Merlex Stucco Keeping it Premium since 1963


Exterior Stucco

  Polymer-modified base coat and anti-fracture membrane for smooth-troweled finishes
  Hand applied with embedded mesh
  BASEX Merlex BASEX is specifically designed for application over brown coat where smooth-troweled finishes are used (such as Santa Barbara Finish). When mesh is embedded in BASEX, cracking is reduced significantly, which allows for higher-quality smooth-troweled finishes. BASEX contains a high percentage of polymer for flexibility, microscopic fibers for crack-resistance, and proprietary additives for workability and working time. The product has suction to ensure good bond between the finish plaster and base coat. BASEX can also be used on rescrubs directly over structurally sound existing plaster, eliminating the need for sandblasting.
  • Provides crack-resistance and impact-resistance when used with mesh
  • Withstands cracks in basecoat up to 0.04 inches without cracking through the finish coat1
  • Ideal for new construction and rescrubs
  • Eliminates need for sandblasting old stucco
  • Contains 10% post-industrial recycled content
  • Ready to use, with all ingredients in the bag
  • An economical alternative to EIFS base coats
  • Available in #20, #30, and #60, and #90 grit
  • Provides a durable, extremely hard, water-resistant base coat
Textures & Substrates
  BASEX is suitable for application over standard Portland cement brown coat, concrete masonry units, existing stucco, and brick. For smoother finish coats, #30 or #60 should be used.
Components & Storage
  Merlex BASEX is packaged in 90 lb bags, 30 bags per pallet. Product must be kept dry at all times.
  Coverage depends on thickness of mesh used. One 90 lb sack will cover approximately 80 to 100 square feet at 1/8" thickness over 4 ounce mesh.

Merlex BASEX should be mixed with clean water to the consistency of exterior Portland cement brown coat. This can be accomplished one bag at a time in a bucket with a suitable drill and mixing paddle, or in a mechanical mixer. Do not entrain air by overmixing or using excessive mixer speed. After mixing, allow material to sit for approximately 5 minutes, and then re-temper by mixing for a short period of time.


Merlex BASEX must be used in conjunction with alkali-resistant mesh (4.0 ounce/square yard mesh is available from your Merlex distributor) to achieve its full crack-resistance. Apply 1/8" of BASEX over the brown coat and then immediately embed mesh in BASEX. Ensure that no wrinkles occur in mesh and no mesh is visible through BASEX. Float the BASEX with a sponge float in order to achieve optimal results when the finish plaster is applied.

Allow BASEX to dry at least 24 hours. To ensure bond, mix Merlex Acrylex acrylic admixture into the finish coat plaster at a ratio of 1/3 gallon per 90 lb. sack of stucco. As an alternative (optional), Merlex Superhold EVA bonder may be applied directly to BASEX prior to application of finish plaster. Note that use of a surface bonder such as Superhold will give the user longer working time on the application of the finish coat and may require more time for finish trowelling. For best results, use Superhold over the BASEX and Acrylex in the finish plaster mix.

  Immediately clean all tools and mixing equipment with water after use.
  Merlex BASEX should not be expected to eliminate all cracking, and is most effective for controlling one-time minor structural cracks, including door and window cracks. BASEX should not be used when temperature exceeds 110 F (43 C) or will fall below 40 F (4 C) within 48 hours of application.
  Merlex BASEX is warranted to perform in accordance with the product specification when used according to application instructions. This warranty is limited to and shall not exceed the total amount paid by the buyer for the product. In no event will Merlex Stucco, Inc. be liable for loss of profits, labor, or special or consequential damages in respect to any claim. The foregoing warranties are in lieu of all other warranties express or implied including those concerning fitness for a particular use.
Environmental & Safety
  Merlex BASEX contains Portland cement and is alkaline on contact with water.  May be irritating to eyes and skin.  Wear appropriate dust, skin, and eye protection.  In case of eye contact, flush immediately with water, and consult a physician.  Wash hands with soap and water after use and before eating.  Keep out of reach of children.
Material Standards

Portland cement: UBC 24-3
Silica sand: ASTM C-144


1 Based on ASTM C-307 average test results from third-party laboratory.  Test results available upon request.

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