How to Make a Fiberglass Bathtub

Do you want to make your own fiberglass bathtub? You might not know what you need for this project, but don’t worry! This blog post will show the necessary steps in how to make a fiberglass bathtub. The materials are inexpensive, and it is an easy process that anyone can do at home.

How to Make a Fiberglass Bathtub

Fiberglass is a composite material made of woven glass fibers. It has been used in the construction industry for decades, and it can be formed into just about any shape. So stop reading this paragraph and get started on making your next DIY project happen!

Required Tools and Materials

  1. Respirator
  2. Safety Glasses
  3. Wet Sandpaper (220 grit)
  4. Fiberglass Cloth (choose a weave that is suitable for your project)
  5. Polyester Resin (regular or high performance)
  6. Catalytic Hardener (for high-performance resin only)
  7. Mixing Cups
  8. Stir Sticks
  9. Plastic Gloves
  10. Bucket

A Detailed Guide How to Make a Fiberglass Bathtub

A fiberglass bathtub is a great option if you’re looking for a durable and affordable tub. Fiberglass is a rigid, weather-resistant material that will last for many years with proper care. Here’s how to make your own fiberglass bathtub:

Step 1: Measure Dimension

The first step in How to Make a Fiberglass Bathtub is to measure the dimensions of your bathtub. This will help you determine how much fiberglass resin and cloth you’ll need. How big of a fiberglass “blanket” depends on factors, including the density of the weave, but generally, 1 yard can cover about 30 square feet.

Measure the Bathtub Dimension

Step 2: Prepare Your Work Area

Making a Fiberglass Bathtub project requires the right work environment for the process to go smoothly. It would help if you kept your floor or table free of debris that could get into the fiberglass resin; anything small enough will be embedded into the finished product, and any larger pieces can scratch or damage it when you’re working. Cover your workspace with newspaper. Protect your eyes with safety glasses, and cover your mouth with a respirator or dust mask. How to Make a Fiberglass Bathtub also recommends protecting yourself further by wearing gloves during this project.

Step 3: Mix the Resin

The resin you use for Making a Fiberglass Bathtub should be catalyzed with a hardener. Follow the manufacturer’s instructions for how to mix the two products. Be sure to measure accurately, as improper mixing can cause problems with the finished product.

Step 4: Wet the Surface

Before you apply the fiberglass resin, you need to wet the surface of your bathtub. You can do this by using a spray bottle filled with water or using a paintbrush to wet the surface. This will help the resin adhere to the tub. Fiberglass Bathtub recommends wetting about 1 square foot at a time and using a wire brush to remove any dirt or debris that might interfere with the resin adhesion.

Wet the Bathtub Surface

Step 5: Apply Resin

Apply the mixed resin onto wetted surfaces. Use a paintbrush for this step because it applies even pressure across the entire surface, making square edges easy. How often you add fiberglass cloth is determined by how thick your finished product is.  Add one layer at a time until the desired thickness is achieved, allowing each layer of fiberglass cloth to dry before adding another layer.

Step 6: Lay the Cloth

Once the resin has had a chance to harden (which should only take a few minutes), lay the fiberglass cloth over it. Again, be sure to work quickly, as the resin will continue to harden. Making a Fiberglass Bathtub recommends using weights or clamps to keep the cloth in place while it dries. How long to let it dry will vary depending on your project and conditions, but generally, a Fiberglass Bathtub recommends letting the resin begin to harden before moving on to the next step.

Step 7: Repeat

Apply another layer of resin over the first layer of fiberglass cloth and let it dry. Next, wet the surface, apply the resin, and add another layer of material. Let it all dry before sanding. Fiberglass Bathtub recommends using 220-grit sandpaper for the best results.

Step 8: Apply Sealant

A fiberglass bathtub is not waterproof, so you’ll need to apply a sealant to protect it from moisture. Using polyurethane sealant is recommended for making Make a Fiberglass Bathtub. Follow the manufacturer’s instructions for application.

Step 8: Finish the Surface

Once the resin has fully cured, you can sand down the surface to achieve a smooth finish. Be sure to use wet sandpaper (220 grit), and work in a circular motion. For a Fiberglass Bathtub, using a bucket of water to keep the sandpaper wet is recommended. Finally, apply a coat of automotive clear coat to protect your new fiberglass bathtub from scratches and fading. Use paint sprayers or an airbrush to apply a clear coat.

Using Sandpaper on Bathtub

Tips and Warnings


  1. Tape off the areas you don’t want fiberglass to go, such as the floor and countertop.
  2. Apply a layer of fiberglass cloth to the surface and then soak it in resin.
  3. Wait for the resin to dry and apply a second layer.
  4. Let the fiberglass bathtub dry entirely before using it.


Be very careful when working with fiberglass. It is a sensitive material and can easily cut your skin. Always wear gloves and safety glasses when working with it. If you get cut, rinse the wound with soap and water and apply hydrogen peroxide. Seek medical attention if the cut is severe. Working with fiberglass can be a messy job. Have a wet towel on hand to clean up any spills.

You Can Check It Out to Get Suction Cups to Stick to Bathtub

How Many Layers of Fiberglass Do I Need for a Tub?

To ensure that the tub is sturdy and durable, you should add a few more layers of fiberglass than you think is necessary. This gives it a “built-in” strength that will help to prevent cracking when the tub is filled with water.

How many layers you need really depends on what kind of fiberglass resin you use (regular or extra-thick), the size of your mold (larger sizes require greater thicknesses), and how much weight you plan to put into your finished tub. For average-sized bathtubs, figure on four to five layers of fiberglass cloth.

How Can I Use a Fiberglass Bathtub Without It Cracking?

As a general rule, a fiberglass bathtub can last up to 50 years if properly taken care of and well-maintained. How long your tub will really last depends on several things: how it was originally made, the quality of the materials used, whether it has been damaged over time, where you live, and who uses the tub.

Fiberglass Bathtub Can Last Many Year

Porous areas like whirlpools or jets that have been worn down from use will start to allow water into the fiberglass, which can cause cracking later on—to prevent this from happening, make sure you check these areas regularly for wear and replace them as needed.


Following the steps on how to make a fiberglass bathtub, With the right tools and materials, you can make your fiberglass bathtub in no time. If this sounds like something you want to try, let us know! We’re happy to help answer any questions or provide detailed instructions on how to get started. You may also be interested in reading our other blog posts about DIY projects for a bathroom remodel. Thanks for reading – we hope it helps!

You can also check it out: How to Make Bathtub Non Slippery

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