Liberally brush the acid solution on the surface. The acid
will bubble on the surface when applied. As soon as this bubbling ceases, rinse
the solution off with clear water. The surface should feel like fine
sandpaper when properly etched. Splash a small amount of water on the surface to
see if it is sufficiently etched. If the water soaks in fairly quickly, the
surface is properly etched. If the water stands on the surface, another etching
will be required or switch to a stronger acid solution. It is of utmost
importance that you wash the pool again after etching. The tri-sodium
phosphate in the pool washing solution will neutralize all traces of acid left
on the surface after etching. After this second washing, allow the pool to dry
before coating. However, if you are using POXOPRIME II epoxy primer, you
may proceed with priming the pool. POXOPRIME II is compatible with wet surfaces.
Caution: Do not mix in a galvanized container.
The following is the Technical Bulletin from The Olympic Product
Guides:
Bulletin 141
Acid Etching and Surface Cleaning Pools
Pool surfaces MUST be completely clean and free from slime, scum, body and
suntan oils, algae, calcium, and other surface residue before they can be
satisfactorily painted or repainted. Paint will not bond to contaminated
surfaces. If you paint over any surface residue or foreign matter, it (the
foreign matter) will soon disintegrate and fall away from the surface taking the
paint with it. New and old plaster and bare poured concrete pool surfaces must
be clean and free from oil, grease, silicone, or wax type releasing agents
before they can be etched. Pools are prepared for painting by a three step
procedure: (1) WASHING (2) ACID ETCHING and (3) WASHING. The how-to and why of
each operation will be covered below.
WASHING POOLS
It is important to know that ACID WILL NOT REMOVE SUNTAN OIL, BODY OILS,
DILUTED HAIR SPRAY OR ANY OILY OR GREASY SUBSTANCE. These must be removed
with #910 Pool Washing compound or tri-sodium phosphate before repainting.
Always use tri-sodium phosphate or pool washing compound before and after
etching; then scrub and hose off with clear water.
Pools are scrubbed easier by using Olympic #910 Pool Washing Compound. If this
is not available, use tri-sodium phosphate. Mix either of these powders 8 oz.
(230 grams) to each gallon (3.9 liters) of water. Warm water is best for the
compound dissolves faster. Mix about five gallons (18.8 liters) of this solution
for each 1,000 sq. ft. (94 sq. meters) of surface to be scrubbed. Most scrubbing
is done with a long handled block brush which has nylon or other stiff bristles.
By using brushes of this type while scrubbing the pools, you also remove loose
particles which could result in poor adhesion of the paint.
Best procedure is to scrub the walls first. Rinse the walls as you scrub so the
alkaline solution does not dry on the surface. When that happens, the remaining
alkaline salts could cause a loss of adhesion when the pool is to be painted.
These could leave a "soapy" residue which would prevent the adhesion of the
paint. Always use a chemical type softener and cleaner such as Olympic #910 Pool
Washing Compound or tri-sodium phosphate. Often when a pool is well scrubbed,
the appearance will be satisfactory without repainting or with only a touch up
job in a few spots. Again, it may only be necessary to repaint the floor or one
or more wall sections. Always hose of #910 Pool Washing Compound or tri-sodium
phosphate with clear water.
ACID ETCHING POOLS
Why acid etching? Acid etching opens millions of microscopic pores. By opening
the pores, the prime coat of paint is able to penetrate into the porosity
created by the acid etching and create an excellent adhesion for succeeding
coats. Acid etching performs another very important function as it removes the
"laitance" from the surface. "Laitance" is the fine sand, cement and grit which
migrates to the surface. It forms a thin layer approximately 1/32 of an inch,
(.079 centimeter) thick and is the weakest part of the slab. Unless it is
removed by etching, it will lose adhesion and as it falls away it will take the
previously applied paint with it. Acid etching is the most practical way to
remove the "laitance."
MIXING AND THE APPLICATION OF ACID
All persons participating in acid etching should wear rubber boots, rubber
gloves, and wear goggles. The etching solution should be mixed in a plastic
bucket. Most commercial muriatic is either 20% or 30% hydrochloric acid. Mix one
part of 30% muriatic acid with two parts of water. This makes a 10% acid
solution. Be sure to check the strength of the muriatic when you buy it. If it
is a 20% acid, then mix one part of water to one part of acid to secure a 10%
solution. For a 15% solution, mix 30% acid 50/50 with water. For 20% muriatic,
mix one part of water to two parts of acid.
CAUTION! ALWAYS POUR THE ACID IN THE WATER.
NEVER POUR WATER IN THE ACID.
Pour the acid solution on the surface and brush it out with a long handled deck
brush. Etch a small area at a time. As soon as the acid ceases to effervesce it
should be hosed off with clean water. About 5 minutes is the average time for
the acid to perform the etching function. Do not permit the acid to dry on the
surface, as it will be difficult to remove. Figure one gallon (3.79 liters) of
etching solution to each 100 sq.. ft. (9.39 sq. meters) of surface. Properly
etched, the surface should feel like fine sandpaper. On vertical surfaces, the
etching solution should be swabbed on liberally with a mop, long handled deck
brush, or garden sprayer. Drop or splash a small spot with water. If the water
soaks in fairly quick, the surface is sufficiently etched. If it remains on the
surface, it needs additional etching with a stronger solution.
Variations in the hardness and the density of plaster or concrete may result in
smooth areas after etching. These spots or areas should be re-etched with a
stronger (15%) solution. Be liberal with the acid solution. The more you put on
the surface, the better the etch.
After the etching is completed and the surface is hosed off, the surface should
be scrubbed with #910 Pool Washing Compound or tri-sodium phosphate solution
using 8 oz. (227 grams) of the compound to each gallon (3.79 liters) of warm
water. Use a deck brush and plenty of "elbow grease" on this final scrubbing
operation in order to remove all remaining traces of the acid. Any remaining
acid could form soluble acid salts and result in a probably paint failure. The
surface should then be hosed off with clear water.
Most pools in good condition, except for discoloration and staining, can be
"cleaned up" to a nice appearance by this acid cleaning. This will also remove
light algae and chalk. Heavier concentrations of algae can be removed with
Clorox or with a paste made of powdered chlorine and water. Apply paste with a
scrub brush.
Pools painted with Olympic ZERON and POXOLON (epoxy) pool coating can usually be
cleaned to a "new paint" appearance. For repainting either of our epoxy
coatings, they should never be repainted until the finish is almost worm or
eroded from the surface. This means that the coating should be "cleaned up"
until requiring paint, which usually takes from five to seven years.
UNPAINTED CONCRETE OR PLASTER must also be scrubbed with #910 Pool
Washing Compound or tri-sodium phosphate solution, if they have been in service.
If they have not been in service, and if the concrete or plaster is new, they
require acid etching. Then, the acid must be neutralized by washing the pool
with a tri-sodium phosphate solution.
At one time many pools were painted or grouted with a low cost cement base
paint. This type of paint was so unsatisfactory that it is seldom used today. It
was never intended to be used in swimming pools, as it does not have any of the
desirable characteristics required of swimming pool coatings. This type of paint
has always been good for interior and exterior aboveground masonry and concrete
blocks. It is a very poor substitute for the standard pool paints formulated
from chlorinated rubber or epoxy resins.
Cement paints are coarse and gritty and provide a poor appearance. They quickly
become stained and are a perfect base for algae concentration. When any of these
materials or other residue are attached to this surface, they are very difficult
to remove. This "type" of paint will usually disintegrate within a limited time.
If a surface painted with cement paint is to be coated with a good pool paint,
the remaining cement paint should all be removed. Normally it can easily be
removed by scrubbing with a strong muriatic acid solution at least twice. The
acid should then be neutralized with TSP and hose off with clean water. Sand or
water blasting is still the best way to remove cement paint.
--------------------------------------------------------------------------------
CAUTION!
Do not mix in galvanized container. Close container after each use.
Avoid contact with eyes, skin or clothing. Rubber gloves, rubber boots, and
goggles should always be worn by the person etching concrete. In case of
contact, flush off immediately with water. For eyes, get quick medical
attention. Protect evergreen shrubs, grass and plants from solution.
KEEP OUT OF THE REACH OF CHILDREN.
