Rapid Coat® Joint Compound
Lafarge Rapid Coat® is ideal for use in all phases of gypsum-board finishing: taping, finishing, skim coating, texturing, filling corner beads and trim, and concealing nail or screw dimples.
Rapid Coat also makes an excellent bonding agent for laminating gypsum wallboards together.
Material: Vinyl-type formulation.
Emissions: Asbestos free.
Coverage: Approximately 7.75 gallons (29.25 liters) per 1,000 square feet (100 square meters); coverage will depend on number of beads and amount of trim.
Drying time: Approximately four hours to harden; thoroughly dry in approximately 24 hours. Drying times will vary with temperature and humidity (see Gypsum Association [GA] publication 236).
IMPORTANT: For interior use only. For optimal drying, maintain the room temperature of 68 to 77 degrees F (20 to 25 degrees C) and provide adequate ventilation.
Storage: Up to nine-month shelf life if protected from extreme heat and cold. Maintain storage temperature above 32 degrees F (0 degrees C).
Available sizes: Pails: 4.5 gallons/17 liters; 3.2 gallons/12 liters; 1 gallon/3.8 liters; 0.66 gallon/2.5 liters. Boxes: 4.5 gallons/17 liters; 3.5 gallons/13.25 liters. Some sizes may be available by special order only.
Colors available: White, beige, and yellow.
Standards and Codes:
Rapid Coat is manufactured to conform to ASTM C 475.
Rapid Coat can contribute to the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED) Credit Qualification in several credit categories to assist in obtaining LEED certification. Visit www.lafargenorthamerica.com for more details on specific credit contributions and documentation.
While Rapid Coat gives excellent coverage with the traditional three-coat method (tape, fill, finish), a two-step application method is recommended to obtain the same great results in less time. Apply according to Gypsum Association publications GA-214 and GA-216.
Taping and Finishing Joints:
Step one: Using a steel finishing knife (4 to 6 inches), apply Rapid Coat generously to the surface to be finished (tapered edge). Joint tape should be pressed firmly into the compound to create a good bond, and excess material should be removed. Next, apply a generous "fill coat" with a 10- to 12-inch steel finishing knife or trowel to hide the tape. Remove excess material by feathering the center and edges of the joint. Apply enough Rapid Coat joint compound to fill corner beads and nail/screw dimples. Remove excess material. If necessary, apply a second coat when dry. Rapid Coat can be applied up to ¼ inch thick without cracking.
Step two: A finish coat may be applied when the step one application is thoroughly dry (approximately 24 hours). The material is dry if no prints appear when the surface is pressed lightly with fingertips. Apply a thin coat of the joint compound over the step one application with a 10- to 12-inch steel finishing knife or trowel at a width adequate to fill any voids or shallow spots. Remove excess material by feathering the center and edges of the joint. The surface can be sanded or painted in approximately 24 hours.
Finishing Inside Corners:
Using a steel finishing knife (4 to 6 inches), generously apply Lafarge Rapid Coat to both sides of the inside corner. Fold the joint tape along the center crease and press firmly into the center of the inside corner. Remove any excess material behind the tape and create a good bond with the gypsum board. Allow the compound to dry thoroughly. Apply a second coat to one side, allow it to dry, and apply another coat to the opposite side. Allow the compound to dry thoroughly before sanding or painting.
Note: Rapid Coat is not recommended for use with mesh tape. For finishing with mesh tape, use Lafarge Rapid Joint® setting-type compound as a tape-setting material, following with finish coats of Rapid Coat.
Fasteners and Trim:
Rapid Coat can be applied to fill corner beads and nail/screw dimples. A second coat may be applied, if necessary, when the first coat is dry.
Sanding is not required between applications unless the work is rough. Light sanding, after step two above, should be done after the application is thoroughly dry (180-grit sandpaper or 220-grit mesh cloth is recommended). Wet sanding is recommended to avoid creating dust.
Rapid Coat can be used to skim coat gypsum-board walls. A skim coat leaves a thin film of joint compound over the entire gypsum-board surface, fills imperfections, and eliminates texture differences between the gypsum board and the joint compound. Skim coating is recommended for rooms with critical lighting conditions.
Painting and Wallpapering:
Painting should not proceed until joint compound is thoroughly dry (see GA-236). For best results, a good-quality gypsum-board primer should be applied, in accordance with the primer manufacturer's instructions, before painting or wallpapering.
Rapid Coat can also be used to texture walls and ceilings. For best results, a good-quality gypsum-board primer should be applied, in accordance with the primer manufacturer's instructions, before texturing. Rapid Coat can then be applied to the dry primer surface up to ¼ inch thick with a roller, sponge, brush, or trowel to create the desired effect. Overpaint when dry in accordance with the paint manufacturer's instructions.
Rapid Coat washes off easily with warm water. Tools should be dried thoroughly to prevent rusting.
Product and Safety Precautions:
Material safety data sheets (MSDSs) are available at the link below.
Rapid Coat Joint Compound