There’s a longstanding debate about this subject in online auto forums, because cars are expensive and nobody wants to damage their paintwork when washing their car with a pressure washer.
The majority of experts with decades of experience washing cars have concluded that pressure washers do not damage paint on modern cars – provided they’re used correctly and at the right pressure, which is between 1200 – 1900 PSI.
We’ll explore the reasons behind this and how to wash your car safely within this article. If you take certain precautions you should be fine.
What PSI Will Damage Car Paint?
It’s important to start by considering what a safe pounds per square inch (PSI) is for car washing sprays – as the power of your pressure washer is at the heart of this issue.
While some commercial pressure washers are as powerful as sand blasting machines, and can even be used to strip engine components back to raw metal – all over-the-counter washers designed for home car use are only powerful enough to wash off dirt and grime once you have rinsed and soaped your car first.
And while it’s certainly true that overpowered commercial pressure washers would strip the skin off your hand (or potentially worse), this is not the case with models made for car washing. The former should obviously never be used on autos.
Indeed, you will often see squashed black bug marks left on your license plate after using your home pressure washer, because the spray PSI isn’t sufficiently strong to remove smudged in greasy marks like these. This means you often have to rub these off by hand which can be frustrating.
Therefore, as mentioned above, an electric pressure washer with an output of 1200 – 1900 PSI should be perfectly safe to use on the baked-on paintwork of all modern cars, even at the top end of the PSI scale.
Won’t Chipped Paint or Rust Spots Mean High Pressure Water Will Strip Off My Paintwork?
It’s a common misconception that if the paintwork on your car is chipped or has a few rust spots – then your domestic pressure washer will strip off larger chunks of paint when the water gets underneath.
Firstly, as modern car paint is baked on at extremely high temperatures, your home pressure washer will be nowhere near powerful enough to do this. It’s also advisable to treat, touch up and wax any paint chips or rust spots before you wash your car anyway.
Secondly, you should never point the concentrated high pressure spray directly at just one spot on the paintwork for more than just a fleeting glance. The jet itself should always be pointed at your car at an angle of around 40-45 degrees and a distance of 2-4 feet to minimise its power.
So you need to make sure you use your pressure washer the correct way – but more on that below.
What About Classic Cars?
The only caveat to all of the above is if you’re cleaning an older classic car. The paintwork on older car models was applied using different processes, so it will be more sensitive to the use of pressure washers.
However, for modern cars with modern paint jobs (including high end models), an over-the-counter pressure washer with a low to medium PSI range should not present any risk to your paintwork at all.
Choosing a Washer That’s Safe For Your Paint Job
There’s a huge choice available when it comes to buying a car pressure washer, and while we’re not going to recommend any specific models here – we will consider what features to look for in terms of protecting your paintwork.
- Buy cheap, buy twice – invest your hard earned money in a quality model from a quality brand. Going cheap will leave you with weak and intermittent water pressure and flimsy hardware that may encourage you to use the nozzle too close and in the same spot for too long.
- Get a model with a long hose – when I was a teenager my folks used to pay me to wash the two family cars. I once ripped the license plate off our Volvo because the hose was too short and I yanked it too hard. Make sure you get at least 5-10 meters of hose as shorter ones can also scratch your paintwork too.
- Buy a model with a built in detergent container – then you can use the right car soap for the pressure washer and this will help you wash your car properly (more below).
- Take into account Gallons Per Minute (GPM) – the ideal range for a home car pressure washer is 1.4 – 1.6 GPM, as this should regulate the water flow to your nozzle in a measured and consistently powerful way. This is actually very environmentally friendly too.
- Choose an electric model not gas – the latter can be overpowered and more unpredictable, so get an electric one with loads of cable.
- Don’t worry too much about the different types of nozzles – over-the-counter car pressure washers come with a variety of nozzles that produce various spray patterns. It’s best to avoid the dirt blasting pulse sprays and focused pencil jets and just choose the standard fan spray, as we’ll want to control the spray angle and motion ourselves in order to protect the paintwork.
- Make sure your model comes with a brush attachment – we’ll be needing this to wash your car safely and properly.
Pressure Washing Do’s and Don’ts (To Protect Paintwork)
Here are some key do’s and don’ts when washing your car safely and effectively with a domestic powered pressure washer.
Pressure Washing Do’s
- Wear the proper clothing, including boots, overalls and gloves.
- Check all the doors and windows on your car are closed
- Start washing from the ground up so you avoid streaks of grime.
- Set your pressure washer PSI to between 1200 – 1900, with a GPM of 1.4 – 1.6.
- Use a standard fan spray nozzle, with a straight angle.
- Use a pressure washer with a built in soap container, and the manufacturer’s recommended soap to go in it.
- Manually angle the spray at 40-45 degrees and keep it around 2-4 meters away from your paintwork.
- Spray in a fluid motion not lingering on any one spot for too long.
- Keep your brush attachments clean of grit and grime so you don’t scratch your paintwork.
- Use a high quality electric pressure washer from a reputable brand.
- Wash your car in specific steps to protect your paintwork (more below).
Pressure Washing Don’ts
- Don’t wash your car on a gravel drive as your pressure washer can send stones flying up to chip your paintwork. If you do then really take care not to point the high pressure spray at the stones (or your feet).
- Don’t use a cheap model with a short hose that can scratch paintwork or rip off your license plate
- Don’t point the spray just a few inches away from the paintwork and stay in the same position for several seconds (especially on door seams and light fittings). Keep things moving.
- Don’t open the doors or hood and try to spray the engine or anything inside.
- Don’t mess around and try to spray your family members, friends or pets as a joke.
Washing Your Car Safely & Effectively With a Pressure Washer (In 4 Simple Steps)
Let’s now consider the steps you need to take when washing your car with a pressure washer – so we protect that all important paint job.
- Rinse – start with a preliminary rinse-off to get rid of any large or obvious chunks of mud and dirt, and to prepare the paintwork for the soaping stage next. Remember all the precautions mentioned above.
- Soap – using the built in detergent container and the soap recommended by your pressure washer manufacturer or car maker, thoroughly spray detergent foam over the entire car. Let the soap sit for a while to do its work breaking down grime and grease, then gently brush over any problem areas of dirt (such as the sills and door bottoms) with your brush attachment. Do this from the ground up to avoid streaking.
- Main spray wash – following all the guidance above, it’s now time to remove the detergent container and start spraying off the car for the main clean. Work in constant fluid movements and do not get too close or linger too long in one spot. Pay particular attention to the wheels and wheel arches where the most dirt can collect, and work methodically from bottom to top again.
- Dry – to avoid streaking when drying, it’s a good idea to dry your car using a high quality chamois leather. These are very soft and extremely absorbent – and provided they are clear of dirt and girt will not be a problem for your paintwork. Using uniform movements, pull the chamois towards you or downward over the surface of the car until the leather is soaked. The simply ring it out and repeat this over the whole vehicle until it’s completely dry.
In addition, you can now wax your car if you like when it’s completely dry. This will further protect your paintwork from water ingress, dirt and grime when out on the road.
In summary, it is safe to use an over-the-counter pressure washer to wash your car – and if you choose the right model and use it correctly, you will not damage your paintwork.
By adhering to a few simple rules and washing your car in a specific way, there is no reason why you can’t successfully and safely wash your car for years to come using a specifically designed home pressure washer.
And while there’s nothing at all wrong with choosing to wash your car by hand with a garden hose pipe – it’s just not as much fun as getting to work with a pressure washer!