High or low pressure, which is better?

Ok, so my question is which is better for limiting scratches, using a pressure washer or just a low pressure nozzle like the fire hose nozzle?

Correct me if I'm wrong but I feel like...

Using a pressure washer after foaming would help remove more dirt before washing, thus reducing the chance of scratching during the normal wash process, BUT the high pressure may cause marring by driving particles into the paint.

Using low pressure after the foam wouldn't get as much off as a pressure washer, thus increasing chances of scratching from normal washing, BUT the low pressure won't drive particles into the paint as much.

which is better? I'm trying to develop the best washing routine to limit scratches, b/c doing a full polish is a pain in the ass, and I'm not sure which of these methods is the best.

 

i usually use a pressure washer first to give the initial rinse of the vehicle then proceed with foaming.

I find that it works great but i don't use a pressure washer every single time.

 

When using foam cannon, the viscosity of the product plays a huge part in how much foam is obtained and how much product is used. The foam starts loosening and lubricating the paint immediately, thus gentle touch washing with a soft mitt substantially decreases the risk of micro-marring because the paint is covered in a layer of lubrication. Its other advantage is that the surface isn't 'touched' as much as in hand washing

High Pressure Foam Lance

The benefits of using foam cannon with a pressure washer is you can coat the whole vehicle in soap (lubrication) while loosening a lot of dirt at the same time, and its must quicker than a conventional wash uses less water. The Foam Cannon work with a pressure washer, it delivers a mixture of water and soap through the tip at high pressure.

Pre-soaking a paint surface is proven to be an efficient method to loosen surface oil, grease and road debris; along with proper washing technique, utilizing a two-bucket with Grit Guard™ system.

 

I thought this is the point of using a foam cannon, to remove loose dirt and grime before actually washing to minimize the chances of scratches and swirls.

I usually foam up my car with my foam cannon and pressure washer, let it dwell for a couple of minutes, and then rinse everything off, then proceed with a regular wash.

The pressure washer is more effective at removing loose dirt and grime than a regular hose, but sometimes I don't feel like breaking out my pressure washer, so I just use my foam gun and hose. Then I proceed with a normal wash. Some people like to foam up the car and go straight to washing (without rinsing), which helps lubricate the surface, but this is just personal preference.

I was under the impression that any touchless cleaning done with just water and a foam gun/cannon does not instill scratches and swirls.

 

A foam cannon loosens the dirt, then you use a pressure washer to remove it. A pressure washer would be more effective at removing dirt than a low pressure hose, but the high pressure would drive the dirt into the paint more, increasing risk for scratches.

I'm trying to find which process would yield the lowest risk for scratches:

rinsing the foam with high pressure, then washing. Which removes more dirt than low pressure to minimize scratches during the wash, but drives dirt into the paint more
OR
rinsing the foam with low pressure, then washing. Which removes less dirt than high pressure, increasing risk of scratches during the wash, but doesn't drive dirt in to the paint nearly as much.

On DetailedImage.com this guy says not to use high pressure

“First you want to pre-rinse the surface to remove as much of the dirt and debris as possible. Try to avoid using a strong stream of water as the pressure on heavy particles can potentially scratch the paint.”

How To Properly Wash and Dry a Car – Detailed Image

And Togwt says in his Washing and Drying segment not to use high pressure either, right under “Methodology”:

“To reduce the risk of scratching paint finish start by thoroughly rinsing the vehicle to remove loose surface dirt and grime, use a gentle spray (Ultimate Nozzle) you don't want to cause impact abrasion to the paint surface, take your time and be careful and you'll avoid paint damage.”

http://www.detailingbliss.com/forum/detailing-school/7798-washing-drying-vehicle-paint.htm

 

I think you are being really technical. When I have lots of mud and grime on my car, I feel the safest way to remove it is to turn up the pressure on my Karcher and just blast all the crap off at close-range. I could be totally wrong, but fortunately I drive a Subaru not a Ferrari so I'm really not that concerned.

 

you're probably right, I just read alot of things that contradict each other and want to get some insight from people here. I have a Subaru too lol, but I just want to keep it as nice as I can.

 

What model? Looks like an 08+ Impreza Hatchback. 08 WRX Sedan here. :applause2:

This is one of those things where you'll never get a truly straight answer because it's hard to come to any factual conclusion. I can tell you that if pre-rinsing isn't safe, then we would all just start washing our cars on a completely dry vehicle. Water acts as a natural lubricant.

 

Yep 08 impreza. that's sweet you got the WRX they are pretty quick, I really wanted one but the insurance was way to high, it's too much already as I'm only 19

 

Gallons per minute is much more important than psi. I recommend to have more than 2.0 gpm for detailing.

John

 

This is a splitting hairs type argument imo... using a pre rinse and foam soak down is going so far beyond most wash techniques as it is....