The Life (and Death) of a Pool Finish

As any pool pro knows, dealing with finish breakdowns is inevitable.

There’s mottling and color variation, rough scale from high Calcium Saturation Index, dusting from low CSI or aggressive acids, calcium nodules, scale rings, cracks that leak — the list goes on. Some root causes trace back to water chemistry, while others stem from application, curing or environmental factors. In some cases, design plays a role.

The bottom line is that even great plaster can’t survive long-term aggressive or scaling water.

Water chemistry vs. application

Spencer Gothberg, president of sales at Infinity Pools with office locations in Utah, Colorado and Idaho, says his team sees a bit of everything when it comes to finish breakdowns.

“The key is understanding what’s cosmetic versus what’s structural,” Gothberg says. “A small variation in color or texture might just be part of the natural curing process — it doesn’t hurt anything. But when you start seeing rough spots, soft areas or flaking, that’s not cosmetic anymore.”

He estimates about 60% of finish breakdowns are caused by water chemistry and 40% by application.

“You can do everything right on the trowel, but if the water’s off, it’ll destroy that finish fast,” Gothberg says. “Low calcium hardness and low alkalinity are the big killers. When the water’s hungry, it goes after the finish.”

Poor application practices — overtroweling, using too much water or improper curing — can also lead to problems. But most real damage happens after the fill, when the water starts pulling calcium out of the surface because it’s too aggressive.

Even before start-up, fill water chemistry can make or break a finish. Low-calcium source water immediately begins dissolving calcium hydroxide — the soft, soluble byproduct of cement hydration — effectively etching the surface before the pool is even in service.

Start-ups set the stage

This is where start-up procedures make all the difference.

“The start-up sets the tone for the life of the pool,” Gothberg says. “Those first few days are critical — the finish is still hydrating and hardening. If the water is out of balance early on, it’ll start dissolving calcium right out of the plaster.”

Alan Smith, co-founder and chairman of MicroGlass and former CEO of Alan Smith Pools, notes hydration and curing — though often used interchangeably — are different processes that both affect surface quality. Hydration is the chemical reaction that hardens cement; curing is the control of moisture and temperature that lets that reaction complete evenly. Both are essential for a dense, durable finish.

Ryan Ross, lead service tech at Avree Custom Pools in Houston, Texas, explains that the first 28 to 30 days after applying a finish are “everything.” His team makes a point to do a continuous fill — no stop lines — and protect the pool from debris and rain, since dilution can drive CSI negative.

After the fill, Ross’ team brushes twice a day for the first week, and daily during weeks two through four. No salt is added, and the saltwater generator and heater remain off for the first 30 days.

When issues arise, Ross’ crew starts with the least invasive fix — chemical treatment, targeted polish or spot repair — and follows up with clear cost allocation and prevention education.

Bonding, surfaces and chemistry 

In the Northeast, Rob Romano, general manager for the Long Island territory of David Cooke Plaster Co., says bonding issues are among the most common failures. 

“You’re only as good as your prep,” Romano says. “If the surface isn’t properly prepped before the bond coat goes on, it won’t adhere, leading to delamination.”

Romano emphasizes that while water chemistry management is important for every finish, pebble surfaces are generally the most forgiving. Smooth finishes like plaster and quartz have more exposed cement reacting with water. That cement’s high pH drives scale formation, which shows up faster and more visibly on dark, smooth finishes. Since calcium scale is white, it can lighten dark colors within weeks.

It’s worth remembering all pool finishes share a common denominator: cement. It’s the binder that holds everything together — and also the weak link.

Smith adds that many of the industry’s standards stem from early research at the National Pool Industry Research Center located on California Polytechnic State University campus, which studied how cement hydration, water chemistry and curing conditions interact. Those findings helped establish many of today’s start-up and maintenance guidelines.

Protective additives and preventive care 

Additives and surface treatments can help prevent early cosmetic issues such as scale. One example is MicroGlass, a protective spray for new or remodeled pools designed to extend the life of the finish and reduce discoloration, etching and plaster dust.

Smith explains that products like MicroGlass chemically convert soft calcium hydroxide into calcium silicate hydrate, a harder and more stable compound that strengthens the finish at the molecular level. The result: a denser surface less prone to etching or staining. 

“With proper chemistry, you can maintain any pool finish forever,” Smith says.

Smith uses this analogy: Think of a pool as a stomach and the plaster as its lining. When water chemistry is off (low calcium or low alkalinity), it’s like heartburn — the water starts “burning” the surface. Adding calcium and alkalinity is like taking Tums, as it neutralizes the acidity and protects the lining.

Even reliable testing, Smith adds, can introduce error if reagents degrade or temperature and sunlight affect readings. Regularly calibrating kits and checking reagents helps ensure accurate results — especially when documenting start-up water balance.

Accountability and collaboration

When diagnosing finish issues, Gothberg says his company takes a clinical approach. 

“We deal in facts, not finger-pointing,” Gothberg says. “We gather water tests, start-up records and application details. If it’s a workmanship issue, we stand behind it. If it’s water chemistry, we show the homeowner exactly what happened and why.”

Romano uses a similar method. 

“The blame game doesn’t solve anything,” he says. “The homeowner just wants resolution. Builders, applicators and service companies all share responsibility to work together and keep the customer happy with their new finish. That’s the goal every time.”

Clear documentation and expectation-setting up front — including start-up logs, water tests and product disclosures — can defuse disputes before they start.

Longevity through teamwork

Ultimately, pool finishes are living materials that react to their environment.

“A beautiful surface isn’t just about how it’s applied; it’s about how it’s cared for,” Gothberg says. “When the builder applies it right, the start-up tech balances it right and the homeowner maintains it right, that finish can easily last 20 years or more. It’s all about teamwork.”