Authored by: Nick Parks
The Pre-Wash Foaming Trend | Where It Began
It's an indisputable fact that YouTube has lifted the car care industry to a previously unrecognized zenith of enthusiasm, mostly healthy debate, and of course, profitability.
The accumulation of content pertaining to anything from proper washing to the most minute tactics for polishing likely spans thousands of hours, with nearly unlimited variation in methodology.
This is as much a collective benefit to our industry and enthusiasts as it is a dizzying trove of confusing (and occasionally confounding) information. While we have to acknowledge the fact that this virtual encyclopedia of detailing information is mostly composed of good information from good people, there are of course outliers. There are detailing professionals, detailing 'influencers,' (enthusiasts that share content often with the aim of earning a commission from companies that send them products), and amateur enthusiasts that happen to have a nice camera and some time to spare.
One topic that is often a source of tension between all three camps - if you could refer to it as such - is the idea that blanketing a car in a layer of soap & water with a pressurized cannon has any functional effect in safeguarding the clear coat of your car during the wash process.
Is there definitive data that sheds light on this topic? Not necessarily. It's largely subjective, but as professional detailing technicians, perhaps we can shed some light on our experiences to help you make a decision about how much time and money to allocate to this trend of sorts.
The Supposed Purpose of Foaming a Car
Many forum-dwellers, car care-oriented Facebook group members and YouTube personalities generally parrot two primary claims surrounding the process of foaming:
1. This layer of shampoo dwells on the car and runs off over a period of a few minutes, effectively dragging road grime & contaminants with it, or breaking down waxes.
2. This blanket of foam provides an extra dose of lubrication on the surface to help your wash mitt or wash pad glide over the surface, reducing the potential for 'love marks' or swirl marks.
At face value, those two statements aren't necessarily compatible - if most of the shampoo runs off of the car, then how is it possible that there's still enough foam on the surface to have an appreciable difference in washing?
We're getting granular here, but most of the debate on this type of thing is meant to be granular.
Dissecting Claim #1 | Foaming as a Method of 'Decontamination' or 'Touch-Free Cleaning'
First and foremost, there are hundreds of shampoo formulas available specifically for cars. Most of them claim to accomplish different tasks - to be usable in direct sunlight without consequence (pH neutral), to 'decontaminate' the surface (where decontamination isn't really defined as anything meaningful), or in the case of many cheap big box store soaps, to 'wash and wax' the surface.
Let's eliminate one of those ideas altogether. Car shampoos that contain silicones or waxes are detrimental to your efforts because they leave behind oils that prohibit protective products from bonding with your clear coat, and they often attract dust, sap, and other road grime. We highly recommend against using this type of shampoo whether in a foam cannon or in a bucket. These types of products are the results of a marketing tactic used to court the type of consumer who wants to spend as little time as possible caring for their car. If you've read this far, you aren't one of them.
Now, back on topic - there are essentially two types of legitimately useful shampoos, and we carry both in our store. However, insofar as cleaning ability goes, there are only a few variants of shampoos that could be useful in breaking down light layers of dirt and other various road grime.
Let's explore that in further detail.
The Chemistry of Useful [pH]oam
There's a fairly simple way of deciding which shampoo to use for a pre-wash solution; pH levels. Some manufacturers share this information, and some don't.
The pH Scale looks like this:
There are numerous examples of car shampoo formulations that fall towards either end of the scale, with a few truly straddling the middle (the middle representing the gentlest formulations).
Most automotive detergent or shampoo products range between pH5.5 and pH14.
In order to make educated purchasing decisions when it comes to car shampoo (and knowing which ones will be somewhat effective as 'foaming' shampoos), you'll need to decide what your ultimate goal is when foaming your car.
Are you trying to remove prior waxes or silicones, tree sap, bug remains, or other contaminants? Or are you simply wanting to leave an additional layer of lubrication underneath your mitt/pad as you complete your wash process? Some shampoos are better suited to the former, and some are better suited to the latter. Getting the most out of either type requires a slightly different mindset and approach to using them.
Here's a chart to make this decision process easy for you:
|Purpose||pH Target||Safe in Sunlight?|
Loosening road film, bugs, bird droppings, breaking down waxes
Lubrication only (gentle washing without removing waxes/sealants)
Breaking down sealants/inorganic compounds, attacking water spotting/mineral deposits
*pH-neutral shampoos (pH of approximately 7.0) are generally safe to use in sunlight, however, we do not recommend letting any product dwell on hot surfaces
Generally, alkaline/basic shampoo formulations (pH > 7.0) are more useful in attacking the most common organic contaminants that your car will encounter in daily usage.
For example, dead bugs & bird droppings are highly acidic (lower pH levels). Prolonged exposure to a basic/alkaline detergent type product raises their pH level, nudging them closer to the middle of the scale and effectively emulsifying them, allowing them to be rinsed and/or carried away by a wash mitt or pad. This is why bugs often feel "softer" after being exposed to a bug remover type product; the product is breaking down the remaining tissues.
Acidic shampoo formulas (low pH levels) are rarer in our industry, but have useful attributes when it comes to granular/inorganic compounds like salt, tar, and sand. Citrus-based cleaners are often acidic and contain citric acid (hence the name) and mixes of alcohol blends which tend to attack mineral-based compounds.
Water spot removers are a more extreme example of acidic car care formulations. Water containing high mineral levels (often referred to as 'hard water') will leave deposits on clear coated surfaces as the water itself evaporates. The acidic nature of water spot removers works to break these minerals down, allowing reasonably fresh water spots to be wiped away.
Lastly, pH-neutral shampoos generally do not alter the pH levels of whatever it is that your paint is contaminated with; this means that they have very little cleaning power on their own and are intended to act as a buffer of sorts between whatever is under your hand (mitt, pad, or towel) and the clear coat itself. In other words, they are meant for lubrication. They're often safe in the sun as they contain few to no harsh detergent ingredients that when heated or removed from water can leave deposits behind. The pH-neutral shampoos also generally rinse away more easily because they haven't emulsified any grime underneath.
Now that we've covered the boring [but necessary] chemistry behind car shampoo, let's dive in to whether or not it's worth letting them dwell on your paint before washing; AKA, the practice of foaming.
Don't Dwell On It | When Foaming Isn't Useful
Based on our experience with each product we offer and their exposure to hundreds of client vehicles, we can definitively say that the effectiveness of foaming/pre-soaking a vehicle is largely dependent upon how it's protected.
Using the information surrounding pH levels and shampoo formulations, you can begin to piece together an anecdotal conclusion that using the proper shampoo formulation and allowing it to dwell on the paint is beneficial overall, though the benefit may only be incremental when placed in a hierarchy of car care processes (mechanical decontamination with clay, hand washing, etc).
However, as with most processes, there are variables that will determine whether or not you get the most out of the ounces of shampoo you'll use to foam your car.
The first variable that's often overlooked: Inorganic protection, otherwise known as a coating. If your car is properly coated with a quality product, the chances that foam will dwell long enough to do its job are quite low.
Proper ceramic coatings like NV Nova Evo or NV Nova Pro bond with the clear coat of your vehicle, and unlike waxes, cannot be emulsified or broken down chemically. Because they are designed to evacuate water and most other liquids from the surface, you'll notice that car shampoo quickly runs off the surface.
Little to no dwelling time means little to no cleaning time.
You can see a clear example of this phenomenon in a photo of this BMW coated with NV Nova Evo:
Moreover, properly coated vehicles are often far less susceptible to contaminants bonding with or becoming embedded in the clear coat; meaning that most pH-neutral shampoos will have no issues carrying them away when combined with a mechanical agitation by a plush wash mitt or wash pad.
Why add an additional costly and time-consuming step (foaming) to your washing process when your ceramic coating is doing most of the heavy lifting for you?
Well, for one, foaming looks pretty. We won't argue with that sentiment. We aren't suggesting that foaming a coated car is completely useless, however, you won't be taking full advantage of the surfactants/detergents in whichever shampoo formulation you've chosen as most coated cars simply don't require much chemical assistance to be cleaned.
One could argue that a coated car covered in road grime, bugs or otherwise would benefit most from chemical intervention, as those contaminants aren't embedded within/bonded to the clear coat. The problem here is that while shampoo/foam may loosen or in rare cases, eliminate that contamination, there is virtually no efficient way to guarantee that your car's paint is free of grit/grime before moving to the drying phase, which presents a significant risk for love marks and isolated deep scratches induced by grinding that remaining grit into the paint. If you've invested your own time & money into polishing your paint to a high standard (or having a professional complete the process), why risk it?
Simply put, even cars with formidable protection require mechanical intervention (hand washing). That brings us to the next claim; that foam is a necessary layer of lubrication for washing.
Dissecting Claim #2 | Foaming as a Method of Adding Lubrication
This is where both coated and non-coated vehicles can benefit from a layer of foam being introduced prior to a wash, assuming that foam isn't rinsed away prior to the vehicle being touched with a wash mitt, wash pad or microfiber towel.
Imagine for a moment running a dry cotton towel across your cheek; it would often chafe your skin, leaving it red and irritated from excess friction.
This is why we use facial cleansers - or minimally, water - to wash our faces. It's also why us humans use shaving cream prior to introducing steel blades to our skin.
Paint - specifically, clear coat - isn't unlike an inorganic skin for our vehicles. It's porous, protects from harmful UV exposure, and is the first line of defense from harmful chemicals/contaminants.
While you could technically cleanse your face or shave your skin without shaving cream or a cleanser, it would be unpleasant and likely leave behind tiny abrasions, whether visible or not.
This is where the argument for/against foaming your paint prior to washing - for the purposes of lubrication - becomes incredibly granular, if not a bit petty. Add to that the fact that there is no efficient or scientifically useful way to measure lubrication factors, and we have ourselves a highly subjective debate.
Dunking a plush, high-quality wash mitt in a bucket of properly diluted car shampoo and water will create a barrier between the microfiber material and your clear coat.
Using a foam cannon to cover all of your car's surfaces in thick shampoo effectively accomplishes the same thing, only lending a barely perceptible addition of shampoo between the paint and your wash mitt. Is that barely perceptible addition worth the extra 2-5 minutes and monetary cost of the foam cannon plus the extra shampoo?
If you're expecting a definitive answer here, we can't give one. Why? Because variables that can't be efficiently measured (even if they can be effectively measured somehow) are best left to subjective decision-making. It comes down to how much time and additional money you're willing to spend in caring for your vehicle properly.
In our experience over the years, our take is this: It's worth taking the extra few minutes and spending a few extra cents per wash on sensitive finishes ('soft' paint or classic vehicles that don't have much clear coat remaining) to work towards preventing the minor clear coat damage which may take place with a hand wash. Even imperceptible marring or light scratches add up to a finish that will eventually need to be polished to look its best and accept proper protection; meaning that clear coat will need to be removed, and clear coat is finite. That's why we take every step possible to mitigate clear coat degradation. We have no real way of quantifying the effect of the process, but it's essential to the survival and differentiation of our business not to stop at 99% effectiveness - we chase the final 1% and often delve into the unnecessary to achieve it.
Not everyone reading this is a professional detailer, and if you aren't being paid to complete work for others, spending money on quality car shampoo may not be a ritual you find satisfying or useful beyond 'getting the job done.'
If you're working on a leased daily driver or a vehicle that is often exposed to harsh elements and will eventually need to be polished (by yourself or a future owner), so long as you're getting great results and using the two-bucket wash method with quality mitts/pads and dirt locks, why should you concern yourself with the extra 1%? In other words, "if it isn't broken, why fix it?"
That's a question you'll have to ask yourself, but if you ultimately decide that the final 1% is a pursuit worth taking on, we'll ensure that you have the best possible experience and chance of completing effective washes with proper equipment and materials.
In our next blog post, we'll discuss what makes thick, rich foam and how to identify issues that may be causing runny or ineffective pre-wash shampoo concentrations.