Just Replastered And Balanced But Callback Rough Finish: Post-Service Decision Tree

Why this matters

A freshly replastered pool that was startup-balanced to plaster-industry guidance and is now generating a callback for rough or gritty finish is one of the higher-stakes calls in pool service. The plaster company will blame the chemistry; the chemistry tech will blame the trowel finish; the customer will blame whoever shows up. The truth is usually one of a small set of post-service conditions that this tree separates. Getting the disposition right protects the finish warranty, the customer relationship, and the next quarter's water chemistry.

Symptom presentation

The pool was replastered within the last 30 to 90 days. Startup chemistry was logged daily through the initial curing period. Plaster finish was reported smooth at handoff. The customer now reports the finish feels rough under foot, swimmers' feet are getting scraped, or the surface looks etched, dull, or streaked. Water clarity may be normal, slightly cloudy, or carry visible suspended particulates. Filter pressure may have risen as plaster dust loaded the media.

Quick checks

Pull a full chemistry panel: FC, CC, pH, TA, CH, CYA, salt (if SWG), TDS, and water temperature. Compute LSI with the measured values. Inspect the finish at the affected area: photograph against an angled flashlight to reveal etching versus dust versus calcium nodules. Run a finger along the surface; gritty texture under water that rinses off with hand pressure is plaster dust or calcium precipitate sitting on the surface, gritty texture that is part of the surface itself is etched or under-troweled plaster.

Check the service log for the startup procedure. A pool started up with the bicarbonate startup, the traditional startup, or the no-drain startup each has different signature failure modes. A pool that skipped the initial brushing schedule, that was filled with high-CH source water, or that was acid-bathed during startup will all produce distinctive post-service complaints.

Isolation tree

Branch A: plaster dust on a sound finish. The grit is on the surface, not part of it. LSI is in the healthy band, CH and TA are stable, the finish looks smooth in photographs. Plaster dust is normal in the first 30 days; it should be brushed daily during the initial cure and filtered out. Disposition: confirm brushing schedule, clean the filter, top up chemistry if needed, document the expected dust-clear window. This is a customer-expectation issue, not a defect.

Branch B: calcium nodules or scale on a sound finish. White nodules or sheets of crystalline deposit on the plaster. LSI runs above plus 0.5, CH is above 400 ppm, or pH and TA are at the high end of their bands. The water is scaling onto the fresh plaster, which is the most chemically reactive substrate it will encounter. Disposition: bring LSI into the zero to plus 0.3 band, brush the affected zones gently, document the chemistry that drove the deposit. Communicate the cause; the customer will hear "scale" and worry, but on fresh plaster this can be reversed without finish damage if caught early.

Branch C: etching on a soft or under-cured finish. The finish itself is rough; running a fingernail catches the surface, the texture does not rinse off. LSI runs below minus 0.3 at any point during startup, pH dropped below 7.0 during acid additions, or TA fell below 60 ppm. The water dissolved cement matrix from the plaster surface. Disposition: stop further acid, balance LSI to the slightly positive side (zero to plus 0.3) and hold, monitor for finish stabilization. Etching will not reverse, but progression can be stopped. Communicate to the customer and the plaster company; this is a warranty conversation that needs the chemistry log.

Branch D: streaking or color variation on the finish. Long vertical streaks, dark patches, or color zones in the plaster. Cause: variable trowel finish, calcium chloride accelerator used unevenly in the plaster mix, or chemistry distribution during fill (acid or chlorine sitting against the wall during the initial fill stages). Disposition: chemistry is unlikely to be the only cause; this is a plaster application issue. Document the chemistry log to demonstrate the water did its part, escalate to the plaster company.

Branch E: copper or iron staining from heater or fill water. Pinkish, green, or brown staining following the return jets or at the deep end floor. Cause: metals in fill water reacting with chemistry during the first chlorination cycle, or copper coming off a heater heat exchanger that was scaled or corroded. Disposition: sequester metals before further chemistry adjustment, test fill water for metals, inspect the heater bypass during initial startup on the next fresh-plaster job.

Branch F: trowel marks revealed as gritty by water. The finish was burnished by the plaster trowel in some zones and not others; the burnished zones feel slick, the un-burnished zones feel gritty. Common on hand-finished plaster. Disposition: confirm with the plaster company that the texture variation is within their acceptance band; chemistry will not improve this. Customer communication is the deliverable.

Confirming diagnosis

Pull the daily chemistry log from the startup period. A startup chemistry tech should have logged FC, pH, TA, CH, and LSI at least once per day for the first 14 days. If the log shows LSI excursions below minus 0.3 or above plus 0.5, the cause of the current complaint is in the log. If the log is clean and LSI ran in the zero to plus 0.3 band throughout, the cause is application or fill-water related, not chemistry.

Photograph the affected zones with a contrast card and a known scale (a coin), and pull a sample of any deposit that scrapes off for visual comparison against scale, nodule, or dust references. Confirm by re-testing chemistry against the current readings; a pool that scaled during startup is often still scaling at the visit.

Remediation

For dust, brush schedule and patience. For incipient scale, LSI correction and gentle brushing. For etching, stop the cause and stabilize chemistry on the slightly positive side. For application defects, escalate to the plaster company with the chemistry log in hand. For metals, sequester and identify the source. For trowel marks, customer education.

Document the post-service handling clearly in the customer record so the next visit's tech does not undo the correction by chasing a different target.

References

• PHTA NPC, National Plasterers Council Startup Guidance
• PHTA/APSP/ICC-11, Water Quality in Public Pools and Spas
• NSF/ANSI 50, Equipment and Chemicals for Swimming Pools, Spas, Hot Tubs, and Other Recreational Water Facilities