How to wash a car with a pressure washer
Did you know that bird poo takes as little as 48 hours to damage the paint work of a car. This is because bird poo is acidic and with a pH of around 3-5 it is highly corrosive to car paint work. If left to dry for too long bird poo can seriously damage the exterior of your car.
In extreme cases it can degrade the paint and bleach the car in a bird poo shaped stain that can be very difficult to remove. We all like to drive around in a clean, shiny car. But almost no one wants to spend their precious freetime washing their car.
What if I told you there was a way to cut the time it takes to wash your car in half and have fun doing it? Interested? Then it’s time to get the pressure washer out.
Pressure washers are the most economical, environmentally friendly, and safest way to wash a car (if used correctly). They save water, time and money, without damaging the car like some other methods of cleaning cars can. Plus they are fast, which means you can get your car clean and still enjoy your free time.
Why Is It Wrong To Use The Automatic Car Wash?
You might be thinking “why not take it to the car wash?” Well firstly it takes petrol to get you there, secondly it costs money, and thirdly automatic car washes can seriously damage your car. The brushes that are used in car washes can easily snap car aerials and wing mirrors, plus you don’t even want to think about what’s actually caught up in those brushes!
From dirt, grit, stones, even tarmac in some cases. Automatic car washes might be easier because all you do is sit there, but how about the work needed to repair the paint work and/or mirrors and arial?
How To Pressure Wash A Car Correctly
There’s a right way and a wrong way to pressure wash your car, so let’s look at how to do it right.
Safety First
Before we start let’s have a quick look at safety issues to take into account.
Electricity
Consider how close the car is to an electrical socket, extension cables shouldn’t be used with a pressure washer, and could invalidate any warranty, unless the correct power breaker is used. So park as close as you can to the power source, allowing for water spillage, remember electrics and water do not mix well.
Clothing
Pressure washers create a considerable amount of spray, so if you don’t want to get soaked, it’s best to wear a waterproof jacket, and maybe think about welly boots. Definitely not open toed sandals anyway, at the very least, closed in shoes or trainers.
Pressure Washer PSI And GPM
A pressure washer works by combining water flow (GPM)and water pressure (PSI) to clean dirt and debris. The flow is measured in Gallons Per Minute and the average pressure washer has a GPM of 2. The pressure is measured in Pounds Per Square Inch.
The maximum PSi you should use on a car is 1900 PSI, this will stop you damaging the paint work.
Select The Correct Nozzle
Most pressure washers are sold complete with a number of different nozzles for different jobs.
Each nozzle is classified with a different colour and they have different uses.
Red Nozzle
The red nozzle produces the most powerful jet of water. So powerful in fact that it can cut clean through wood, and paint. It is also powerful enough to scratch paintwork. Definitely not one to use on the car.
Yellow Nozzle
The yellow nozzle has a 15 degree tip and is used for removing tough dirt. It has less power than the red tip and can be used on many surfaces, including, concrete, drains, roofs, and garage floors.
Green Nozzle
The green nozzle has a 25 degree tip and is mostly used for decks, patios, boats, and cars. It has a wide enough jet spray to clear leaves, yet gentle enough to be used on cars without damaging them.
White Nozzle
The white nozzle is the gentle option and has a wide spraying pattern. Giving maximum spray at low pressure and is definitely suitable for cleaning the car. In fact it’s probably best suited for car cleaning as long as the car isn’t too dirty. We advise starting with the white nozzle and if the dirt doesn’t shift then go up to the green nozzle.
Black Nozzle
The black nozzle has a 65 degree tip which is too soft for cleaning, and is usually used for prewashing, and applying detergent. Then you have to change the nozzle for rinsing properly
The chart below gives the values and uses for the most common nozzles.
| Colour | Degree | Use |
|---|---|---|
| Red | 0 | High pressure, cement and hard surface washer |
| Yellow | 15 | Removes dirt and strips paint from walls |
| Green | 25 | Good for cleaning hard surfaces like concrete free from debris,can also be used as a prewash and final rinse |
| White | 40 | Ideal for car washing, as it cleans large areas quickly. Great for rinsing detergents away |
| Black | 65 | Low pressure, detergent application |
Guide To Washing A Car With A Pressure Washer
Here’s the step by step guide to correctly and safely wash a car using a pressure washer.
Safety Reminder
If you are using an extension cable never use one that’s longer than 10 metres (30 ft) and use a Residual Current Device (RCD) for electrical safety cut out. It’s probably best to wear goggles to protect your eyes and gloves in case you are allergic to anything in the detergent (if using).
#1 Rinse The Car
To remove any loose dirt or debris start with a rinse using either the green (25 degree) or the white (40 degree) nozzle. Never use anything lower than that, as using the yellow or red nozzle will probably damage the paint work.
Before spraying the car, spray the jet washer onto the ground, to make sure it is the correct pressure.
Make sure your nozzle is no closer than 12 inches (30 cms) to the car as you spray.
Spray the entire car including the wheels.
Take care around mirrors, and lights etc. as these can be delicate and easily damaged. So it’s best to take a few steps backwards to lower the pressure when rinsing these areas.
Always angle the spray in a downward direction and avoid spraying directly head on as this might damage the car.
#2 Add Detergent
Always use a detergent that is suitable for both the car and the pressure washer. Most pressure washers have a container for detergent to make it easier to apply. If yours doesn’t apply detergent by hand.
Manufacturers have different ways of using detergents so consult your manual before starting
Use the black (65 degree) nozzle to apply detergent (many pressure washers will not use the detergent unless using the black nozzle).
Start spraying with the nozzle around 3 feet (90cms) away from the car, you can move in slightly closer to remove particularly hard stains or squashed insects.
To avoid streaking apply detergents from the bottom and work upwards.
You might have to get closer to get the wheels clean.
#3 Give The Detergent Time To Work
Check manufacturers instructions, but detergents generally need to left on the car for around 5-10 minutes
Don’t allow the soap to dry out on the car, this might mean intermittent spraying to prevent drying during the 5-10 minute soaking time.
If It’s particularly windy, or a very hot day, it’s more likely that the soap suds will dry out, even in such a short time span.
#4 Get Rinsing
After the soap suds have had time to do their magic, remove the black nozzle, and replace with the white (40 degree) nozzle.
Aim at the floor away from the car and spray, to remove all detergents from the system.
Then rinse the car starting at the top and working downwards.
Keep the nozzle around 3-4 feet (90-120 cms) from the car.
#5 Dry The Car
Some people neglect this step and allow the car to dry naturally, and this is fine. But if you prefer not to have streaks or spots after it dries, it’s best to use a chamois leather to clear all the moisture away.
Lay the chamois leather flat on the car, pull it towards you, once it’s full of water remove it from the car and wring it out.
Repeat this process until the car is completely dry, then wring out the chamois leather for the final time and allow to dry on a clothesline.
Once it’s completely dry return it to it’s storage pouch for next time.
Pack the pressure washer away after removing all the water and store in a frost free place.
That’s it, the car is clean and dry and ready for you to do whatever you want to do with it. I’m guessing it’s taken as long, if not longer to read this as it will to actually pressure wash your car.
