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Plaster Pools
Concrete
pools are the oldest form of building pools. The
process starts with digging a hole in the ground and lining
the hole with rebar. Then the drains, skimmers, return
lines, and in-floor cleaning system are set into place. After that, the pool is shot with gunite. Then, the tile
and coping stones are set in place. Finally, the pool
is shot and
troweled with plaster. Once the
plaster is finished, the company usually starts filling the
pool with water.
Once the
pool is full, the system is started up and balanced with
chemicals. This is the time that takes the most work,
usually a
lot of brushing and backwashing due to dusting from the
new plaster.
Also called whitecoat or marcite, plaster is
an age old process of finishing many structures. Used underwater, it provides the
watertight seal that the more porous gunite or shotcrete beneath it cannot. Plaster
finishes provide twenty years of service under ideal conditions, however, ours is rarely
an ideal world. The plaster surface is meant to degrade slowly, eventually requiring a
fresh coat.
Plaster has shading
variations?
Known as mottling, and distinct from
surface stains and deposits, mottling
may appear as grayish hued areas. Rarely
do I see a plaster job that is white
like milk. They're usually white like
clouds. Being a natural product,
mottling is inherent in any plaster job
and should not be considered a defect.
There has been much research on the
subject in recent years, however no
consensus has been reached on the causes
and cure of mottling.
Plaster is
stained?
Different from mottling, stains are
usually localized and distinct in color
from the plaster. Most stains are caused
by heavy metal minerals coming out of
solutions and depositing themselves on
the nearest structure they find. They
may also remain suspended in water,
providing dramatic new color schemes. Below is a chart listing common
metals found in pools, where they came
from, and their identifying colors.
Plaster has
crystalline deposits?
Your pool water has precipitated metallic
salts out of solution. This will create
areas of the pool which are extremely
rough and scaly. There are several
solutions to remove these deposits,
including
acid washing, sanding and
the use of a calcium deposit dissolving chemical called
HydroQuest.
|
Metal |
Sources |
Colors |
|
Calcium |
Plaster, grout, mortar, cal-hypo
chlorine shock |
white crystals or precipitate |
|
Cobalt |
Fiberglass shells |
red, blue, gray or black |
|
Copper |
Copper algaecides, ionizers,
corrosion of copper
and brass
pipes, fittings and heaters |
blue, green & blue/green black,
dark red or teal |
|
Iron |
Well water, corrosion of iron
pipe and fittings |
dark red, brown, black, gray or
green |
|
Manganese |
Well water |
pink, red, black or red |
If any of the above causes apply to you, your pool
should be using a sequestering agent which aids your water balance in preventing
the metal from dropping out of solution and staining underwater surfaces. Most
stains left by precipitated metals can be removed by one form or another. An
acid wash every few years will keep a pool looking nice.
(continued)
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