Soft Washing: How To Use Low Pressure Sprayers for Mold Remediation

Have you ever wondered why, despite your best efforts, mold develops outside your home? Mold forms on vinyl siding, fences, decks, outdoor furniture, rocks, and concrete when moisture is present near the surface, allowing the unsightly biological material to grow. For moldy surfaces near the edge of your house, you can check to make sure your gutters aren't overflowing or dripping water on your siding, sidewalks, or furniture. You can also look for damaged water lines, gutters, etc. that are causing wet scenarios. Any damaged siding may be allowing rainwater to become trapped behind the siding material, providing the perfect environment for mold or mildew to thrive.

How To Clean Moldy Vinyl Siding

The reality of mold is this: while some mold can be removed from your home through regular scrubbing, it cannot be totally eradicated without the use of proper chemicals: bleach (sodium hypocholorite). The most essential thing is to respond quickly to a mold problem in order to lessen the severity of the situation and maintain the integrity of the material upon which the mold is growing.

Soft Washing Methods for Outdoor Mold

While most people are inclined to use a pressure washer to remove mold, pressure washing can damage materials like flagstone (pictured below), wood, fabric, or vinyl siding due to the high pressure. Even 1,000 psi can harm many surfaces, and even if the dirt is removed, the damage has already been done.

Flagstone Soft Washing Before and After

The proper method to apply bleach on these sensitive surfaces is to use a low-pressure (50 to 100 psi) sprayer to clean without causing harm from high pressure. FlowZone sprayers allows you to spray from 8 psi up to 115 psi. This is critical when spraying sensitive surfaces. Low pressure spraying is referred to as "soft washing."

Soft washing is a simple process. Simply mix up a 3-6% bleach mixture, spray the surface evenly with your backpack sprayer, wait 5 minutes for the bleach to kill the mold, and then rinse the surface down with fresh water.

Take care when spraying the bleach mixture to avoid spraying plants. It is best to cover the plants with a tarp before starting to spray. If you do get the bleach mixture on any flowers, grass, etc. simply rinse the plant thoroughly down with water to wash the bleach into the soil and off of the leaves of the plant.

Using Battery Backpack Sprayers to Clean Mold

One of the keys to even application of the cleaning mixture is a steady, regulated spray. Battery powered sprayers like the FlowZone Cyclone 3 or a FlowZone Typhoon 3, provide a consistent, even spray pressure so that you can apply equal amounts of bleach throughout the cleaning process.

Soft Wash Vinyl Siding

It is critical to have complete and even coverage. Pay attention to how you hold the wand and make sure you're spraying evenly back and forth to ensure every section is covered.

The Perfect Mixture: Bleach Cocktail for Outdoor Mold Removal

Before you begin to handle bleach, make sure to wear the appropriate personal protective equipment (PPE) to protect against any chemical burns or inhalation of mold spores that will be disturbed when you begin spraying. Gloves, safety glasses, and a mask are equipment you should wear during this job. Wearing a long sleeved shirt and pants avoids getting bleach or mold spores on your skin.

Creating and applying the bleach mixture can be done in just a few quick and simple steps with a battery backpack sprayer:

  • 6% diluted bleach (common household bleach is sold at 12% dilution, so you can simply use a 1:1 ratio of water and 12% bleach to achieve 6% dilution)
  • 2 tablespoons of dish washer soap (to act as a surfactant while the bleach is killing the moldy surface)
  • Spray down the surface and let the bleach mixture settle for 5 minutes
  • Rinse surface off with fresh water
  • Smile as the mold disappears

Hear it from a loyal FlowZone customer:

Written by: Connor Duffy
Last edited: January 22, 2024

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