Finally, beginning in the late 1970’s, cross-linked continuous cast acrylic sheet was recognized as a superior product for manufacturing spas. Its resistance to chemicals and sunlight combined with the ability to vacuum form it into complex shapes made it the ideal product for this application. Due to the low barrier to entry into this market, over the next twenty years the industry grew to at least 100 manufacturers in North America. Eventually the demand for spas spread throughout the world. Europe, Australia, and Asia (China) have become significant participants in the industry as manufacturers and consumers. The high investment requirements to produce a product to meet the needs of spa manufacture result in a limited number of sheet manufacturers.
There are only three manufacturers in the world that can provide the special acrylic sheet. They are Aristech Acrylics (Kentucky), Mitsubishi Rayon Company (MRC/Japan), and Lucite®(Tennessee), which was purchased by MRC in 2009. Lucite® was originally owned by the DuPont Co., but has been sold three times since 1990. The properties of their sheet are very similar, but their colors and textures are not identical even though they may have the same name. The best spa repair requires the knowledge of the original sheet manufacturer in order to achieve the best duplication of color. Acrylic sheet used for spa construction is normally reinforced with glass-reinforced polyester resin. However, some manufacturers use a composite sheet made by extruding ABS on the back of the acrylic sheet. This improves the impact performance and reduces the VOC’s of their process.
Since the beginning of continuous cast sheet in this market, the manufacturers have created many different colors, effects, and textures. The first spas were a solid color. Soon, the manufacturers learned to make attractive colors, called marble, by using two colors that were poorly mixed.
This capability soon grew to the use of three colors, which added more depth to the surface. Generally, these products were produced using white, black, and a third color.
The next development was to create “granite” surfaces to build on the growing popularity of using granite and solid surface products for kitchen countertops. These granite products are produced by mixing small or large particles (chopped up) of colored acrylic sheet or blocks into a matrix of colored or clear acrylic sheet.
The next development was to create pearlescent colors. Although, the first products were a solid color, it quickly grew to using them in combination to recreate the “marble” look. Unfortunately, it was later discovered that the ingredients used for these very unique colors increased the potential for stress cracking in spa service.
Finally, the latest new look are referred to as mineral or Lustre products. They are characterized with a surface that has some texture but are basically a one color sheet. Typical surface issues in these spas are stress cracking caused by chemical attack or expansion/contraction (accelerated by sunlight), blisters, delamination, impact damage, and occasionally color fading from chemical attack. All of these defects can be repaired using our MMA, Granite, or Quick Glaze systems. Refer to the Product Color section to select the correct color, effect, or texture. The Acrylic Filler should always be used when repairing a spa. It is then color coated and sealed with the K2000 clear topcoat. Please refer to the Granite procedure, MMA procedure, or Quick Glaze procedure for more details in choosing the correct system. Many spas are produced using a base constructed of ABS, which can get damaged during handling. These bases can be repaired using our ABS pan Repair Kit. Also, if the surface has so much damage that it is not practical to repair, the entire surface can be renewed using our FRL system and creating a new white surface.