How Do Foam Cannons Work?

Foam cannons are one of those attachments that make pressure washers a worthy investment. Any car owner who has a gas or electric pressure washer owes it to themselves to get a nice foam cannon for their car. And if you don’t own a pressure washer, foam cannons are one of those pressure washer attachments that bump the washer’s value by a lot.

With all that said, let’s take a look at what foam cannons are and how they work.

What Is A Foam Cannon And How Does It Work?

Foam cannon parts

Foam cannons are both simple and effective devices. A foam cannon has three main components:

  • A water container, usually in a bottle shape, where you can mix warm/hot water and soap.
  • A spraying nozzle attached to the neck of the bottle with two or more spraying patterns.
  • A socket for a pressure washer wand on the other side of the bottle’s neck.

Even just from this brief description, it’s clear how a foam cannon works:

  1. The high-pressure water from the pressure washer’s wand goes through the neck of the water container.
  2. The container releases a bit of soapy mixture (as much as you set it to) into the high-pressure water stream.
  3. The soapy water is sprayed through the nozzle at high velocity, creating exceptionally thick foam suds that will easily deal with all the dirt on your car.

And that’s about it. The extra-thick foam created from the foam cannon + pressure washer combo will stick to your car’s exterior and slowly start dripping down, taking most of the dirt with it. The thicker the foam suds are, the longer it will take them to drip down which is a good thing – you want the foam to stay on your car for several minutes so it can really break down the dirt.

If the foam is dripping to the ground too quickly this can mean one of several things:

  • You need to add more soap to the mixture.
  • You need to increase the water pressure. (but don’t go over 1,500 PSI for cars and other vehicles or you may damage the car’s paint).
  • Either the foam cannon or the pressure washer isn’t of a high enough quality.

If everything is working properly, however, the foam should stay on your car for a while and help remove a lot of the dirt on it and soften the rest. Once you’ve allowed the foam to do its job, you can remove the foam cannon from the pressure washer’s wand and rinse it off. Then, you can finish washing your car with no fear of scratch marks.

The next question most people have here is “Why use a pressure washer at all? Can’t we just attach the foam cannon to a garden hose?” And that’s a good question which leads us to the difference between foam cannons and foam guns.

Foam Cannons vs. Foam Guns

Foam gun

Foam Gun at Work

It’s easy to confuse these two devices as they serve the same function. If you look at a foam gun and a foam cannon side by side they even look quite similar. There is one key difference, however:

Foam guns attach to garden hoses and foam cannons attach to pressure washers.

If you don’t have a pressure washer and you don’t feel like buying one, getting a foam cannon would be pointless. Instead, a foam gun has it’s own “gun” attachment which acts as a pressure washer’s wand. That “gun” is what attaches to the water and soap container on the other side of the nozzle and it’s also what the garden hose is attached to.

The result of all this is quite clear – foam cannons use much higher water pressure than foam guns because of the pressure washers they work with. And that is a pretty significant difference – the foam suds created from foam guns are much smaller, much more watery even when using extra soap, and they drop to the ground much more quickly.

This isn’t to say that a foam gun is necessarily a bad investment – they do work as advertised and they do create a fair bit of foam. So, here’s a quick breakdown of the pros and cons of both devices:

FOAM CANNONHigh-pressure washLots of thick foam suds that cover your car fully and take a long time to drip downRequires a pressure washer to work
FOAM GUNSmall and light devicesIndependent of pressure washers, can be used with just a garden hoseBecause of the lower pressure, the foam created by foam guns is thinner and less effective

In short, if you have a pressure washer or if you have enough other uses that can justify the purchase of a pressure washer – go with a foam cannon.

If you don’t have a pressure washer and you’re certain that you don’t want to buy one – get a foam gun, make sure it’s good, and use extra soap to create as much foam as possible.

Uses of Foam Cannons

Foam cannons are typically used to wash cars because of their convenience and versatility. The spray can get into even the hard to reach areas and effectively clean your car. Also, there’s something satisfying about standing with a foam cannon at full blast. Needless to say, it makes washing your car fun.

Foam cannons can also be put to other uses, like washing your deck, driveway, furniture, fence or fly screens. But of course, you can also do these with just the water pressure and without the foam cannon. It depends on the specific situation and whether the object in need of cleaning would benefit from soap and foam.

The Bottom Line

Foam cannons are quite simple in how they work, but the only downside is that you require a pressure washer to use them. If you already have a pressure washer, purchasing a foam cannon is a useful addition especially when washing your car.

To learn more about pressure washers and foam cannons, read our related articles:

Foam Cannon vs. Foam Gun – What’s the Difference?

How Do Pressure Washers Work?

Gas vs. Electric Pressure Washer

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