How to Paint Over a Kool Deck

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The Keystone Kool Deck was invented by the Mortex Corporation in the early 1960s. Kool Decks are most often used near swimming pools, walkways and outdoor patio areas. The colored textured cement surface of the Kool Deck system is comprised of a blend of synthetic iron oxide pigments and natural fibers that help lower the surface temperature in the deck. The Mortex Corporation recommends the use of Systex Deck Paint when painting over your Kool Deck.


Step 1

Prepare the surface of your Kool Deck before painting and examine it for any structural defects. Spray a strong water blast from a high-pressure hose nozzle over the entire area to remove surface dirt and debris.

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Step 2

Scrub the surface of your deck with a stiff brush and a solution comprised of 1 tbsp. dish detergent and 2 tbsp. trisodium phosphate to one gallon of warm water. You may want to use a long-handled push broom to remove any embedded dirt, oils or paint residue for easier scrubbing.


Step 3

Rinse the area with plain water and examine areas that may need patching or repair. Minor repairs should be corrected prior to painting your deck by patching them with a hydraulic cement or joint filler. Apply the cement according to the manufacturer's directions and allow it to dry thoroughly before continuing.

Step 4

Acid etch the deck surface to prepare it for the paint. This is a dangerous operation that should be done carefully according to the manufacturer's instructions on the muriatic acid. Always wear safety goggles, a protective facial mask, thick rubber gloves and long sleeves when working with muriatic acid.


Step 5

Rinse the area thoroughly to remove any remaining acid. This should leave the surface rough for better adherence of the paint. Perform a quick wash on the deck a second time with the soap and trisodium phosphate solution. Rinse well.

Step 6

Mix the Systex deck paint well with a drill and paddle attachment until a uniform consistency and color is achieved. Do not prime your deck with anything before using Systex deck paint; this is a self-priming paint.


Step 7

Apply the paint with a paint roller that is no larger than 3/8 inch in diameter. Temperatures should be above 50 degrees Fahrenheit and no hotter than 90 degrees when applying the paint. Paint should be applied on a lightly dampened surface for best results at a time when rain is not probable for 48 hours.

Step 8

Apply the paint with even strokes of the roller across the deck surface, beginning in corners or walled areas and working your way outward. You may use a paint brush to fill in tight areas near corners and walls. It is best to apply several thin coats rather than one thick one.


Step 9

Allow two hours of drying time in between coats. Your deck should be fully dried within 48 hours. If rain occurs during this time, add one day of drying time for each day of rain.

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