Delaminated areas may be patched if small, but larger delaminations require replastering. Occasionally, some plaster areas completely pop off, exposing the underlying surface. Ground movement such as during earthquakes, can also initiate bond failure. It may manifest itself within a month or two or several years later when the pool is drained and the plaster dries out. This defect is usually caused by improper surface preparation to create a good bond during a replaster. Delaminations are usually first seen as a round surface area that has raised or pulled away from the wall, often with small cracks and nodules forming. Spalls may be sanded, although the pool may need to be replastered if large areas have spalled.ĭelaminations – This is the separation of an entire new layer of plaster from its underlying substrate, whether that is old plaster, gunite or shotcrete, etc. Spalling may occur immediately, or years later when the pool is drained, etc. When water evaporates from the surface faster than mix water bleeding up can replace it, and then when that surface dry crust is troweled, a weakened subsurface zone is created that will be prone to spall. This usually results from improperly timed troweling, or from hot, windy or dry days. It can also be caused by adding too much water while troweling. It is caused by the over-troweling of the surface when the underlying paste is wet but the surface cement laitance is dry. Spalling – Spalling is the flaking or peeling of a thin layer (1/8 inch or less) of plaster, usually in small areas on steps and shallow end floors. Fortunately, the white scale can be removed by either sanding or an acid treatment. White discoloration may be calcium scale developing due to imbalanced water, such as high CH, high TA, and overly high pH. These discolorations are permanent, unless major sanding is performed. These colored plasters may also be discolored (white streaking or spotting) from the addition of water to the surface or to trowels applied to the surface during finishing. "Organic" and "Blue" pigments are prone to become bleached out by chlorine, and should not be used in pool plaster applications. Uniform discoloration may be caused by using incompatible admixtures: specifically color pigments and calcium chloride. Whitened Discoloration of Colored Plaster – In time, integrally dark colored pool plaster may begin to show whitening (lighter color) either uniformly or in patterns. See this thread: White Spotting of New Plaster Pools This type of problem usually takes several months to show up. may also display this non-removable deterioration. Disturbed zones along accent or surface tile, around fittings, etc. Beginning as excess porosity around the disturbed aggregate, soft spots expand and sometimes coalesce into larger affected areas as cement components are dissolved away over time. This late hard troweling disturbs surface aggregate, and added water penetrates around that aggregate and spreads laterally through the porous paste caused by accelerated shrinkage. White Spotting and Streaking – New Plaster (white or dark colored) may develop smooth white (lighter color) porous (soft) spots and streaks (sometimes incorrectly termed as “spot etching”) resulting from the addition of water to the hardened surface during late hard troweling in plaster containing excessive calcium chloride. See these threads: How White Pool Plaster Can Turn Gray Severe mottled color variation from calcium chloride or finishing issues may occur quickly once filled with water, or take several months to become visible. Late hard troweling can cause “trowel burn” which darkens the plaster color in localized areas. Gray (or grey) mottled discoloration (also known as “water entrapment” or “hydration”) is smooth to the touch and difficult to lighten, may be remedied by acid washing, sanding, or torching the surface, but these processes are generally detrimental to a plaster finish and the discoloration often returns later. Plaster Discolorations – New white pool plaster can discolor (darken or turn gray) from adding excessive calcium chloride set accelerator, from late hard troweling, from thin and thick areas due to an uneven shell, etc.
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