Best Hot Tub Shell Techniques Explained

When it comes to hot tub manufacturing not all shells are created equal. There are several methods used in making hot tub shells, each with its own advantages and considerations. Here are some of the commonly employed methods:

  1. Vacuum Formed Shell: Vacuum forming involves heating a sheet of acrylic or ABS (acrylonitrile butadiene styrene) plastic and placing it over a mold. The air is then evacuated (sucked) from between the sheet and the mold, causing the sheet to form to the shape of the mold. Once cooled, the shell is trimmed and reinforced. In the case of vacuum forming an acrylic sheet (not ABS), the acrylic is reinforced by spraying several layers of fiberglass for superior strength and durability. Vacuum formed shells offer a smooth and glossy finish and can be cost-effective for certain designs.
  2. Acrylic/Fiberglass Shell: This is a popular method where a mold is used to create the hot tub shell. Layers of fiberglass are applied to the mold, followed by the application of colored acrylic or gel coat. This combination creates a durable, non-porous, and glossy finish. Acrylic/fiberglass shells are known for their resistance to cracking, fading, and staining. They are also the strongest and heaviest shells in the industry.
  3. Thermoformed Shell: Similar to vacuum forming, thermoforming also utilizes heat and vacuum to shape a sheet of material over a mold. However, thermoforming typically involves thicker sheets and a combination of vacuum and pressure to achieve more intricate designs. Thermoformed shells can offer greater structural integrity and design flexibility compared to vacuum-formed shells.
  4. Rotationally Molded Shell (Roto-Mold): In this method, a specialized mold is filled with a powdered polymer material, typically polyethylene. The mold is then rotated bi-axially while heated, causing the material to evenly distribute and adhere to the mold’s surface. Once cooled, the shell is removed, trimmed, and finished. Rotationally molded shells are known for their durability, impact resistance, and ease of maintenance.

Although we feel that methods #1 and #2 above are the best practices, it’s important to note that the “best” method for manufacturing a hot tub shell can depend on various factors, including the desired aesthetics, durability, cost, and manufacturing capabilities. Different manufacturers may employ different methods based on their specific requirements, preferences, and in some cases limitations (fiberglass permits are harder to get). Ultimately, it’s recommended to research and consult with hot tub manufacturers to understand the manufacturing methods they employ and how they align with your specific needs and preferences.

For more information on how to research and compare party hot tubs before purchasing please visit our hot tub buyer’s guide pages. You can also click on the pink boxes at the top right of every page to get a free local quotes from dealers in your area. Or click our “Spa Buyer’s Consult” link above to get one on one expert advice on the best hot tubs available in your area.

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