Bilt Hamber Auto Foam Review

Bilt Hamber Auto Foam is one of the most popular products on the detailing market and comes up constantly in detailing forums. Does it live up to the hype? In a word, yes. It is one of the most effective snow foams on the market for the removal of dirt and is also very cost-efficient compared to many others.

Testing showed a significant difference in cleanliness between a panel that was soaked in Auto Foam and one that was not before rinsing under low pressure. Snow foam is functional as well as aesthetic, at least this one is!

Prepmycar Rating: 8.3 / 10

Bilt Hamber Auto Foam (5 Litre)

Bilt Hamber Auto Foam (5 Litre)

9.5 Cleaning Power
Foam Levels
7.5 Ease of Use
9  Value for Money



  • Best in class for cleaning power
  • Easy to use on all paint types
  • Safe on waxes, sealants and coatings
  • Great value for money at ~50p per wash


  • Confusing dilution ratios
  • Can be strong if not diluted properly

Bilt Hamber Auto Foam – Testing Process

I tested Auto Foam by applying foam to one door panel of a car. After leaving it to dwell, I rinsed both the panel in question and the panel beside it, which had not been sprayed, with low-pressure water. The white paint shows the dirt very clearly, which made it easier to see a comparison.

Bilt Hamber recommends using Auto Foam at a 4% PIR (panel impact ratio). This requires a bit of work to calculate.

First, the foam lance must be filled with water only. Then the pressure washer is turned on and sprayed into a container until the foam lance is empty. You then measure the amount of water in the container and multiply this by 0.04. That number is the amount of Auto Foam to add to the lance before topping the lance up with water. The lance should be set to maximum concentration when calculating the PIR.

In my case, I am using a Kärcher K4 pressure washer with a generic brass foam cannon. When my lance was empty, 11 litres of water were collected. Multiplied by 0.04 gave me a value of 440 ml, which is roughly what I added to my lance and topped it up with water.

While this is the result I got, every lance and machine combination will produce different results, so it is well worth trying this to avoid wasting product or getting disappointing results.

It’s also worth noting that due to the viscosity of Auto Foam, it uses much less product than most snow foams. My 1L lance would have easily been enough for 3 cars, so bear this in mind.

Cleaning Power 

Auto Foam has been developed with serious scientific consideration. The product is designed to soak the surface while bubbles in the foam burst open and break down the soiling, allowing effective removal.

During the test, the side which was first soaked with Auto Foam came up much cleaner than the side that was only rinsed with water, highlighting the need for pre-washing. Not only was a substantial amount of road film lifted, but larger particles of debris were also dislodged by the foam.

It is important to remember that snow foams were never intended to become touchless wash solutions, rather, they are intended to form part of a maintenance wash, causing minimal degradation to the sealant in place. A caustic traffic film remover would be far more effective at removing dirt but would result in waxes being stripped.

Foam Levels 

Unlike many other products in the snow foam category, Auto Foam does not produce a whipped cream-like consistency. It is not particularly vicious and runs off the paintwork quite quickly, bringing with it much of the dirt.

The dwell time is still respectable, and on a cool day, snow foam with a PIR can easily sit for 5 minutes, allowing other tasks to be completed, such as rinsing wheel arches.

Here are some shots of it in use on my BMW M5 in Donnington Grey:

Ease of Use 

Snow foams are definitely one of the most enjoyable parts of detailing, there is something very satisfying about covering an entire car in a blanket of foam. Auto Foam is no more difficult to use in this sense than any other snow foam; however, users should be wary that the dwell time with this product is less than with many other products. Not so much a problem in winter, but in the summer months, dwell times will be a few minutes at most.

Users may find it irritating having to calculate the PIR for their specific lance/pressure washer setup, especially when other manufacturers tend to advise adding a certain amount to the lance without regard to flow rate. I do like that Bilt Hamber recommends this step, as the flow rate of the machine used will greatly vary the amount of product needed.

Auto Foam is green in colour and contains a pleasant pine smell. The foam produces dissipates quickly and is biodegradable. Other foams can dwell on the ground for hours after use, but this is not a problem with Auto Foam.

Value for Money

Auto Foam is, on a cost-per-litre basis, cheaper than many other snow foams. 5L can usually be bought for around £17.

When PIR is calculated, it may seem that more Auto Foam is needed than other products. In my case, 440ml of the product would cost almost £1.50, but this would be enough foam to cover almost three cars, so at roughly 50p per application, it offers good value for money.


As mentioned, Bilt Hamber recommends a PIR of 4% for normal use. It can also be used at higher and lower concentrations depending on needs.

A lower concentration can still yield good results, especially on coated vehicles. Reducing the concentration will have the added benefit of reducing cost per use. Increasing the PIR will remove more dirt but will also degrade sealants at a faster rate, as well as cost more.

For most applications, I think a 4% PIR is sufficient.

Auto Foam is an alkaline product which, contrary to popular opinion, is not a bad thing. The crucial factor is that it is non-caustic, so it will not dull the finish of the paintwork. Auto Foam will not strip waxes or sealants at a faster rate than any other snow foam.

Specialist Features

Auto Foam does not leave behind any wax or residue, meaning the next step of manually washing the car can be undertaken.

An excellent feature of Auto Foam is that it contains corrosion inhibitors. This will become apparent as the brake discs will not rust immediately, as is usually the case after washing a car. This factor also makes it a good choice for rinsing the chassis of a car.

About Bilt Hamber

Bilt Hamber, based in Essex, UK, are the industry leader in the research and development of automotive surface cleaners, treatments, and protectants. All of their products are developed in-house, and they have a range of other detailing products, including waxes, wheel cleaners and degreasers.

Bilt Hamber rebranded in 2020, and the 5L containers of Auto Foam have a new sleek look, with an extra-wide 63 mm opening for smoother pouring.


Does Bilt Hamber Auto Foam strip wax?

When used at the 4% recommended dilution rate, Bilt Hamber will not strip waxes or sealants. Bilt Hamber tested the durability of their own double speed wax against Auto Foam, and it took over 50 reapplications of foam before a noticeable degradation occurred. Using Auto Foam at higher concentrations will accelerate this.

Is Bilt Hamber Auto Foam environmentally safe?

Bilt Hamber Auto Foam is fully biodegradable and will not cause environmental damage.

Is Bilt Hamber Auto Foam pH neutral?

No, it is an alkaline product, however, it is a myth that only pH neutral chemicals are safe for cars. The crucial element is that Bilt Hamber Auto Foam is non-caustic, so it will not dull the surface of the paint, or strip wax at the correct concentration.

Bilt Hamber Auto Foam Review – Final Thoughts

Bilt Hamber Auto Foam is one of the most popular products in the industry, and with good reason. The product is a reliable performer and has become an essential part of many detailer’s pre-wash routines, both enthusiast and professional.

One of my favourite aspects of Auto Foam is the corrosion inhibitors, which are especially beneficial in the winter months. The scent is pleasant, but overall, I can rely on this product for effective cleaning. I would happily recommend it but make sure you take the time to calculate the PIR for your pressure washer set-up.

Bilt Hamber Auto Foam (5 Litre)
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