Using thermoplastic finishes on new pool installs and renovation projects

by Sally Bouorm | March 1, 2015 12:05 pm

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By Brian Burton

Those in the Canadian pool industry know how seasonal climate change can affect an inground pool surface. It is one reason why many pool owners turn to specialists when they are finally able to see what lies beneath their cover when they open their pool in the spring.

There are several pool repair/replacement options available for failed and/or failing pool surfaces, which range from paint, plaster, and vinyl liners to fibreglass and aggregates. A more recent option is high performance thermoplastic pool finishes.

In the past, pools were coated with rubber-based paints; however, in the late ’80s, regulations banned many of the key ingredients in these products, which reduced their performance. This led many pool designers and builders to switch to plaster and other types of finishes.

Plaster (marcite), in its own right, requires a long and complicated start-up process and is prone to staining, shrinking, and cracking. When plaster—a mix of Portland cement and sand—is applied to a pool shell, it requires a cure time of at least two to four weeks. After the pool is filled with water, calcium (Ca) leaching occurs and various chemicals are required to balance the water’s pH level. This adds to the time the homeowner must wait before they can enjoy their pool. For climate-challenged Canadians, this can shorten an already abbreviated pool season.

Some reports have found plaster deterioration to be caused by calcium hydroxide Ca(OH)₂ leaching from localized areas of pool plaster, while acidic pool water can wreak havoc on plaster finishes and pool plumbing, resulting in etching and staining.

Proposed solutions to control pool surface damage caused by aggressive water include: paying careful attention to water chemistry to avoid unbalanced water conditions, or providing a chemically inert barrier, such as a thermoplastic finish, between the pool water and the marcite surface.

Thermoplastic finishes are designed for new pool surfaces or resurfacing of concrete (plaster [marcite], and Marbelite), fibreglass, steel substrate; aluminium; composite pool panels; and hybrid pools, which comprise a combination of different substrates.

Pool finish advancements

As technology advances, more options other than traditional pool surface repair methods become available. For instance, thermoplastic-spray systems incorporate multiplex powders comprising modified acrylic resins designed to obtain a smooth coating. The finish flows wet and bonds easily to form smooth and continuous cured films. These films become permanent pool and/or hot tub liners for new construction projects and can also be used to renovate existing indoor/outdoor commercial or residential pools and hot tubs. Thermoplastic finishes are gaining popularity as they are designed to be fade-, stain-, blister-, and peel-resistant and can be installed quicker than most traditional pool finishes.

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Thermoplastic pool finishes are applied pneumatically—air and propane operate the mobile spray system. The small thermoplastic powder beads are propelled through a patented applicator, melting and liquefying as they pass through the nozzle, and then solidifying when they hit the substrate.

Thermoplastic pool finishes capture the strength and durability of traditional pool surfaces while maintaining the beauty and architectural colour range of aggregate finishes. Customized decorative stencils and depth markers are also available. Trained installers can achieve various effects such as two-tone applications (a darker finish on the pool floor gives the illusion of greater depth), while stairs and other features can be highlighted. Two-tone colours can be melded together to appear and feel seamless.

Three different thermal-spray systems are currently being used in the industry: one is designed primarily for smaller projects and detail work such as the restoration of fibreglass steps, which can be performed on-site and in place. Standard systems are typically used for large pool projects and detail work, enabling installers to cover 14 m² (150 sf) per hour. Finally, high output units, typically used for commercial pool applications, allow installers to cover 23.2 m² (250 sf) per hour.

Benefits of thermoplastic pool finishes:

• Resistant to acid, chemicals, salt, scale, ultraviolet (UV) rays, fading, rusting, staining, and corrosion;
• Smooth, non-scratch, non-chip, non-peel surface;
• High elastic memory;
• Non-porous;
• Excellent colour consistency on hybrid pool substrates;
• No mottling;
• Crack-resistant to -70 C (-94 F);
• pH neutral (lowers chemical needs);
• No volatile organic compounds (VOCs);
• No heavy metals; and
• Energy efficient in both manufacturing and processing.

Surface preparation

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Applying the thermoplastic coating to the surface is a multi-day process. The pool must be clean and dry to apply the epoxies before installation can commence. To do this, the pool must be drained and the surface etched or profiled (when necessary), then cleaned with a pressure washer or trisodium phosphate (TSP), and allowed to dry overnight. Then, all fixtures must be covered or removed to avoid contact with the thermal epoxy. The hydrostatic plug at the bottom of the pool should also be removed to stabilize groundwater.

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The application process is safe when the installer is trained, has a full understanding of the proper safety practices, understands the equipment, and follows all recommended procedures. Pool professionals already have the knowledge required to properly assess the condition of pool surfaces. The surface or substrate of the pool or spa should be made as smooth as possible, prior to application, to avoid any imperfections showing through the finish. Thermoplastic spray finishes will cover spider cracks and minor pool blemishes; however, if the pool shows signs of severe deterioration or etching, preparation must be performed prior to application to avoid noticeable imperfections. If not prepared properly, extensive labour will be required during the install. Therefore, it is much easier and more cost effective to repair the surface first than to try and fill any voids with thermoplastic later.

The installation timeline for a thermoplastic pool finish, for an average size pool, is approximately three days from start to finish:

Day one

On the first day, the main focus is preparing the substrate surface followed by masking. Once the substrate is determined to be sound, repaired, and readied for the thermoplastic application, the next step is to mask all of the surfaces where the finish must be avoided.

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For example, all tiles, copings, light fixtures, drains, fittings, and anything that will not be coated with the thermoplastics material should be masked. A specialized heat-resistant tape (used to define a line between the tiles and the pool surface) and fabric (secured with the tape to cover tile lines and copings) specifically designed for use with a thermoplastic-spray system should be used. The fabric can be used continuously throughout the season—from application to application—the tape is single use only, however.

Do not mask the entire pool surface area, steps and, if applicable, slides and/or diving boards, etc. When applying a new finish on an existing pool or spa, it is best to remove the old fittings and replace them with new ones. Thermoplastic overspray is minimal because the settings can be set for the most economical method of application.

The epoxy used for pool finishes is a two-component, solvent-free epoxy resin, which is specifically designed for use on concrete and similar substrates. When installed, epoxy provides an ideal surface for the thermoplastic coating to bind.

Day two

After the application of epoxy is applied, the first pass of thermoplastic is made as the epoxy starts to become tacky. This first pass is referred to as a ‘hot flock’—the first minimal coat of thermoplastic powder applied lightly over the surface. This action embeds the thermoplastic into the epoxy to form a permanent mechanical bond coat.

Day three

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The topcoat is applied using a consistent side-to-side motion. Thermoplastic installers aim to cover at least 80 per cent of the pool or spa surface with the flock coat application. Passing the gun over the surface is necessary to apply the flock coat. Installers start this process at the bottom of the pool or spa and gradually work their way up the wall with the application. This utilizes the heat from the gun as it radiates up the wall.

• The finish coat is applied in the same manner as the hot flock coat; and
• A smooth continuous motion enables the installer to ‘melt out’ all of the powders and meld them together to achieve a smooth non-porous finish. A different technique is used if surfaces such as steps, ledges, and benches require a non-slip coating. In this case, the thermoplastic material is applied after the first coats have been processed. Non-slip surfaces are achieved when the installer purposely under-heats the material after it attaches to the initial thermoplastic coating, resulting in a smooth, but textured finish.In terms of the ideal weather conditions for application, the air temperature must be at least 5 C (41 F). Below this temperature, the pool finish can still be applied; however, the installer will need to preheat the surface first by passing the propane gun over the pool shell.

Advantages of thermoplastic Installations:

• Clean (no mess or mixing);
• Smooth continuous application;
• No curing time (faster than traditional applications);
• Easily manipulated with no acid etching;
• Application can be stopped and restarted with no visible cold joints;
• Less weather dependency;
• No misting or sun barrier in summer;
• Coating can be repaired without visible seams or joints;
• Does not require feathering;
• No special treatments of fill water; and
• Allows colour continuity between different substrates without mottling.

Most thermoplastic spray finishes come with a 10-year warranty when installed correctly by a trained and certified installer.

The way of the future

Plastics continue to become the way of the future for many different industries and, although thermal-spray technology is relatively new to the pool and spa industry, they now provide an alternative method for builders in the pool and spa construction and renovation markets.

[7]Brian Burton operates a multidisciplinary firm that specializes in website design and development, and technical business writing. The firm also assists companies interested in selling goods and services to governments and institutions. He can be reached via e-mail at burton@award-bid-management.com[8].

Source URL: https://www.poolspamarketing.com/trade/using-thermoplastic-finishes-on-new-pool-installs-and-renovation-projects/

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