Sunday, August 21, 2011

How to Acid Stain Gypcrete Or Any Gypsum Based Underlayments

These days coloring the concrete surfaces both old and new using acid stains (also called reactive stain or chemical stain) is very favorite because of its unique looks and cost effectiveness. Acid staining is a process in which an aqueous explication of metallic oxides and inorganic acid is sprayed over an existing concrete surface. The acidic explication of metallic oxide reacts with lime (Calcium Hydroxide) present in the concrete yielding insoluble, colored compounds that come to be a permanent part of the concrete. Therefore, one of the basic conditions where coloring concrete using acid stains is going to work is the presence of lime in the concrete. Quiet often population who have just bought a home or condo, take off the rug or vinyl tile, and find something underneath which they believe is concrete. When they spray the acid stain or reactive stain and wait to get disappointed because they do not see any convert in the color on their concrete surface. This is because the substrate that looks like concrete is in fact gypsum based 'Gypcrete'. Builders often use this on upper floors to level out areas of sub flooring and supply a good base for other types of floor coverings. Unfortunately, staining Gypcrete does not yield any desirable results since it does not contain any lime; moreover it is too soft and no ifs ands or buts abraded. Therefore 'Gypcrete' cannot be used as a wear layer.

Since Gypcrete surfaces cannot be used as a wear layer and acid stains do not work on them, it is usual convention to apply a 1/16inch polymer modified concrete resurfacing material (also called micro-topping or skim coat). Please find below the steps complex in resurfacing Gypcrete and acid staining with a micro-topping or skim coat -

LOWES DRYWALL

a. Sweep the Gypcrete covering and dry vacuum the covering thoroughly. Rake out the joints where drywall meets the floor. Clean the adjoining areas even those not being resurfaced with a micro-topping.

b. Install masking paper (plastic) at least 48" high on the surrounding walls. Spray a light mist of water just to damp the covering (Do Not Flood!)

c. Using a brand new rayon mop, apply the first coat of acrylic primer (Cp1000) after diluting it with water @ 1:1 ratio. After waiting for at least 60 minutes, apply second coat of diluted acrylic primer and let it cure overnight (or 10 hours at least) before proceeding to the next step.

d. Apply an additional one coat of acrylic primer, this time non-diluted and let it dry for 30-60 minutes. The third coat of primer can be applied using garden sprayer (i.e., available in Home Depot or Lowes).

e. Apply a thin coat (1/16") coat of micro-topping or polymer modified overlay using magic trowel. Please consequent the link for specific education on application of polymer modified micro-topping, Sgraffino. Allow the micro-topping to cure for at least 24 hours. In damp and cold conditions (basements), wait for at least 48 hours before proceeding to the next step.

f. Apply acid stain on the thoroughly dried micro-topping. Please consequent the link for specific education on application of an acid stain, Patinaetch. Allow the acid stained covering to dry for at least 24 hours before proceeding to the next step.

g. The micro-topping needs to be protected with a good potential sealer. Apply one coat of water based epoxy sealer, Perdüre E32 followed be an additional one coat of water based polyurethane, Perdüre U46. Allow at least 6 hours in the middle of the application of epoxy primer and polyurethane topcoat. The sealed covering will be ready for use after 24hours. Of course, it takes at least 3 days for full cure.

How to Acid Stain Gypcrete Or Any Gypsum Based Underlayments

LOWES DRYWALL

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