overall thickness of all layers – primer, base coat, clear coat – in one number.

This is fine if you’re working with factory paint since most factory paint uses something on the order 2 mils of clear coat, which should be the only thing you’re working on anyway.

If you take several readings on several body panels of a given vehicle you should have some pretty good consistency in those readings, assuming you’re dealing with a factory painted car.

This will give you a good indication of how much paint you have to work with during the polishing process.

How Much Paint Does Polishing Remove?

It is hard to give exact numbers, but here is a reasonably good estimate taken from Detailing Bliss :

Using a medium abrasive polish and a rotary polisher will remove approximately 0. 1 Mil (3µ ) Range 0.8 – 1.1 Mil (20 – 28 µ) from the paint surface (typically 4 passes at 1500-1800 RPM) but there are many variables such as the abrasive grade of the polish or compound and speed and pressure used that may affect the paint removed)

These numbers should be checked with a paint thickness gauge (PTG). There comes a point when you must judge whether removing a scratch will compromise the clear coat and if so you’ll have to ‘live’ with the imperfection.

A paint thickness reading of 4 Mil < ( 100 µ (Microns) is reasonably safe for polishing. 

If you have reservations about the amount of paint surface removed or the amount of paint coating remaining the use of a paint thickness gauge (PTG) is arbitrary

Note: 1 µ (micron) is 1/1000th of a millimetre or 0.0393700787 Mil or 0.001 of an inch

• 200µ + can be expected on older cars that have been hand-painted or a re-painted vehicle
• 100 – 200µ 4 – 8 mil – normal paint thickness
• 80 – 100 µ – 3 – 4 mils, thin paint
• 80 µ < – less than 3 mil, very thin paint

So- How Many Times Can You Polish a Car?

So you have all the numbers above, but what does that mean in plain English for the average detailer?

For most people with OEM factory clear coats in “normal” condition, it means that you can theoretically compound and polish your car safely multiple times without having to worry too much about clear coat failure.

As a rule of thumb for my own cars – I usually limit any kind of harsh polishing (Medium Cut or Above ) to two times per year maximum. This allows me to keep my paint looking fresh while also staying within the limits of the paintwork.

With lighter polishes such as a finishing polish, it is possible to use these on your car many times without worry, as the amount of clear coat they will remove is such a small amount it would be very very hard to polish through.

With older cars, I would recommend taking a safer approach and testing the paintwork first with a thickness gauge. If you don’t know the history of the paintwork and there is any kind of doubt, it is always best to test it first.

Once you experience clear coat failure there is no going back and you will have to get a respray on that area. Below is an example of clear coat failure courtesy of MeguairsOnline

Tips for Safe Polishing and Avoiding Clear Coat Damage

• Use a Dual Action Polisher instead of a Rotary if you are not an expert as these machines will generate far less heat and greatly reduce the chances of you burning through the paint.
• Always start with the ‘Minimum Effective Dose’ in terms of polishing pad and polish selection. Don’t automatically reach for something with strong corrective ability straight away.
• Implement safe wash techniques to reduce the risks of swirls and damage when washing and drying your car, which will, in turn, reduce the need for frequent polishing and correction.
• Always take extra care when polishing panel edges/lips where heat is inclined to build up more quickly.
• Check your work often to make sure your process is working.
• Use a paint thickness gauge if there is any uncertainty around the thickness of the paint.

Until Next time,

Happy Detailing!

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About the Author – Darren O Hara

Darren is the founder of the DriveDetailed blog and is a keen detailing enthusiast living in the rainy south of Ireland. When he is not cleaning his car he is always researching ways he can improve his techniques and enjoys testing out new products.

Darren currently drives an Audi TTRS and is a big fan of performance cars.

You can follow Darren on Instagram @darrenoharacork