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How to Pressure Wash Fiberglass

Fiberglass is used in a myriad of different industries, from the automobile industry to the food processing industry. It’s pretty likely that you own some things that are fiberglass or they have fiberglass components, like boats, cars, RVs, roofs, and even windows. 

Last weekend, I decided it was time to tackle the grime on my fiberglass boat. As I set up my pressure washer, I paused, wondering if there was a right way to do this without damaging the surface. Have you ever stood with a pressure washer in hand, hesitant about the best way to clean your fiberglass surfaces without causing harm?

To pressure wash fiberglass effectively, use a low-pressure setting and a wide spray nozzle. Start by wetting the fiberglass surface with water. Then, apply a mild detergent solution, let it sit for a few minutes, and gently wash it off with the pressure washer. This method ensures thorough cleaning without damaging the fiberglass.

How to Pressure Wash Fiberglass

Since you need to exercise caution when pressure washing fiberglass, it’s important to know about pressure washing, fiberglass, and how to correctly utilize the two together. We’ll walk you through everything you need to know about pressure washing fiberglass, from what pressure washing is and what fiberglass is, to techniques for pressure washing fiberglass.

Steps to Take When Pressure Washing Fiberglass

Steps to Take When Pressure Washing Fiberglass

Fiberglass is really easy to clean. However, when you’re using a pressure washer for the job, you need to proceed with a little caution. Pressure washers can cause significant damage if used improperly. Follow these steps and take note of things to be aware of while cleaning.

Step one: Gather the materials

There’s a handful of things you’ll need for this task. A pressure washer, the right nozzle, some kind of cleaning solution, and maybe a washer attachment or two.

Go with an electric pressure washer

There are basically two types of pressure washers: electric and gas. Electric powered washers are quite common because they’re affordable. They provide just enough power to sufficiently clean most surfaces you see everyday.

Fiberglass components are often made to have a gel coat over them for protective purposes, Pressure washers that spray with too much water pressure can strip away the gel coating rendering it virtually useless.

Gas powered washers are much more powerful than electric ones. They are able to spray water at a greater pound-force per square inch (PSI). So, gas pressure washers are the preferred choice for tougher cleaning projects.

We don’t need to get hardcore to wash fiberglass. You can save some money and avoid some risks of damage when you go with an electric washer.

Choose the right nozzle 

Pressure washers utilize nozzles to direct the spray of the water and to manage the velocity of the water that comes out. Most washers come with a set of color-coded nozzles at the time of purchase. These colors are universally coded, so they mean the same on any washer. But that does not mean they’re interchangeable on any washer!

When you’re pressure washing fiberglass you’ll first use the black nozzle to spray on a cleaning solution. After the cleaning solution has soaked on the surface for 5-10 minutes, you’ll use the green nozzle to rinse off the cleaning solution and wash away any stubborn stains.

The black nozzle’s function is to deliver a low pressure spray along with a wide 65 degree spray pattern. It does this with because it has a large nozzle orifice. The design allows for easy application and coverage of soap or detergent. The cleaning solution is sprayed on and is allowed to properly adhere to the surface without splattering everywhere from excessive pressure.

For rinsing fiberglass go with the green nozzle. It provides for a more powerful spray. The nozzle orifice is smaller, which focuses the water into a more concentrated stream. With a 25 degree spray pattern, the green nozzle is able to more forcefully lift dirt and grime with increased water pressure.

If this is your first time and you’re unsure or reluctant about cleaning with different levels of pressurized water, start slow test the water pressure with every nozzle you plan to use. Work in baby steps and go with what you’re comfortable with. Scared of what the green nozzle might do to your fiberglass? You can always go down a notch and work with the white nozzle, which has a 40 degree spray pattern and uses less water pressure.

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Consider using pressure washer attachments

Pressure washers have different attachments in addition to different nozzles. If you plan on using soap or a cleaning solution to aid in cleaning your fiberglass, you’ll want to make sure to get a soap attachment for your pressure washer so the cleaning solution is used effectively.

Make sure to only get cleaning solutions that are usable with your pressure washer so that no damage is done to your pressure washer. 

You can also get a brush attachment for your pressure washer to help get rid of built up stains.

Step two: Prep and start your pressure washer

Two obvious things you’ll need to do first. If you’re using an electric pressure washer you’ll need to find an outlet to plug the unit into. Make sure you have enough line and slack to complete the washing. You’ll also need a water source. If you’re at home then connect a garden hose from an outdoor spigot to the washer and turn on.

Next, if you’re using a cleaning solution, prepare for that. Some washers have an on-board detergent/soap tank that you can pour into. If the cleaning solution is a concentrate, mix the proper water and concentrate solution before pouring. For those washers that don’t have a built-in soap tank, you’ll have to use a siphon hose.

Connect the black nozzle to the washer wand. Most wands have a quick click design that has a collar. The collar is pulled down when connecting a nozzle tip to it.

Step three: Position yourself 3 to 4 feet away from the surface

You always want to give yourself a good distance from the surface you’re cleaning. Start with a clearance of 3 to 4 feet. This will not only protect the surface that you’re cleaning, but also yourself from whatever recoil that the pressurized water might that might come out from the spray.

A good idea is to do a test spray on a small patch of fiberglass. Do it with whatever nozzle you’re working with, just to make sure you’re not working with too much pressurized water. After you’ve found what you’re comfortable with, adjust your position as needed.

Step four: Pressure wash with cleaning solution using the black nozzle

Pull the trigger on the spray wand and wash. There’s isn’t any one proven technique to pressure washing fiberglass. However, most people spray with horizontal sweeps, starting from the bottom and working to the top. Some say this helps prevent streaking from dirty soapy water that can flow down if working from the top towards the bottom.

After the cleaning solution has been sprayed on, give it 10 minutes for the magic to happen. Dirt and stains will be loosened up and ready to be rinsed off.

Step five: Pressure wash to rinse off cleaning solution using green nozzle

Switch to the green nozzle and rinse off the cleaning solution. You’ll use the same method and technique that you used when you washed. Spend a little extra time on stubborn stains. Let the pressurized water lift and blast away whatever is sticking to the fiberglass surface.

Tips for Using Pressure Washers Safely

Tips for Using Pressure Washers Safely

When using pressure washers, it’s extremely important to use them safely and with caution. Follow these tips for safely using a pressure washer for any use:

  • Wear safety glasses when operating a pressure washer.
  • Wear a mask when operating a pressure washer if around hazardous materials that could blow back, like paint, dirt, dust, mold and mildew.
  • Always use the safety lock on the sprayer’s trigger when changing nozzle tips or when not actually using the pressure washer.
  • Always stand 3 to 4 feet away from any surface being pressure washed.
  • Never put your hands or other body parts in front of the spray of a pressure washer. 
  • Never point a pressure washer’s nozzle at anyone else, pets, other objects, or anything else not being pressure washed – even when it’s not in use.
  • Never use a pressure washer while on a ladder or other tall or rickety surface. Recoil from the pressure washer could cause you to fall and be injured. 

Basics of Pressure Washing and Fiberglass

Basics of Pressure Washing and Fiberglass

If this is all new to you, let me go over some basics of what pressure washing and fiberglass are. Hopefully, that’ll give you a better understanding of what we’re talking about and a better picture of what you’ll be doing.

What is pressure washing?

At its core, pressure washing is the use of a pressurized water spray to remove things like dirt, grime, old paint, mud and mold from surfaces like buildings, vehicles, and in our this case, fiberglass.

It does this with the use of a motor and a pump, which work together to accelerate water to very high pressures. The water pressure coming out is managed to a degree by the nozzle used. Different combinations of pressurized water and spray pattern are used to clean specific surfaces.

While there’s a lot of different kinds of pressure washers on the market, in general, they’re grouped into two categories: electric powered and gas powered. Besides the type of motor that’s used, these two washers are differentiated by how much power and water pressure they’re able to produce.

Electric pressure washers are generally utilized for smaller projects. They’re great for cleaning cars, boats, grills, and other smaller items that don’t need a ton of pressure to be cleaned. Electric pressure washers use less force and are therefore generally less powerful than gas power washers; they emit anywhere from 1,300 to 1,700 pressure per square inch (psi) of water. 

On the other hand, gas pressure washers are generally utilized for bigger projects, like pressure washing fences, patios, sidewalks, driveways, decks, and other large surfaces. They emit 2,000 to 3,000 psi, meaning they pack a bigger punch than electric pressure washers.

What is fiberglass?

It’s likely that you’ve come in contact with something that’s fiberglass every day without even knowing it – it’s a very common and versatile product. Fiberglass is a form of plastic that is reinforced with glass fiber. It’s lightweight, strong, and able to be molded into various shapes; that’s one of the big reasons why it’s used so widely.

Fiberglass is used in different ways and across multiple industries. To give you some perspective, you’ll find fiberglass used in the following industries:

ReadyToDIY is the owner of this article. This post was published on September 10, 2019.

  • The home industry
  • The automotive industry
  • The beverage industry
  • The food processing industry
  • The chemical industry
  • The docks and marinas industry
  • The paper and pulp industry
  • The aquariums and fountains industry

And that’s not even all of them! In our everyday lives, fiberglass is found in cars, RVs and motorhomes, bathtubs, roofs, boats, aircraft, and aquariums.