What is Presoak at Car Wash? Types & Advantages

Written by

Bruce Sonnier


Marcus Dutton

what is presoak at car wash

In car washing, presoak is something some car owners may not be aware of or may have encountered but don’t bother doing, but it can work wonders for the cleanliness and protection of a vehicle.

If you’re one of them, this article will help you understand what is presoak at car wash. Basically, it’s a step where contaminants are broken down and loosened for them to be removed more easily with soap, which also helps prevent scratches.

What is Presoak at Car Wash


The presoak is an important step in the process of an automatic in-bay car wash, tunnel, self-service car wash, and even in hand car washing at home. It’s one of the first steps done before car washes spray on car wash soap or manual soap application.

It helps break down and loosen the dirt, debris, and deeper stains on vehicles with the use of a special presoak solution.

Types of Presoak Chemicals


There are two types of presoak chemicals, which are based on their pH level, particularly the low pH presoaks and high pH presoaks. The pH determines their capability in tackling different types of contaminants. The differences between low ph vs high ph presoaks are explained below:

1. Low pH Presoaks

Low pH presoaks have low pH levels of around 1 to 6, which makes them acidic, and they’re sometimes referred to as acidic car wash soap. This type of presoak effectively removes contaminants that are inorganic, granular, and high in mineral composition.

2. High pH Presoaks

With pH levels of around 8 to 14, high pH presoaks, also sometimes referred to as high pH car wash soap, are alkaline and consist of alkaline builders and surface active agents or surfactants. This high pH cleaner works well in removing organic contaminants.

How Does Presoak Work?

In an automatic in-bay car wash or tunnel car wash spraying, the presoak occurs before the high-pressure foam application. Typically, it’s applied with several nozzles from an arch. In a self-service car wash, once this feature is selected in the car wash settings, the customer can manually apply it with the wand.

Advantages of Presoak in Car Cleaning

  • Targets specific contaminants.
  • Some presoak car wash solutions are designed to provide a middle ground as they work for various contaminants.
  • Makes cleaning easier for other chemicals.
  • Makes protectant application easier.
  • In the case of manual car washing, it helps reduce efforts in cleaning.
  • Helps prevent scratches and swirl marks.

When Should You Use Presoak


1. High pH Presoak

When your car is soiled with organic contaminants, it would be advisable to get a high pH presoak. Examples of organic contaminants are:

  • Bird droppings
  • Bugs
  • Soil
  • Road film
  • Oils
  • Grease
  • Other contaminants from nature

2. Low pH Presoak

When your car is covered with contaminants that are inorganic, granular, and high in minerals, it would be best to have a low pH presoak. Examples of such contaminants are:

  • Dirt
  • Sand
  • Clay
  • Salt
  • Lime deposits
  • Rust
  • Metal particles
  • Inorganic road film
  • Oxides

3. Use Them Together

For the best results, car washes often apply both high and low pH presoaks.

The use of both presoaks makes the cleaning more effective, and a neutralization reaction occurs as the second presoak is applied. There’s no exact order of presoak application, as the process all depends on some factors.

Some car wash operators or detailers found that it’s best to use the low pH presoak first to tackle the inorganic contaminants, followed by the high pH presoak to work on the organic contaminants and to neutralize the leftover acidity from the first presoak.

But some prefer to use the high pH presoak first and the low pH presoak second, as the low pH presoak can help make the vehicle dry easier, prevent water spots on the car, and make it shinier.

The contaminants can also vary in different places and times, so it would also depend on the environments where a vehicle runs.

Moreover, the distributor of the specific presoak would be the best source on the appropriate application method with their experience with their product and your local area’s contaminants.

Overall, experimentation and experience are required to be able to achieve the best results in presoak application.

Frequently Asked Questions


Is Pre Soak Safe for All Types of Vehicles?

Yes, it’s safe for all types of vehicles, whether cars, SUVs, trucks, or motorcycles. But it would be a good idea to also check the product label or consult the product’s customer service team to find out whether or not it’s safe to use on your vehicle.

Because some presoaks tend to strip wax and polymer coatings, you will need to reapply the protective coatings on your vehicle. To be safe, be sure to follow the product instructions on the application process. You can also patch test the product on an inconspicuous area before using it on the vehicle.

How to Use Presoak in Car Washing?

What to Prepare:

1, Pressure washer or a high-pressure hose

2, Presoak options:

  • Commercial presoak – high pH presoak or low pH presoak or both, depending on your car’s condition

– For application: chemical-resistant pump sprayer or foam cannon

  • Homemade pre soak – vinegar, dish soap, water, large container

– For application: spray bottle


1. Rinse off the loose contaminants on your car.

2. After rinsing, you’re ready for the presoak application. If you prefer to use a homemade car wash pre soak, combine in the large container the ingredients listed below. But if you’re going to use a commercial presoak, proceed to step 3.

    • Vinegar – a cup
    • Dishwashing soap – 2 tablespoons
    • Water – a gallon

Stir them well in order to mix them thoroughly. Then pour some of the solution into a spray bottle to be able to easily apply it.

3. Shake the spray bottle well before use. Evenly apply the presoak starting at the upper parts of the car, going down.

4. Let the presoak sit on the car exterior for a couple of minutes.

5. If you’re going for two commercial presoaks, both high pH presoak and low pH presoak, repeat steps 3 and 4 for the second presoak.

6. Again, starting at the upper parts of the car, going down, rinse the presoaks off thoroughly with the use of a pressure washer or high-pressure hose. Or you may simply proceed with a soap application.

How Often Should I Use Presoak at Car Wash?

Pre-soaking your car before doing significant cleaning is advisable, especially if your vehicle is incredibly soiled with stubborn dirt and contaminants.

How Does Presoak Differ From Other Car Wash Steps?

Although presoak is often skipped, it truly makes a difference in the car washing process.

It’s not an alternative to car soap or other maintenance products. But rather, it helps make the cleaning easier and prevent scratches by breaking down and loosening contaminants as it’s applied on the surface, prior to washing off the contaminants with soap and other tools in an automatic or manual car wash.


Now that you know what is presoak at car wash, make the wise decision of using it in your regular vehicle cleaning routine to make maintenance easier and prevent scratches on your car.

Presoaks are readily available for spraying in automatic and self-serve car washes for your convenience, but when applying them at home, make sure to follow the instructions on how to use them for safe and effective cleaning.

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