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Everything you need to know about Fiberglass pool

What is a Fiberglass pool and how is it made?

A fiberglass pool is one of the most popular options for homeowners who want a pool in their backyard. Fiberglass pools are durable, long-lasting, and don't require much maintenance. They're also affordable, which means you get the best of both worlds: a great pool that you'll enjoy for years to come, but won't break your budget.

A fiberglass pool is a fantastically durable, beautiful addition to any backyard. But what exactly is a fiberglass pool?


They're a great investment for your home. Not only are they low maintenance, but they're made of a material that's virtually indestructible and resistant to rust, mold, and mildew. They can be installed in just 1-2 days and can be used all year round, with little to no additional work apart from regular maintenance.

The Manufacturing Process

Fiberglass pools are made from a combination of resin and fiberglass. The manufacturing process is similar to that of concrete or vinyl pools, except that resin is used instead of cement and water.

Fiberglass pools are made in the following steps –

  1. The Pattern
  2. The Mold
  3. The Gel Coat
  4. Vinyl Ester Resin Layer
  5. Fiberglass: Chopped Strand Mat – 1st Coat
  6. Fiberglass: Chopped Strand Mat – 2nd Coat
  7. Woven Roving Fiberglass Layer
  8. Fiberglass: Chopped Strand Mat – 3rd Coat
  9. Honeycomb Core
  10. Fiberglass: Chopped Strand Mat – 4th Coat
  11. Fiberglass: Chopped Strand Mat – 5th Coat
  1. The Pattern

This process begins with the production of the pattern - the original shape of the pool shell. It is made of wood, fiberglass, putty, and primer.

It is not a pool, but a replica of the pool. From this, the mold is then created. The mold is built inside the pattern and then removed. Once the pattern is complete, liquid sealants and release agents are applied to the model so that the finished mold can be removed. The production of the pattern takes about 1-2 months.

2. The Mold

The mold is the second step in designing a new fiberglass pool.

3. The Gel Coat

Fiberglass pools are made from the inside out! The Gelcoat is the color you have chosen for your pool. The Gelcoat is a colored resin that is applied to the mold with a spray gun. This Gelcoat is applied in three separate coats to achieve a strong gel finish (up to 30 mils). If this step is not done properly, the gel coat may be too thin, causing bubbles to form on the surface of your pool. On the other hand, if the layer is too thick, the first layer of your pool's surface may crack.

Most fiberglass manufacturers use polymerization to ensure durability. In simple terms, joining two or more of these components by a crosslinking process to achieve strength and durability). They also use other equipment to ensure proper humidity and air quality.

4. Vinyl Ester Resin Layer

After the Gelcoat has cured, the next step is to spray on the vinyl ester resin barrier coating (water barrier). The Gelcoat is semi-permeable, meaning that certain water molecules can pass through the outer layer of the Gelcoat. If the underlying layer is polyester, a reaction can occur that causes blistering or corrosion. For this reason, a layer of the vinyl ester is placed under the Gelcoat. Ensure your builder uses a manufacturer that incorporates this layer into their fiberglass.

5. Fiberglass: Chopped Strand Mat – 1st Coat

Chopped Strand Mat (CSM) is a random fiber mat that has the same strength in all directions and is used in a variety of hand laminate and open mold applications. In the manufacture of chopped fiber mats, continuous fibers are cut into short lengths of 1.5 to 3 inches and the cut fibers are randomly distributed across a moving belt to form a "web" of random fiber mats. A binder is applied to hold the fibers together, and the mat is cut and rolled.

Because of their random fiber orientation, chopped strand mats are easily conformed to complex shapes when wetted with polyester or vinyl ester resins. After the layer of chopped fiberglass is applied, it is rolled using rollers to avoid air bubbles. This layer must then be cured.

6. Fiberglass: Chopped Strand Mat – 2nd Coat

A second layer of the chopped strand fiberglass is applied after the first fiberglass layer is cured. This will add an additional layer of strength and durability to the first layer. Once the second layer is in place, it is similar to the first layer, rolled to prevent air bubbles and then left to cure.

7. Woven Roving Fiberglass Layer

Apply a layer of woven roving layer of fiberglass. Some manufacturers replace this step with an additional layer of chopped fiberglass. It is important to make sure that the layer is thick exactly where it needs to be thick (only in certain places like corners and where the pool wall meets the pool floor). If the fiberglass is too thin in certain places, it will create "thin spots" that can cause cracks in the Gelcoat. For this reason, a layer of woven roving is applied in this step so that this layer is uniform and free of uneven areas.

8. Fiberglass: Chopped Strand Mat – 3rd Coat

The third layer of chopped fiberglass is applied. After application, it is rolled to prevent air bubbles and then left to cure. This adds another layer of strength and durability to the first and second layers.

9. Honeycomb Core

Vertical strips of honeycomb core are inserted along the fiberglass walls of the pool. They are installed to provide structural integrity to the fiberglass pool walls by adding strength to the fiberglass fabric itself. Without this step, the fiberglass fabric is more flexible and susceptible to hydrostatic pressure.

10. Fiberglass: Chopped Strand Mat – 4th Coat & 5th Coat

The fourth & final (fifth) layers of Chopped strand fiberglass mat are applied at this point and then rolled to avoid bubble formations to complete the formation of the pool shell. These final layers much like the previous layers further add to the strength of the structure.

From what is seen above, the manufacturing process of a fiberglass pool structure is rather complex, hence as simple as it looks, like a tub, it isn’t quite like it.

So, when you are in the market to figure out which pool to choose, which structure is most dependable and most durable and strong, you would be remiss to not give fiberglass pools a thorough consideration.

After all, you and your family deserve only the best!

How do you fix spots, stains, and blisters in fiberglass pools?

We all know the problem of pool stains. Fiberglass pools are generally low maintenance, but eventually, something will get into your pool that doesn't belong there. Whether it's a bag of charcoal you forgot or grass clippings from your neighbor's lawn, unwanted debris can cause black spots and stains in your pool. Luckily, these problems aren't hard to fix! Here's how you can remove them:

Fiberglass pools are, generally speaking, low-maintenance.

They're easy to maintain and clean. It's also easier to repair them if there's a problem; in most cases, you can even do it yourself. But there's a catch: fiberglass pools are more prone to discoloration and damage than other pools.

However, all pool owners experience issues with their pools from time to time.

Fiberglass pools are low maintenance and easy to care for, but they aren't perfect. Occasionally, you'll find yourself scratching your head when you notice a problem with your fiberglass pool. Here are some things that can go wrong:

  • Black spots on the surface of the water
  • Stains on the bottom and sides of the pool
  • Blistering or bubbling of paint

And when you have a blemish or stain on the surface of your fiberglass pool, it can be frustrating not knowing what caused it or how to remove it.

But don't worry, we're here to help! We've compiled a list of the most common stain culprits and show you how to get rid of them for good:

  • Soiling caused by debris (e.g., leaves, sand) can be removed with a leaf rake or leaf vacuum cleaner and then brushed with an anti-stain gel.
  • Black spots are caused by mold stains that appear during the winter months when no chlorine protects the surface from mold growth; scrubbing with bleach kills any remaining mold spores so they don't return the next year.!

Here are a few common issues and ways to fix them.

In the world of fiberglass pools, nothing is more common than black spots. Black spots can occur for a variety of reasons, including:

  • An above-average concentration of sunlight on the surface of the basin (especially in southern climates)
  • Surface dirt that has accumulated on the pool water or around jets/filters/electrical equipment and has not been removed by vacuuming or skimming. If this happens often enough, it can cause these areas to heat up and displace dyes into other areas of your pool. This is especially true if you do not use a weekly shock treatment (chlorine).

Black Spots: These can be caused by anything from the high iron content in your water to have left a bag of charcoal in the pool overnight.

The easiest way to remove these stains is with a pumice stone (for softer stains) or an orbital sander (for harder stains). If your fiberglass pool has been stained by black algae, you should start with the pumice stone. Scrub the stain until it's gone, then rinse your pool thoroughly. If there are still some stubborn stains left, use an orbital sander with 120-grit sandpaper instead of 220-grit sandpaper - that way you won't scratch the fiberglass walls too much while you're trying to remove those pesky bubbles.!

Stains: Stains are usually caused by various elements entering the pool's water like grass clippings, leaves, and dirt.

If a stain is caused by the high iron content in your water, you can easily remove it with a simple pool cleaner like WaterCo's Trident Vacuum Cleaner. If you're not sure what caused the stain and want to be sure it won't come back, you need to test your water for various metals and minerals.

If you have hard water spots or stains on your fiberglass swimming pool's sides, it could be due to several factors including:

  • leaving a bag of charcoal in the pool overnight
  • not scrubbing algae off of steps regularly (or at all)

In some cases, they may even be caused by bacteria. If removed in time, they're usually easily removed with a stain remover.

If the stain is still fresh and hasn't had time to bond with the surface of your pool, you may be able to remove it with a chlorine-free bleach. You can get these at your local pool supply store.

Make sure the products you use are safe for fiberglass surfaces before you use them. Some chemicals can damage fiberglass. Follow the instructions on the container carefully - it's important to get the timing right.!

Blistering and bubbling: Both blistering and bubbling are signs that there's something wrong with your pool's gel coat.

Blistering, which is more common than bubbling, looks like small bubbles or blisters on the surface of the pool. Bubbling, which is less common than blistering but can be even more damaging to your fiberglass pool, causes larger holes in the gel coat.

It's not always clear what causes these problems on the walls or deck of a fiberglass pool, but it could be related to improper installation or cleaning techniques (or both). To find out if you have a problem with your fiberglass coating, look for patches of discoloration that differ from their surroundings - if so, they may be areas where the coating has been completely removed and replaced with fresh resin.

Indoor pools may have blistering if humidity levels aren't sufficiently controlled during the construction process.

If you've ever seen a fiberglass pool and thought it looked like a giant bubble, you've your finger on the pulse of these things. Bubbling is caused by not controlling the humidity during construction. Indoor pools can have this problem if the humidity isn't adequately controlled during construction, but outdoor pools don't have this problem unless they're located in an area where rainwater frequently pours over them.


If your fiberglass pool is cracking, blistered, and bubbling like a bubble bath on steroids, there is no need to worry. It simply means that the gel coat needs to be repaired by replacing it with new layers of resin-soaked fiberglass fabric over the damaged area.

Overall, the regular maintenance of your fiberglass swimming pool structures is of considerable import if you are to enjoy a problem-free time with your loved ones in your new or already installed fiberglass swimming structure.

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