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Plaster Pools (cont.)
Want to increase the life of your plaster?
Barring problems in the
mixing, application and curing
processes, the pool owner, or service
company controls its condition and life
span. Keeping your water chemistry in
balance and most importantly, preventing corrosive
water environments of low pH and low alkalinity will reduce wear and
tear.
Maintain your pH levels at between
7.4 - 7.8.
Alkalinity should be kept between 80 - 120 ppm. Lower
levels may etch your plaster, which provides a safe harbor for dirt and
algae to grow,
isn't attractive and is rough to the touch.
Heavy metals cause stains.
Metallic salts cause scale. These salts
are primarily forms of
calcium
and
magnesium which can deposit on your plaster, pipes and equipment.
They may arise from the use of calcium based sanitizers or the fill water may have
high calcium hardness levels.
Keep your calcium hardness levels between 200 - 400 ppm.
A level that is above this may find it
easy to precipitate out of solution.
This is known as a scaling condition. Conversely, water with low
levels of hardness will produce an aggressive condition. In aggressive conditions
(soft water), the water will take the calcium it wants directly out of your plaster,
resulting in plaster breakdown and bond failure.
Pool plaster is pitted
or etched?
If your plaster has surface
irregularities, which may take on a
beige hue, you have what's commonly
called etching. This etching can be
caused by low
pH or alkalinity; an
acidic condition. It may begin within
the plaster, from the original mix on
application, or etching may start from
the gunite side of the plaster and work
itself from the outside in.
Pool plaster has large,
dark areas?
You may be seeing the gunite or shotcrete beneath the plaster beginning to show through. You
better start budgeting for that re-plaster.
Pool plaster has small
cracks?
Known as crazing or checking, the tiny,
barely visible cracks are usually caused
by extreme temperature variations,
especially during initial curing. These
are not actually cracks, and pose no
structural hazard or danger of leaking.
Acid washing could remove the
crazed layer. Larger cracks should be cut out in a butterfly or dovetail fashion with a
4" or 7" grinder, and filled with a plaster patch mix or a
flexible sealant can
be used where further movement is suspected.
Plaster has
delaminated?
Known as bond failure, this will occur
as areas where the plaster has popped
off. Usually seen on re-plaster jobs,
where the plaster to plaster bond may never be as strong as the original plaster to
concrete bond. This is repaired with a plaster patch. Plaster normally does not delaminate
from the gunite; this bond failure can more easily occur, plaster to plaster. Chip
away any loose material around the edge of the delaminated area. This will sometimes make
the patch much bigger than the hole is to begin with. Chip & chisel to break up and
rough up the surface, clean and brush on a bonding additive. Then pour in premixed white
Portland cement and marble dust; 2:1. Use bonding additive (like Acryl 60) to mix the
plaster with. Trowel smooth with a round ended trowel. Keep the patch from drying too
quickly by doing this repair in the evening and covering with moist towels or burlap.
Plaster patching: The delaminated area is chipped outwards until good bond is
found. The surface is roughened and plastered is
troweled in place by hand. Cost depends
on the size and location of the patch. Plaster patching material can be purchased at most
pool stores. It is a mixture of white Portland cement and marble dust. A bonding additive
such as Acryl 60 should be used when applying.
Re-plastering:
The pool is drained and acid etched several times.
Chipping and cutting around all fittings and under the tile allows the new coat to be
feathered. A scratch coat is applied first, followed by a finish coat. The pool is filled
immediately; the plaster cures underwater. The surface must then be brushed twice daily,
with vacuuming and continuous filtering to remove the plaster dust. Cost for a re-plaster
is based on surface square footage. Expect $2,500 - $4,000.
Once upon a time, plasterers would
plaster a pool in any color, as long as
it was white. Black or gray plaster is
now becoming more common, and other
colored additives can produce varied
color effects. Any colored plaster will
show more mottling than white pools,
however. If you plaster in any color
other than white, expect streaking and
uneven hues. Don't expect flat black
color, for example.
Pool painting: Before plastering became
popular, pool shells were painted. These
were low grade paints that barely lasted
one season. The annual drain & paint was
gladly given up when plaster became
popular. The underwater epoxies used
today offer a 7 year life span for about
half the cost of re-plastering. Paint adheres very well to
properly prepped plaster, and offers a wide variety of colors and graphic capabilities.
Pool painting is a second class choice to re-plastering. It may be half the cost, but will
last only half as long (at best). If you start painting, you keep painting, unless you
sandblast it off to allow re-plastering. We tend to discourage our customers from painting
a pool. A few dollars saved in the short run will cost more in the long run.
Pool
painting: The pool is drained and degreased.
It is then acid etched and degreased again. After drying, a primer coat is applied,
followed by two coats of the chosen color(s). Again with the drying, and the pool is
filled. Price will vary according to size and prep factors. Expect $1,900 - $2,800. Pool
artwork varies.
Want to Re-plaster the pool yourself?
I would discourage this.
Plastering is nothing short of an art
and science. Experienced.... (continued.....)
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