Plaster Flex is an ultra-fine version of our Superior Finish line. Suitable for interior or exterior use it can be used to create a textured or ultra-smooth surface using a variety of techniques and can even be applied over existing interior plaster work.

Interior Uses

Levels and skim coats existing plaster or drywall surfaces
Adheres to most paints
Bridges Minor Cracking
Encapsulates Lead Paint
No messy mixing like traditional plaster finishes

Exterior Uses

Final color coat over Master Wall® base coats, One Coat Stucco or traditional stucco
Detail work: cornices, quoins, etc.

Plaster Flex is available in standard or custom colors, Plaster Flex may be applied over Master Wall Base Coats or stuccos or interior surfaces. Plaster Flex is available in five-gallon (19L) pails and is typically troweled onto the wall surface with a stainless steel trowel.


  • Varies with technique, thin 1-coat application is 300 square feet (28 square meters) per pail

*Coverages are estimated and vary

Weight: 65 lbs (29.5kg)

Working Time: 1/4 hour under normal room temperature and humidity.

Drying Time: 8-12 hours to set, 48-72 hours to dry under normal room temperature and humidity.

Application/Storage Temperatures: 40°F (5°C) to 110°F (43°C)

Shelf Life: 2 years under normal conditions.

Approved Substrates

  • Master Wall® Base Coats
    Prepared & Base Coated Surfaces of:
    Interior Drywall made ready for paint
    Others approved in writing

Application Procedure

Job Conditions – Air and substrate temperature for application of Plaster Flex 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 within prescribed temperature limits and out of direct sunlight. High temperatures will reduce working times, Low temperatures and/or high humidity will extend working, set and dry times.

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. Concrete and surfaces should cure for a minimum of 28 days. Stucco should be cured until clean, dry and hard—typically 7-14 days.

Interior Drywall– Prime surfaces with Sanded Primecoat primer prior to finishing. Bond test prior to application on previously painted surfaces.

Base Coats – Must be flat, dry hard, and free of efflorescence. Master Wall® base coats must cure a minimum of 12 hours before application of Superior Finish. Substrates of brick, masonry or concrete should be leveled smooth using either Master Wall® base coats or stucco.

Mixing – Thoroughly stir Plaster Flex using a heavy duty 1/2″ (12.7 mm) drill at 400 – 500 rpm and a heavy duty mixing paddle. Small amounts of clean, potable water may be added to obtain a workable consistency. To avoid color variations, add the same amount of water to each pail. Do not exceed 24 ounces (0.7L) of water per pail of finish.

Application — Apply Plaster Flex to match the approved sample texture or effect using the selected tools and techniques. Use stainless steel tools. For best results two thin coats are recommended.

For Professional Results
Apply finish coats away from direct sunlight. Cold joints or color variations can occur if the finish dries too quickly.
Consider priming stucco surfaces with Primecoat to even out finish absorption.
Surfaces exposed to the weather must be sloped (6:12 minimum).
Do not apply to gypsum board or insulation board products.

Clean Up—Tools and equipment can be cleaned with soapy water while the Plaster Flex is still wet.

Information contained in this product data sheet conforms to the standard detail recommendations and specifications for the installation of Master Wall® Inc. products and is presented in good faith. Master Wall® Inc. assumes no liability, expressed or implied as to the architecture, engineering, or workmanship of any project. This information may be concurrent with, or superseded by other applicable documents, such as specifications and details. Contact Master Wall® Inc. for the most current product information.