Manufacturers that use OAS as the shell surface material usually use a thick layer of solid foam for its structural support. This hardened, rigid foam works just like fiberglass and provides a structurally sound support system needed for your spa. However, this thick layer of foam necessitates covering the plumbing lines and fixtures of the spa, which can make servicing more difficult. The majority of manufacturers that use acrylic as the shell surface material utilize a combination of fiberglass and additives for its understructure. The thickness is a key factor in determining the spa s structural integrity and longevity.
Manufacturers can save hundreds of dollars by using only a thin layer of fiberglass.
In order to verify that the spa you are purchasing has a thick layer of fiberglass, you may want to ask your retailer to see a cross section of the spa shell. The quality of the manufacturing process relates to the application of the fiberglass to the acrylic shell. Look for manufacturers that hand roll each layer of fiberglass to the acrylic shell. Although this process is expensive and labor intensive, it is the only way to prevent deterioration and delamination of the acrylic shell. This results in blisters, cracks, and bubbles in the shell.