Used for decades in hundreds of thousands of pools around the globe, marcite is the material most commonly used for plastering a pool. In fact, many people use the term “marcite” and “plaster” interchangeably. Marcite is a mixture composed primarily of white Portland cement, marble dust, and fortifying additives to boost strength and water resistance. Mixed with water, it forms a smooth material that specialty crews use to coat the inside of a pool. They apply it over the concrete surface with hand-held trowel tools to create a smooth, hard exterior. Marcite is also the most affordable option for a new pool or replastering an existing one. With properly maintained pool water, it will last 8 to 12 years. However, in regions with particularly “hard water” (water with high alkalinity and calcium), the pool water wreaks havoc on marcite’s endurance. In these cases, quartz or pebble is almost always a smarter choice. Although marcite starts out as white, the wet mix can be dyed in a small range of blues and greys to create a dark-bottom pool, which is popular for lagoon-style designs. However, the deeper the added color, the more easily the finish will show imperfections, such as streaks and fading. In fact, some pool builders are reluctant to use dyed plasters because they almost magnify any minor blemishes. Because marcite constantly reacts to chemicals, minerals, and the pH/alkalinity in pool water, this kind of finish is more susceptible to problems if your water chemistry is not properly and consistently balanced. Consequences can include staining, etching, mottling, erosion, and discoloration. It’s hard to overstate just how pivotal the role that water quality plays in extending—or shortening—the life of a marcite finish. Because of its increased vulnerability to visual blemishes and its requirements for stringent water quality, marcite deteriorates faster. Bottom line, it’s the pool finish that will get the job done—but do so with the least durability and the shortest lifespan. That’s why more and more pool buyers and pool owners are rethinking the use of marcite. Instead, when they are picking out materials for a new pool or refinishing their current one, they upgrade to colored quartz aggregates or pebble finishes.