How to Prevent Streaks When Pressure Washing

To prevent lines and streaks when pressure washing, start by working in smaller sections that you can readily identify. When applying detergents, use a low-pressure spray pattern, and allow the detergent to soak on the surface for several minutes before rinsing without letting it dry. If you’re trying to avoid streaking on a vertical surface, apply your detergent from the bottom and slowly work upward using sweeping horizontal passes to prevent streaks caused by runoff, and then rinse from the top back down.

What Causes Pressure Washing Streaks?

Several different factors can cause pressure washing streaks, so there’s no clear answer to point to. Some of the most common causes of pressure-washing streaks include the following:

  • Using the wrong tip that cannot effectively clean the stain at hand
  • Not pretreating a stubborn stain before attempting to wash it
  • Using an improper or inconsistent spraying pattern and technique
  • Using a surface cleaner in a flooded area
  • Using the wrong kind of detergent on a surface or stain
  • Moving too quickly when washing
  • Not using enough gallons per minute

Does Surface Material Matter?

Pressure washers can affect different materials in different ways. When it comes to leaving lines, the type of material a surface is made of generally doesn’t influence whether or not pressure washing will leave streaks.  You could leave streaks pressure washing your mattress if you’re not careful.. However, some materials, such as wood, may be more prone to damage from application and due to streaking.

Depending on what causes the streak, pressure-washing streaks in wood surfaces can penetrate deep into the wood and will not be as easy to remove. In some cases, depending on how deep the stain is penetrated, you may need to sand down and effectively resurface the wood. This can be time-consuming and expensive for larger areas, such as decks and other floorings.

How to Avoid Streaks When Pressure Washing

As mentioned previously, there are several common mistakes that you may make that can leave streaks behind after pressure washing. Thankfully, there are several simple steps that you can take while pressure washing to leave a surface streak-free clean. To avoid streaks while pressure washing, keep the following tips in mind:

Pretreat and Soak Any Stains

If you’re trying to pressure wash a stain or other stubborn build-up on a surface, begin by soaking the surface, with or without detergent, depending on the stain and material, and let it soak for a few minutes without drying. Pretreatment can help loosen and break up dirt, grease, and grime, making cleaning easier when you go to pressure wash the surface.

Use Proper Spraying Technique

If you use a detergent, apply it from the bottom up on vertical surfaces, and rinse from the bottom back down. Utilize slow sweeping horizontal strokes to avoid any streaks from the runoff, and be sure to move at the right pace — not too fast or too slow. Most people get impatient and move too fast.

Use The Right Nozzle

Using the wrong nozzle while pressure washing may result in streaks. This is because the nozzle cannot clean the surface or stain properly, or it can cause you to use too much or too little pressure for the task.

Adjust Your Spray Angle

Another important thing to remember while pressure washing is to use the right spray angle for the stain and surface you’re cleaning so you’re using the right amount of force. For more stubborn stains, this means keeping the nozzle perpendicular to where you’re washing for maximum pressure application.

What Chemicals to Use That Help Avoid Streaks

Several chemicals are commonly used in both professional and at-home pressure washing, including degreasers, detergents, cleaners, rust removers, mineral deposit removers, and efflorescence removers. Using the right chemicals mixed in the right ratios, applied properly on the appropriate surface and stain, you can easily avoid lines while pressure washing

Some of the most common chemicals used in pressure washing cleaning include the following:

  • Bleach – A combination of sodium hydroxide and sodium hypochlorite, bleach is excellent at sanitization and disinfection. It can be powerful and shouldn’t be used on metals like brass, copper, and stainless steel, and you should also avoid using it on porous wood and delicate stone surfaces.
  • Ammonia – This is a natural gas made up of hydrogen and nitrogen atoms with a distinct, pungent, and irritating odor. It is an effective alkaline cleaner and is safe for more delicate surfaces like stainless steel.
  • Oxalic acid – This organic compound is naturally found in various sources, including fruits and vegetables. It can act as a bleaching agent and effectively remove rust and clean stone.
  • Citric acid – This is another organic compound that naturally occurs in citrus and is great for removing rust, mildew, and water stains. Like oxalic acid, its isolated form acts as a powerful bleaching agent used for sanitizing, disinfecting, and cleaning various surfaces.
  • Sodium hydroxide – Sodium hydroxide, commonly known as lye or caustic soda, has been a common component of soaps for centuries. As a result, it is a common component of many commercial pressure-washing detergents and cleaners.
  • Sodium hypochlorite – This is a solution that results from the reaction of adding chlorine to a sodium hydroxide solution. It is excellent at disinfecting surfaces and effectively removes stains as well. 
  • Potassium hydroxide – This is an inorganic compound commonly known as caustic potash. Its caustic nature has made it a staple of liquid and soft soap formulations for decades.
Sodium Hypochlorite is a favorite amongst professional pressure washers to pre-treat tough stains

Organic/Natural Solutions

If you’re looking for more natural, eco-friendly, or less harsh chemicals to use while pressure washing, there are some options available. For lighter jobs or removing basic dirt and dust, you may not even need any chemicals at all to complement the cleaning of the high-pressure stream. For some jobs, you can consider adding vinegar, an effective cleaner, disinfectant, deodorizer, and mold remover. 

While some of you may not want to use any chemicals, compounds like oxalic and citric acid are natural organic compounds. They are often derived from natural sources like fruits and are safe to use on a wide variety of surfaces.

Does the PSI Level Matter?

Your PSI is essential to any effective cleaning job when pressure washing. Pounds per square inch, or PSI, measure the force the water is spraying at. Simply put, a higher PSI means the pressure washer is spraying with greater power.

To prevent leaving streaks behind while pressure washing, you want to use the right pressure for the stain and surface you’re working on. Using too high pressure can damage surfaces, which could potentially cause streaks, while using too low of force may not effectively remove stains and runoff, also potentially causing streaks.

Does a Pressure Washer Surface Cleaner Leave Streaks?

A surface cleaner is a specialized pressure washer attachment that evenly sprays through the bottom of an enclosed disc. They feature a spinning arm with small nozzles that produces an even, smooth cleaning path. When used properly, it’s an excellent way to pressure wash without leaving any lines behind.  Also try running over the surface using small circular or figure 8 patterns shown in this video:

However, while largely effective at avoiding streaks, they may be left behind if you make mistakes during your initial pass, such as going too fast or not using detergent on a stain. Furthermore, avoid using pressure washer surface cleaners on decks and other wood. The pressure intensity and spray pattern of these attachments can readily damage and splinter the wood itself, and using the wrong detergent could seep into the wood and ruin it.

What Do I Do About Streaks Already There?

If you’ve already pressure-washed a surface and left streaks behind, there are some potential fixes depending on the surface at hand and how it was created. One of the simplest solutions, if they are light and not aesthetically unappealing enough, is to leave the stains and let the surrounding surface darken over time.

However, when it comes to more significant lines, there are other options you can use. For example, if you can figure out what caused the streaks after the initial pass, you could just run another pass while avoiding whatever caused the mistake to see if that helps. This technique is most effective if a difference in cleanliness causes the streaks because this won’t work if they are caused by surface damage.

If the streaks were caused by using the wrong nozzle that may have concentrated the stream on too narrow of a point, you could swap out for a nozzle with a wider spray area and wash the area again. This is an excellent fix if you only need to take care of a smaller area or spot wash, and it is much faster than needing to rewash the entire area.

Hard to Remove Streaks

If the lines are too stubborn to be removed by the steps outlined above, consider acid washing your cement or other surfaces if it can stand up to the process. First, spray a diluted chemical like hydrochloric acid or muriatic acid over the entire surface area until it is fully damp, then brush the cement to help agitate any stains. After application, let it sit for 10 minutes to fully etch the surface, and then scrub any remaining residue with a large brush and rinse thoroughly.