To remove pressure washer marks from a deck make an assessment of the type of material that the deck is made of. Before starting the procedure, make sure to protect the vegetation and the objects present in close proximity to the deck. If the deck is made of concrete, remove all the dirt and dust using a broom or a vacuum cleaner. Apply muriatic acid to the entire surface, brush it, and rinse it right away to avoid damaging the deck. In case the deck is made of wood, swipe away the debris and dust, and apply specially formulated chemicals for wood restoration. Attach a low-pressure nozzle to a pressure washer, choose the right PSI levels, start the cleaning unit, and rinse the chemicals off the deck.
The steps required to remove pressure washer marks from a deck are discussed in detail below.
- An electric pressure washer, gas pressure washer, or a portable pressure washer
- A low-pressure nozzle tip for the power washer
- Chemicals specially formulated to restore wood decks
- Muriatic acid to restore concrete decks
Prepare the Area
Before removing pressure washer marks from a deck, protecting the plants and the irremovable nearby objects is required. Cover the vegetation in close proximity to the deck with a tarp to avoid contaminating it with harsh chemicals and to prevent damage due to high pressure. Even if a fully biodegradable chemical is used, it is highly recommended not to skip this step. Do the same with items that can not be removed, like outdoor furniture.
Remove Pressure Washer Marks from Concrete Decks
Step 1. Remove Dust from the Concrete Deck
This step can be performed either by vacuuming the concrete deck or by brushing the dust away. The vacuuming procedure is more efficient as it ensures a dust-free surface. If a vacuum cleaner is not accessible, the brushing procedure should be repeated until the surface is clear of dust and debris.
Step 2. Apply Muriatic Acid to the Concrete Deck
To correctly remove stripes left on a concrete deck by pressure washer operation, using muriatic acid, also known as hydrochloric acid, is recommended. This acid is capable of etching the cement surface and removing the marks caused by power washing the deck. Muriatic acid can be used only outdoors as it can lead to gas intoxication indoors.
This procedure can cause serious harm to the respiratory system of the operator. The use of a respirator that is equipped with an acid-grade filter is recommended. Using safety goggles that are vapour proof and gloves that are resistant to acid is also indicated as a safety precaution. Wear an apron designed to be acid-resistant for body protection.
If the deck presents stains that need to be removed make sure to avoid using a cleaning solution that contains Trisodium Phosphate, as the gases that result from combining these two chemicals are harmful to human health.
Mix 4 parts water and 1 part muriatic acid in a plastic bucket. Apply the resulting solution by spraying it evenly to the surface.
Step 3. Scrub
While performing the scrubbing procedure, make sure to move quickly to avoid prolonged chemical exposure. This step is required for evenly distributing the muriatic acid throughout the surface and to help it adhere better to the concrete surface. Avoid letting the muriatic acid dry on the concrete as it can cause permanent damage.
Step 4. Rinse
The recommended way to rinse muriatic acid from concrete is without the use of a power washer, as high-pressure levels can determine the acid to penetrate deeper into the surface and destroy it, leaving deep marks.
If using a pressure washer is the only option, equip the unit with a low-pressure nozzle tip. This type of pressure washer nozzle is a good choice for rinsing any type of surface because it has a gentle spray. Set the power washer to the lowest PSI possible. The preferred level is around 500 PSI.
Remove Pressure Washer Marks from Wood Decks
Step 1. Swipe Dirt and Dust
Removing dirt and dust off the wood deck is essential to make sure that the chemicals adhere well to the surface. This procedure can be performed using a broom or a vacuum cleaner.
Step 2. Apply Chemicals
A solution that will remove pressure washing marks from a wood deck will have an effect on making the entire surface have the same color. Apply this solution evenly until the whole deck is covered. Leave the chemicals to soak in for as long as indicated by the manufacturer and not longer. This process might take a few hours, depending on the brand. Read the label carefully before beginning the procedure.
Step 3. Attach the Nozzle
Before turning on the pressure washer, make sure to attach an appropriate nozzle. This nozzle will be used only for rinsing, and it should be designed for low PSI. More information on choosing the right nozzle can be found in our detailed article on pressure washer nozzles. Remember not to turn on the water supply or the engine of the pressure washer before attaching the nozzle, as it can lead to severe injury.
Step 4. Choose the Right PSI
Wood is a sensitive material that can easily get damaged during a pressure washer cleaning job. The recommended PSI for pressure washing wood is under 1500 PSI. Choosing a pressure washer that can deliver low PSI levels is recommended, as pressure levels above this value can damage the deck even further. Power washing a deck made of soft wood requires around 500 PSI, while harder types of wood can withstand up to a maximum of 1500 PSI.
Step 5. Rinse the Chemicals Off the Wood Deck
To remove pressure washer marks from a deck correctly, keep the nozzle at a distance between 12 and 18 inches from the surface. Try to rinse the deck at the same pace without skipping any sections, as skipping a section will make the color of the deck uneven.
Causes of Pressure Washer Marks and How to Prevent Them
Pressure washer marks often occur with beginners. Once an operator has left marks on a surface using a power washer, they will know what to avoid doing. These marks are the result of an error in operation and do not occur randomly. Knowing what to avoid is essential, as high pressure can create permanent damage which can require high investment to repair.
Pressure washer marks are due to the following operation mistakes:
- Not having a cleaning system
Cleaning a deck with a pressure washer requires splitting the working area into smaller cleaning sections. The purpose of this action is to avoid overpassing an area that has already been cleaned. Not splitting the surface into smaller cleaning sections might lead to an uneven deck color, as some parts are left unattended.
- Applying too much pressure
Pressure washing a deck while using a higher pressure than required will lead to damage to the materials that it is made of, either if we are talking about a wood deck or one made of concrete. If the operator is not familiar with the pressure washer or with cleaning a certain type of surface, the most common mistake is to apply high pressure to remove stubborn dirt. Cleaning a deck without using pressure washer soaps or detergents does not always deliver deep cleaning.
- Not rinsing chemicals in time
Chemicals that have not been rinsed in time and are left to dry onto the deck will leave marks regardless of their type. Rinsing the cleaned area thoroughly is highly recommended, especially if the cleaning job is performed under direct contact with sun rays.
Apart from chemicals drying, another damaging factor is how the used detergent changes its action when it is heated at high temperatures. Sun rays are capable of heating detergents to extremely high temperatures, which might lead to permanent discoloration, especially on wood.