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The Ultimate Guide to Foam Cannons: What You Need To Know - Redline Finish

The Ultimate Guide to Pressure Washer Foam Cannons: What You Need To Know

We have all seen those photos of that amazing car dripping with rich, thick foam. When it comes to washing our cars, that thick foam is the crown jewel the detailing fanatic searches for. There is just something special about it! How do pressure washer foam cannons work to generate those amazing suds? Is it just the foam cannon soap? Here we break down how a foam cannon works, its components, how it generates thick rich foam, the benefits, and proper maintenance.

Understanding The Pressure Washer Foam Cannon

There are a handful of components that make up a foam cannon. There is the canister, body assembly, pressure washer fitting, orifice, filter, nozzle assembly, and soap control knob.

Canister - The canister holds the foam cannon soap solution which the foam cannon pulls from. Typically 2 to 4 ounces of soap is used and the rest water depending upon the concentration of the foam cannon soap.

Body Assembly - The body assembly is what everything attaches to: the pressure washer fitting, orifice, soap control knob, nozzle assembly, and suction hose. The body assembly is the heart of the best foam cannon.

Understanding The Foam Cannon

Pressure Washing Fitting - The pressure washer fitting attaches to the back of the foam cannon body assembly. There are a few different types of pressure washer fittings. The one shown in the picture below is called a quick connector and is the most common. The material type you want to use is brass or stainless steel. Which one is better? Technically, stainless steel.

Pressure Washer Foam Cannon Fitting

Foam Cannon Orifice - The foam cannon orifice, although a small component in the foam cannon, is a big player in getting that thick rich foam you are after. The role of the foam cannon orifice in simple terms is to control the amount of water/flow that comes through the foam cannon. They come in a variety of sizes and the size you need is a component of the flow rate (gallons per minute - gpm) and pressure  (pounds per square inch - psi) of your pressure washer. The typical sizes used in a foam cannon are 1.1mm and 1.25mm. They go in the back side of the foam cannon body assembly (if you remove the foam cannon pressure washer fitting you will see it). If you are using a pressure washer operating between 1.3 - 1.8 gpm and under 2000 psi a 1.1mm orifice is likely a good starting point.

Foam Cannon Orifice - 1.1 - 1.25

Pro Tip: Use brass or stainless steel foam cannon orifices only. Believe it or not some foam cannons come with a plastic orifice and we strongly recommend staying away from those.

Filter - One very important component and easily overlooked is the foam cannon filter. Sure it helps filter out debris but its key role is to act as an agitator when the foam cannon soap solution and stream of water hit it to help generate thick foam. Depending upon your foam cannon some agitators are very cheap and poorly made and as a result, do not do a good job agitating. This can have an effect on generating thick foam from your foam cannon. The best foam cannons use a stainless steel filter.


Pro Tip: A sure sign the filter is clogged is you are not getting the output and amount of foam from your foam cannon as you once did.

Nozzle Assembly - The foam cannon nozzle assembly controls the spray pattern, turn it clockwise and you get a wider fan, while turning it counter clockwise you will get a narrower fan. If you open it too far it will just shoot out in a stream. Some foam cannons you can adjust the spray pattern to spray horizontally or vertically.

Valve knob - The valve knob located at the top of the body assembly controls how much foam cannon soap solution is pulled up through the suction tube. The use of this knob is debatable and is typically always closed to maximize the amount of soap solution that is pulled through your foam cannon to maximize the amount of foaming.

Foam Cannon Body Assembly

Is It Just The Foam Cannon Soap?

So how do you get that thick rich foam to come out of your foam cannon? Is it just finding the right foam cannon soap? Truth is, its a variety of components that when you get them all right you get what you are after...thick foam! The concentration of the foam soap is a component, also how much soap you use, the orifice size, the pressure washer operating pressure (psi) and flow (gpm), and the filter/agitator. Every foam cannon operates a little differently and it can take some tinkering to find the sweet spot. As mentioned previously, if you have a lower flow (1.3-1.8 gpm) and low/medium pressure (under 2000 psi +/-) from your pressure washer, you will likely want to start with a 1.1mm orifice. You will also very likely need to add more soap (4oz +/-) to your foam cannon to get thick suds. The spec sheet or directions on your foam cannon should tell you the minimum flow and pressure the foam cannon needs to operate properly.

Pro Tips:

  • Pour warm water into the canister, and then add the foam cannon soap, this helps generate thick suds!
  • Spray the foam on your vehicle and let it sit for a few minutes and then rinse it off to remove some of the dirt and debris off of the paint. Foam the vehicle down again and using the two bucket wash method to finish washing your vehicle. This multi step process helps reduces the chances of scratching and marring you're the paint. 

Benefits Of Using A Pressure Washer Foam Cannon

Now that we understand what a pressure washer foam cannon is, how it works, and the components that help generate thick suds, what are the benefits of using one?

  • Spraying the foam cannon soap on the paint surface provides a great lubricated surface to run your wash mitt over, which reduces your chances of scratching and marring your paints surface
  • The foam incapsulates the dirt particles on your paints finish to help safely remove the dirt and grime
  • Safely and effectively accelerates the car washing process
  • They are a ton of fun to use, there is just something special when you see those thick suds dripping off your ride!
The Ultimate Foam Cannon Guide - Redline Finish

Pressure Washer Foam Cannon Maintenance 

Your foam cannon performance is only as good as the maintenance you perform on it. Below are a few tips you can use to insure your foam cannon lasts a long time and performs its best.

  • After use always run clean water though it to clean it out
  • Check the filter periodically and  replace as needed
  • Foam cannons typically have seals that will need to be replaced over time
  • Check the foam cannon orifice from time to time and make sure it is free from debris
  • Use teflon tape to seal the pressure washer fitting on the body assembly.
  • Remove the canister from the body of the foam cannon to let it air out and completely dry
  • Use a pH neutral foam cannon soap

Wrap Up

As you can see there is a lot more to a pressure washer foam cannon than just a canister with soap and a nozzle. In order to get that thick rich foam we are all after, several factors come into play along with a good maintenance program. Also, not all foam cannons are created equal. The cheap ones you find, usually there is a reason why they are that cheap,  the parts material, quality, and machining tolerances are usually pretty poor. The best foam cannon typically consists of of stainless steel or  brass components.

Using this article as a guide should help you along the way to get the performance you are looking for out of your foam cannon and identifying the best foam cannon you will be happy with. We hope to have our foam cannon out in the near future.


Check out the Redline Finish store by clicking here. 

We hope your detailing experience is amazing! 






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