What is Thermobond™ Spa Shell Construction in Vortex Spas™?

If you've been considering Vortex Spas, you may have encountered the term Thermobond™ Spa Shell. This article explains what aThermobond™ Spa Shell is and how it’s made.

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When shopping for a spa, one of the most important features to consider is the spa shell because you can replace pumps, heaters and other parts, but not the spa shell.

Vortex Spas™ uses the durable Thermobond™ Spa Shell, which is designed to last the lifetime of your spa.

In this article, you'll learn:

What is a spa shell?

A spa shell refers to the main structure or body of a spa that holds the water, seats, and jets and is typically made of durable materials such as acrylic, vinyl, or plastic.

spa shell

The spa shell acts as a barrier between the water and the surrounding environment, ensuring that the water remains contained in the spa and provides the foundation for the overall spa experience.

The spa shell's construction and quality are important factors to consider when purchasing a spa pool as they impact its strength, durability, safety, and overall aesthetic appeal.

One of the ways spa manufacturers remove cost and result in super low retail is to use sub-standard acrylic and other shell components, such as resins. Always check that the shell warranty is not longer than the company has been in business and make sure it is not a Pro rata warranty, meaning the value of the warranty degrades over time.

Investing in a spa shell with superior construction ensures durability, effectively preventing cracks, leaks, and damage. This high-quality construction extends the lifespan of your spa, allowing you to enjoy it for years to come.

What is an Acrylic Spa shell?

An acrylic spa shell is constructed using a single sheet of acrylic that undergoes a heating process and is then placed over a specially designed mould. The acrylic sheet is carefully shaped and formed to fit the desired spa design.

Thermobond Spa Shell

Once cooled, it retains its moulded shape, resulting in a durable and seamless shell for the spa. The finished acrylic shell has a glossy and smooth surface, enhancing its visual appeal and providing a comfortable touch for users.

Renowned spa brands like Jacuzzi® Spas, Vortex Spas™, Fisher Spas™, HotSpring® Spas, Master® Spas, and Alpine Spas™ use acrylic spa shells.

What is the Thermobond™ Spa Shell Construction?

The Thermobond™ Shells used in Vortex Spas™ are made with high-quality materials and processes to ensure strength and durability. They feature the superior USA-made Aristech™ acrylic. The Thermobond™ Spa Shell is produced using an 8-step, 4-layer process that is second to none.

How Vortex™ Spa shells are made?

How is the Thermobond™ Spa Shell made?

The production of the Thermobond™ Spa Shell is a careful and detailed process. Each step is done with precision and attention to detail. In this section, we will walk you through each stage, giving you an easy-to-understand overview of how the Thermobond™ Spa Shell is made.

Step 1: Acrylic Preparation and Sanding

American-made Aristech acrylic is kept in a climate-controlled environment to avoid moisture penetrating the acrylic surface, as is the resin and fibreglass used in the shell construction. When required, the acrylic sheet is hand-sanded to assist adhesion to the fibreglass layers.

Step 2: Acrylic Heating and Vacuum Forming

The acrylic sheet is heated in a zone-controlled oven before being vacuum-formed into the spa mould. The zone-controlled heating ensures the thickest possible acrylic shell is formed. This method of zone heating is only used by premium spa manufacturers, as it is the most precise method of acrylic forming available.

Step 3: Application of Vinyl Ester Resin

The formed acrylic shell is then sprayed with pure vinyl ester resin. Vinyl ester resin is the industry’s best quality resin. It is also the most expensive resin and therefore, many manufacturers do not use it. This resin gives the acrylic a permanent water seal to eliminate the chances of delamination. It also provides a base for the following layer to adhere to.

Step 4: Curing Process in a Controlled Environment

The shell enters a temperature and humidity-controlled curing oven. This process is crucial for resin and fibreglass manufacturing as it ensures that any moisture in the resin or shell evaporates and allows the resin to cure evenly over the shell, creating a permanent water seal.

Step 5: Application of Polyester Resin and Fiberglass Layer

The shell is sprayed with its 2nd & 3rd layers – marine grade, pure polyester resin and glass fibre. This layer bonds with the vinyl ester and acrylic shell to ensure permanent adhesion. It also reinforces the shell, along with the following layers.

Step 6: Additional Curing Process

The spa re-enters the curing oven for a second pass to cure the polyester resin and fibreglass glass.

Step 7: Ensuring Durability

The lip of the spa and crucial weak points are strengthened using hand-layered fibreglass sheets. At this point, timber blocks are fibreglassed onto the spas shell to provide fixing points for the frame and equipment.

Step 8: Application of GP Resin and Stone Powder

The shell's 4th layer is sprayed using GP resin mixed with stone powder. This layer sets like concrete to give unsurpassed shell strength. The torsional rigidity that the stone powder gives the resin, means that our spas do not have to use timber supports under stress areas that many spas rely on.

Thermobond™ vs Rotomould vs Vinyl Spa Shells

Acrylic, Rotomould plastic, and Vinyl are commonly used materials to make spa shells, but they have some differences:

Thermobond™ (Acrylic) Spa Shells

Acrylic is a durable and popular material used in spa shells. It is known for its glossy, smooth finish and its excellent resistance to UV rays and chemicals.

Acrylic spa shells are usually vacuum-formed and reinforced with fibreglass or other materials for added strength. These shells are available in various colours and designs and are considered to be the highest quality option.

Rotomould Plastic Spa Shells

Rotomould plastic, also known as rotationally moulded plastic, is a type of plastic that is melted and rotated inside a mould to create the desired shape.

These spa shells are generally less expensive than acrylic shells. However, they may not have the same level of aesthetic appeal or smoothness as acrylic shells. Rotomould plastic shells are typically lighter in weight but still durable and resistant to impact or cracking.

Vinyl Spa Shells

Vinyl spa shells consist of a vinyl liner that is stretched and fitted over a frame or structure. These shells are usually the least expensive option, making them a popular choice for budget-conscious buyers.

Vinyl shells are lightweight and easy to install but may not have the same durability or lifespan as acrylic or rotomoulded plastic shells. They can be prone to tearing or puncturing, but repairs can be made by replacing the damaged vinyl liner.

Learn more about acrylic and rotomould spa shells in our detailed comparison article below.

Pros and cons of Thermobond™ Spa Shell

Just like any other spa shell material, acrylic or Thermobond™ Spa Shell has advantages and disadvantages. Let’s take a look at its pros and cons below.

Pros of Thermobond™ Spa Shell

  • Highly durable
  • With proper insulation, it retains heat very well
  • Has a sleek and glossy finish, creating a sophisticated and high-end aesthetic appeal.

Cons of Thermobond™ Spa Shell

  • Thermobond™ spa shells may be heavier than other materials due to their specific composition, making them more difficult to move around.
  • Thermobond™ spa shells need proper insulation to effectively retain heat. Without sufficient insulation, they are equally energy-efficient as other spa shells with similar insulation levels.
  • Thermobond™ spa shells, including most acrylic spa shells, tend to cost more than other shell materials like plastic rotomould.

In Summary

Thermobond™ shells are constructed from premium materials to ensure their strength and durability.

The Thermobond™ shell is carefully constructed using an 8-step, 4-layer process, ensuring that it is built to last the entire lifespan of your spa.

Got questions? We are here to help! If you are interested in a spa pool with a Thermobond™ shell you can chat with one of our consultants to learn more.

Please click the chat button at the bottom of this page or click the button below to contact us.

DISCLAIMER: In this article, we’ve used brand names not affiliated with Spa World™ or Vortex Leisure Pty Ltd, the parent company of Spa World™.

Affiliations: Vortex® Spas, Fisher™ Spas and Spa World® are trademarks owned by Vortex Leisure Pty Ltd. The Jacuzzi® brand is owned by Jacuzzi Inc. and exclusively licensed for use to Spa World™ in Australia and New Zealand.

The following registered trademarks are owned by companies not affiliated in any way with Spa World™ or Vortex Leisure Pty Ltd: Alpine Spas™ trademark is owned by Alpine Spas Limited. Master Spas® trademark is owned by Master Spas®. HotSpring® Spas trademark is owned by Watkins Manufacturing Corporation (Watkins).

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