Description:
Western One-Pass Plasteris a factory-sanded, fiber-reinforced, premium blended, modified portland cement plaster designed for both one-coat and conventional stucco systems. The product requires only the addition of clean potable water at the jobsite. Unlike traditional field-mixed scratch and brown applications, Western One-Pass Plaster is formulated to be applied in thicknesses ranging from 3/8 inch to 7/8 inch in accordance with ER-382 and applicable building codes. 

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When used as a conventional plaster, it may be applied in separate lifts or built to full allowable thickness in a single application where permitted. 

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By eliminating field batching variables, every bag, every batch and every wall are produced with consistent performance characteristics. Western One-Pass is blended in a pump-grade version with excellent flow that does not require additional additives (Hi-Flow).

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Product Uses:
Western One-Pass Plaster is designed for exterior vertical wall applications in commercial, custom residential and residential construction. It may be used in one-coat stucco assemblies, conventional scratch and brown systems, and monolithic plaster applications where permitted by code and evaluation report. Western One-Pass is compatible with fire-resistance-rated and NFPA 285 compliant assemblies constructed in accordance with IAPMO UES ER-382.

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Packaging:

• Western One-Pass Plaster is packaged in 80 lb / 36.29 kg bags.

• 42 bags per pallet.

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Features and Performance:
• Engineered for application from 3/8" to 7/8" thickness.
• Suitable for one-coat and conventional stucco assemblies.
• Premium fiber reinforced formulation for improved crack resistance.
• Factory controlled sand gradation for consistent strength and workability.
• Evaluated under IAPMO UES ER-382 for code recognition.

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Mixing:
Western One-Pass Plaster accurately mixed with water is critical to maximizing product performance. Each 80 lb bag shall be mixed with 1.25 to 1.5 gallons of clean potable water. One gallon of clean potable water shall be added to the mixer before the addition of each bag. The remaining water may be introduced gradually during mixing to achieve proper workability. Mixing time in a mechanical mixer shall be two (2) to three (3) minutes per bag minimum. Care shall be taken when continuous batching to ensure each bag receives the minimum mixing time.

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Coverage:
• Approximately 2.75 sq. yds. / 2.3 sq. meters @ (3/8") thickness
• Approximately 2.0 sq. yds. / 1.7 sq. meters @ (1/2") thickness
• Approximately 1.37 sq. yds. / 1.15 sq. meters @ (3/4") thickness
• Approximately 1.17 sq. yds. / 0.98 sq. meters @ (7/8") thickness

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Coverage will vary depending on substrate conditions and application method.

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Application:
Western One-Pass Plaster may be applied by approved applicators using hand or plaster pump methods.
Application methods, acceptable substrates and total applied thickness shall comply with ASTM C926, ASTM C1063, ER-382 and applicable building codes. Minimum thickness over approved lath assemblies shall be three-eighths (3/8") of an inch. Maximum thickness may be built to seven-eighths (7/8") in accordance with ER-382 and approved lath configurations. When applied in conventional assemblies, the coating shall be properly rodded, darbyed and densified. Hard floating is required to promote surface densification. Overworking of the material shall be avoided.

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Curing:
The product requires a minimum of forty-eight (48) hours moist curing.  Environmental conditions such as heat, wind and low humidity will require additional curing.

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Finishing:
A variety of finishes such as Western Exterior Stucco, standard acrylic paint and Premium Acrylic Finish (PAF) may be applied over Western One-Pass Plaster. The recommendations of the finish coat manufacturer shall be followed regarding base coat preparation, bonding, application and curing of their product.

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Limitations:
Do not apply when surface or ambient temperatures are at or below 40°F / 4.4°C or above 100°F / 38°C. Do not apply to surfaces that are contaminated with bond breakers, oils or other matter that may affect the performance of the product. Do not apply if conditions are expected to be above or below the specified temperature range within 24 hours of application. Do not add additional ingredients without specific written approval from an authorized manufacturer of Western Blended Products.

 

Storage:
Western One-Pass Plaster shall be kept indoors or if stored outdoors, shall be adequately covered to keep dry and be stored off the ground. 

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Applicable Standards, Specifications and Codes:
IAPMO UES ER-382
2024, 2021, 2018 & 2015 International Building Code (IBC).
2024, 2021, 2018 & 2015 International Residential Code (IRC).
2025 & 2022 California Building Code (CBC).
2025 & 2022 California Residential Code (CBC).
2025 California Wildland-Urban Interface Code.
2023 Florida Building Code (FBC Building).
2023 Florida Building Code (FBC Residential).
ASTM C926 — Application of Portland Cement-Based Plaster
ASTM C1063 — Installation of Lathing and Furring
ASTM C150 — Portland Cement

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Conditions of Use and Limited Warranty:

Specifications for this product are based on optimal environmental conditions (70°F ambient temperature with 50% humidity) for preparation, mixing, application and curing. Specification parameters may vary as environmental conditions change. Consult the product’s Safety Data Sheet or GHS Section located on the product package for hazard identification and first aid measures. KEEP OUT OF REACH OF CHILDREN.

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Western Blended Products (WBP) warrants that its products are of merchantable quality and suitable for the general purpose for which they are intended when applied in accordance with WBP instructions. The manufacturers of WBP products do not warrant the products to be suitable for any purpose or use other than that for which they are intended. Liability under this warranty is limited to supplying new material without charge or, at the option of the manufacturer of the WBP product, refunding the purchase price. In the event of a claim under this warranty, written notice must be provided to the originating plant of the WBP product at the address shown herein. This limited warranty is issued and accepted in lieu of all other express warranties and expressly excludes liability for consequential damages. Some states do not allow the exclusion or limitation of incidental or consequential damages, or limitations on how long an implied warranty lasts; therefore, the above limitations or exclusions may not apply.