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Plastic Cement

A factory-prepared portland cement basecoat for conventional stucco systems. 

Product Information

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Western Plastic Cement is a factory prepared portland cement base coat to which sand and water are added at the job site.  Western Plastic Cement is an integral part of a conventional one-hour stucco assembly.  Western Plastic Cement conforms to ASTM 926 and ASTM C1328


Western Plastic Cement is packaged in 94 lb / 46.63 kg bags.



  • Western Plastic is delivered as a concentrate providing the applicator with a high-quality consistent formula from batch to batch.

  • Western Plastic Cement is an abrasion, impact and water-resistant base coat plaster.


Approximate Coverage (Based on Table 25-F Ratios):
140 sq. ft. / 16.5 sq. yds. – 170 sq. ft. / 18 sq. yds.


Plaster sand for Western Plastic Cement shall comply with ASTM C144 or C897.  Cement to sand ratio shall be per UBC Table 25-F.  Western Gun Cement shall be mixed in a mechanical type mixer.  Add half the potable water and half the sand required for the batch.  While sand and water are mixing add all the bags of Western Plastic Cement required for the batch. Add the full amount of sand required and the minimum amount of water to bring the mix to the proper consistency.  Allow batch to mix for 3 to 5 minutes after all materials are added.


Approximate water usage: 

  • 1 / 3 cement to sand – 2 ¾ to 3 ¼ gallons

  • 1 / 4 cement to sand – 3 ¾ to 4 ¼ gallons


Western Plastic Cement may be applied by hand or machine.  Application methods, acceptable substrates and total applied thickness shall meet the requirements set forth in ASTM C926. Western Plastic Cement may be used in a standard scratch and brown application or by the Alternate Method of Application per UBC 2508.6.  Alternate Method of Application provides a better bond between coats, improves curing and speeds completion times.  Alternate method of application is not suggested for open-frame construction.


The product requires a minimum of forty-eight (48) hours moist curing.  Environmental conditions such a heat, wind and low humidity all require liberal curing.


A variety of finishes such as Western Exterior Stucco, Premium Acrylic Finish E (elastomeric formula), standard acrylic paints or elastomeric coatings may be applied over Western Plastic Cement. The recommendations of the finish coat manufacturer shall be followed regarding base coat preparation, bonding, application and curing of their product.


Do not add accelerator, air entrainment or other admixtures to Western Plastic Cement without written permission from an authorized manufacturer of Western Blended Products. Do not apply when surface or ambient temperatures are at or below 40°F / 4.4°C or above 100°F / 34°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 Western Plastic Cement if conditions are expected to be above or below the specified temperature range within 24 hours of application. Do not add additional ingredients to Western Plastic Cement without specific written approval from an authorized manufacturer of Western Blended Products.


Western Plastic Cement shall be kept indoors or if stored outdoors, shall be adequately covered to keep dry and be stored off the ground.


Applicable Standards, Specifications, and Codes:

  • ASTM C150

  • ASTM C926

  • ASTM 1328,

  • IBC Section 2511 Interior Plaster

  • IBC Section 2512 Exterior Plaster  


Manufacturers of Western Blended Products (WBP) warrant its products to be of merchantable quality and suitable for the general purpose for which they were intended, when applied in accordance with WBP instructions.  Manufacturers of WBP do not warrant its products to be suitable for any purpose or use other than for which they were intended.  Liability under this warranty is limited to supplying new material without charge, or at manufacturers of WBP option, to a refund of the purchase price.  In the event of a claim under this warranty, written notice must be given to the originating plant of the WBP goods at the address shown hereon.  This limited warranty is issued and accepted in lieu of all other expressed 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, so the above limitations and exclusions may not apply to you.  This warranty gives you specific legal rights, and you may also have other rights that vary from state to state.

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