Normally wash your vehicle with a bucket of soapy water? Most people do, including myself…but not always. If you keep your vehicle pretty clean, bucket washing is a perfectly safe way to remove surface dirt.

However, a foam cannon has its advantages, especially if you have a large vehicle. Foam cannons are pressure washer attachments that can generate thick foam on demand (instead of having to spray a bucket several times). Simply add soap to the foam cannon reservoir and spray it on. Foam cannons typically have flow regulators and a rinse water setting too.

To learn more about these devices, check out our beginner’s guide to foam guns and cannons and what we recommend for best results.

While both a foam gun and foam cannon can spray normal car soap on your vehicle, cannons are designed for pressure washers and use a special foam cannon soap—called snow foam— to pre-treat heavy dirt.

Now that you know the basics, here are 5 main reasons to use a foam cannon vs hand washing.

1. It’s easier to wash in sections…without missing a spot

With a foam cannon, you can coat an entire panel with a thick layer of suds or or foam…and see exactly where to use your wash mitt. I find it easier to work section-by-section when I can spray soap directly on a car’s surface instead of trying to generate enough suds to cover a large area.

If it’s hot, soap applied by hand may dry if you leave it on the paint while you finish adding soap to a section; if you spray soap on, you can begin removing it within seconds.

2. Your suds won’t get diluted

It’s very easy to run out of thick suds by the time you finish hand washing all panels. For larger vehicles, I’d rather use a foam cannon instead of having to add more soap, generate new suds, or clean my wash bucket out. I can wash a small car just fine by hand, but the bucket gets dirtier on larger vehicles.

Soap encapsulates dirt on contact, so the more you dip your mitt in a bucket, the more clean suds will ‘attack’ the dirt lodged in your wash mitt. The more you dip a dirty mitt in the water, the fewer suds in your bucket.

To remedy this problem, you can use a device called a grit guard inside your bucket to help keep dirt at the bottom (and away from clean suds). Check out our post on the 2-bucket method to learn more.

3. Reduced risk of scratching paint

Bottom line: if you have a bunch of visible dirt…it’s always a good idea to spray soap directly on the vehicle before you use a bucket to avoid leaving scratches or swirl marks. There really is no ‘best way’ to apply soap, because it all depends on how dirty your vehicle is.

For example, bucket washing a car you keep relatively clean is just as safe as using a foam cannon—if you work clean by rinsing the mitt out or using a grit guard. On the other hand, you wouldn’t want to hand-wash stuck-on clay or mud.

Foam cannons can create a high volume of suds or foam

In cases where your car is very dirty, foam cannons help prevent scratching because they can spray enough soapy water to cause dirt to slide off the vehicle. When it’s time to use a wash mitt for the remaining dirt, heavy dirt won’t be a problem

You want to only graze the surface to encourage the dirty suds to slide off the surface.

Some cannons and soaps produce more than others, and using a gas-powered pressure washer will typically produce thicker foam when used with a cannon (vs electric pressure washers).

If you’re in the market for a basic pressure washer to wash your vehicle, check out these 5 models under $300 I recommend. 

4. Foam cannons help avoid cross-contamination

Buckets can get pretty filthy in some cases—especially if you have road grime or traffic film on your entire vehicle. You’re better off spraying on your soap or foam in this case, instead of transferring oil, transmission fluid, and other contaminants from your wash mitt to your bucket.

As a rule of thumb, if you notice a gray or black film on your vehicle…it’s a good idea to remove as much of it as possible before using a mitt.

5. Speed

A foam fannon can speed up the wash process for larger vehicles compared to hand washing. That said, on small vehicles, you’ll often spend less time because you won’t need to connect a pressure washer wand, a garden hose extension, or toy with the spray pattern.

If you use a quality car wash you’ll see great results either way, it’s just a matter of personal preference.

Select the right wash method for your situation

Overall I highly recommend a foam cannon to car enthusiasts or anyone with a larger truck or SUV. That said, these devices may not be practical for you.

If you don’t have access to a pressure washer or running water, consider a rinseless soap solution like Optimum No Rinse. Check out our post on Washing a Car in An Apartment or Condo for more wash options.

At the end of the day, both professional detailers and hobbyists still hand washing and foam cannons…it all depends on the vehicle’s paint. Happy detailing!