Pressure Washing

Pressure Washing Prepping for Sealer application

Pressure Washing

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Pressure washing is a generic term for cleaning many different types of items using high pressure water. Mostly pressure washing is perceived to be done outdoors, but you would find that much is done indoors as well. Items you may be most familiar with are House Pressure Washing and Concrete Pressure Washing.

How does Pressure Washing work?

The pressure creates agitation which is a result of pressurized water getting in behind a piece of dirt or contaminant and hydraulically forcing or pushing the dirt away from the surface. Depending on the spray pattern and size of water droplets you may be able to cause a mini explosion when water droplets hit the surface.

Pressure Washing can be handy, but watch out!

While pressure washing can be a handy way to clean it is also important to understand that many contaminants are able to bond or take root to a surface. Such a bond can be stronger than the surface, so you could remove the substrate along with the contaminants and this might be a bad thing. In cases like this it might be a good idea to apply a detergent that will break the bond of the contaminants. This way less force is used and no damage is caused to the substrate.  Common contaminants found here in Nashville, Tennessee include mildew and hydrocarbon emissions. A strong bond can exist with both of these culprits. An example would be mildew stained concrete. The amount of pressure it would take to penetrate deep where the roots would end could remove the top layer of concrete along with it. This would not be a sustainable way to maintain your concrete.

Pressure Washing Safety

I don’t recommend amateur pressure washing by an untrained or inexperienced person. Always wear personal protective equipment and keep all people and animals at a safe distance.

Pressure Washing with detergents

Pressure Washing with detergents will help prevent damage, but your pressure washer will also want to control the pressure and water flow. There are many detergents available. It is important to understand what detergent is needed to remove your particular contaminant. It is also very important to choose a detergent compatible with your substrate. Much like you wouldn’t want to pour bleach into a washing machine loaded with color fabrics. These detergents will contain ingredients and it is important to know what you can or can’t use it on. You could get lucky the first time, but if using the wrong stuff you could find out the hard way next time. This is because some surfaces can handle occasional use of a certain ingredient, but not chronic use. Some detergents work well on mildew while others work well on hydrocarbon emissions. Both are very common and possess a bond resistant to high pressure. Even on concrete, but especially on wood.

Water pressure and flow when pressure washing

It is important to adjust water pressure and flow according to the pressure washing job being performed. The right combination of pressure and flow can speed things up, but too much or too little can slow things down… way down. The pressure washers found in most big box stores usually have too much pressure and not enough flow. The later is more common. Without enough flow you will find that the dirt is just swirling and kinda’ just hanging around. Too much pressure will cause damage and premature wear.

Use the correct Pressure Washing nozzle

Nozzle size and pattern are very important. The nozzle orifice controls flow and pressure. The nozzle pattern controls the many variable patterns angle and sizes. Using the right nozzle will help you not only get the correct pressure and flow, but the right pattern angle and cleaning foot print. The correct combination of all three will create the right size droplets and velocity to create that mini explosion when needed.

Whether pressure washing  house siding, a deck or concrete it is always important to have an experienced person to supervise and perform such a task.


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