Application Procedure
Job Conditions - Air and substrate temperature for application of OCS must be 40°F (5°C) or higher and must remain 40°F (5°C) or higher for a minimum of 24 hours. Provide temporary protection to protect the wall system from damage until permanent flashings, caps and sealants are installed. Store materials in a dry place, within prescribed temperature limits and out of direct sunlight. Working and drying times are based upon normal room temperature conditions and will vary with temperature and humidity.
Preparation - The substrate must be approved by Master Wall Inc., clean, dry, structurally sound and free of efflorescence, oil, grease, form release agents and curing compounds or anything that would affect bond. Painted surfaces are not acceptable and must be removed or metal lath applied. All sheathed applications must receive a minimum of 2-layers code-approved asphalt felt or equivalent.
Prepare smooth or non-absorbent solid substrates by one of the following methods or a combination; Sandblasting, chipping or acid etching, A dash-bond coat applied forcefully, Bonding compounds such as Master Wall Stucco Ad Liquid or Primer 57, Furred or self-furring metal plaster bases as per ASTM C1063.
Mixing - Each bag of OCS is mixed with 200 lbs (90.7 kg) of sand aggregate (ASTM C897 or ASTM C144) and clean, potable water (200 lbs is roughly 2.5 cubic feet (0.07 cubic meters) of clean, damp-loose sand or 2-3/4 Master Wall pails, filled). Using a clean mixer, first add 1/2 to 2/3 the water required, 1/2 the sand, 1 bag OCS, then the rest of the sand and water to achieve the desired workability. Mix materials for 3 to 5 minutes after all materials are in the mixer. Total water content can vary between 4 to 6.5 gallons (15-24.5L). Stucco Ad-Liquid may also be used instead of an equal amount of water (up to 5 gallons, 18.9L). See system data sheet for specific levels required for increased warranties.
Tempering-The mixed stucco can be re-tempered one time within 1 hour. Material older than 1-1/2 hours should be discarded.
Application
Apply OCS by hand or machine to a minimum nominal thickness of 3/8 (9.5 mm) for masonry, concrete and stucco applications. Measure stucco coat thickness from the back of the metal plaster base not including ribs and dimples or from the face of solid substrates exclusive of texture variations. Where plaster abuts dissimilar materials, provide for separation. To avoid cold joints the application should stop at corner angles, rustications, openings and control joints.
On metal plaster bases, apply OCS with sufficient material and pressure to totally embed the metal base. A second pass may be required to obtain the minimum thickness of 3/8 (9.5 mm), 1/2 (12.7 mm) suggested for better lath coverage. Rod or straight edge the surface to provide an even base for the Superior Finish.
On solid plaster bases, dampen high-suction bases with clean water or Stucco Ad-Liquid prior to the application of OCS. Rod or straight edge the surface to provide an even base for the Superior Finish.
Curing-Moist cure using fogging, plastic films or other method acceptable to the design professional for 48-72 hours. Mixes with Stucco Ad-Liquid do not need moist curing. Allow to fully cure until clean, dry and hard before finishing-typically 7-14 days. See Master Wall Technical Bulletins and data sheets for additional curing, drying and application recommendations.
Clean Up-Tools and equipment can be cleaned with soapy water while the OCS mixture is still wet.
