Polish vs Compound vs Wetsand: Which to Use When


When you’re first looking into paint correction, it can seem a very confusing topic. There are loads of different machines, tools and products available, that it can be hard to decide what’s the best for you. Three of the biggest terms are polishing, compounding and wet sanding.

In this article, I’ll explain exactly what these paint correction techniques do, when to use which and what equipment you need. So let’s get started.

The Quick Answer

Wet sanding is the most aggressive form of paint correction and removes severe clear coat damage. Compound is used remove moderate clear coat damage, and hazing left behind by wet sanding. Polishing removes very minor surface defects to refine the finish after compounding to give a mirror finish.

Paint Correction 101

Before we jump into each specific technique, let’s go through a quick summary of paint correction. Essentially, all these techniques aim to create a flatter clear coat.

Most clear coats have scratches and swirls marks, which often come from bad wash technique, for example using a sponge or using a bath towel to dry the vehicle.

These clear coat scratches can only be seen properly in direct sunlight. However, they generally make the paint look duller and flatter in any type of lighting.

Paint correction techniques work by removing a layer of the damaged clear coat, to reveal a flat surface. This allows light to reflect evenly, making the paint look far more glossy.

There are three main techniques used to level the clear coat: wet sanding, compounding and polishing.

Wet sanding is the most aggressive, followed by compounding and finally polishing. So let’s take a look at what each technique does, and how it works.

Wet Sanding

Wet sanding is used to remove severe clear coat scratches. It is the most effective of the three techniques at flattening the clear coat, but it’s also the riskiest.

Wet sanding is an aggressive process which cuts away the clear coat quickly. You can attached a sanding pad to a machine polisher and use a lubricating liquid to sand away the clear coat.

So what are the dangers?

Well, the clear coat on your car is far thinner than most think. It’s actually thinner than a dollar bill. So using a process so agressive, runs the risk of removing the clear coat entirely.

This means you’ll be left with a matte finish, and no UV protection left.

Wet sanding should only be performed by experienced detailers. Yes, it’s faster at removing scratches than compounding and polishing, but the risks of ruining the finish entirely are very real.

Wet sanding should always be followed by compounding and polishing because it leaves a hazy surface. The sand paper itself causes scratches, so these need to be removed using a less aggressive technique.

Before wet sanding
Hazing left after wet sanding

Compounding

Compounding is the next most agressive solution to clear coat scratches.

You can use a “compound liquid” on a dual action polisher or a rotary polisher to remove fairly severe clear coat damage quickly. Take a look at this article I’ve written on DA polishers vs Rotary Polishers to learn more about this topic.

You can apply a compound liquid to a microfiber or foam pad, to flatten the clear coat surface. Some compound liquids are more aggressive than others. So some compounds remove scratches faster.

The abrasion level of the compound also affects the clarity of the finish it leaves behind. More abrasive compounds can leave light hazing, not as much as wet sanding, but enough to need another step of refining.

Other compounds are less aggressive and can leave an almost mirror like finish.

So it’s important to understand that there is a bit of a spectrum. So compounds will need to be followed by a polish, whereas others may not require it.

Before compounding
Minor clear coat imperfections after compounding

Polishing

Polishing is the least aggressive method of paint correction. There are two main reasons why you may use this technique.

  1. To refine the finish after compounding
  2. To remove very light swirl marks

Polishing cuts the paint away very slowly, so it can be used to get the flattest finish possible. That’s because it won’t leave any hazing behind like compounding and wet sanding. Instead, the clear coat will be completely flat, giving the car a mirror-like finish.

Polishing won’t remove deeper clear coat scratches and swirls, only very minor surface defects. Think of polishing as a way to refine, rather than remove clear coat imperfections.

You should always use a dual-action polisher, and a soft pad (either foam or microfiber), when polishing. The key is to be patient and gentle. You’re just trying to enhance the gloss, not remove scratches at this point.

Minor clear coat imperfections before polishing
Flat clear coat after polishing

Summing Up

Okay, so which technique should you use? Here’s my opinion.

  • Wet sanding should only ever be used to remove severe clear coat scratches and should only be performed by a professional due to the risks of burning through the paint.
  • Compounding is the go-to option for non-professionals to remove scratches and swirls. It’s a safer, but still effective option compared to wet sanding.
  • Polishing should be used to refine the finish and get the final boost of gloss. You should polish a car to refine the finish, not remove deeper clear coat scratches.

So if you’re looking to remove clear coat scratches to get that glossy, wet-look finish, start with a polish. If this doesn’t remove the damage, jump up to a compound. If you’re still struggling, then go to a pro who can try wet sanding.

You also need to remember that whenever you use a more aggressive technique of paint correction, it should be followed by a refinement stage.

So if you use an aggressive compound, follow it with a polish. And if you wet sand, then follow it with a compound, then a polish. This removes the hazing left behind from the previous method.

Take a look at these diagrams to demonstrate the process behind detailing a section of clear coat with severe damage.

  1. The clear coat has severe scratches which need to be removed by wet sanding. This is aggressive, but will effectively remove the damage.

2. Wet sanding removed the major clear coat scratches. However, it has left behind lots of smaller scratches due to its abrasive nature which need to be removed using a compound.

3. The compound step removed the hazing the wet sanding produced, but since it’s also quite abrasive, it hasn’t left behind a completely smooth and flat surface. This means a polish is required.

4. The polish removed all the hazing left by the compounding. This creates a completely flat clear coat giving the paint a glossy wet-look.

Thanks for reading! I hope you’ve found this article helpful. Don’t forget to check out the rest of the website to learn more about paint correction and detailing.

Heather

I first became interested in car detailing around 3 years ago and learnt all the main techniques on my very first car. I spend a lot of time detailing my current car, and trying to keep my family's cars looking presentable too!

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