Plaster Weld

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$44.99 - $169.95
14.00 LBS
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Product Overview



Plaster-Weld® bonds new plaster to any clean, structurally sound, interior surface. The original chemical plaster bonding agent is a patented formulation incorporating polyvinyl acetate homopolymer. DESIGNED FOR INTERIOR USE ONLY, the high performance bonding of one-coat finish plaster and/or two and three coat work to concrete ceilings, walls, columns, beams, and other structurally sound surfaces. Plaster-Weld® prepares the surface to allow you to plaster directly to concrete over electric radiant heat cable, and to bond cement mortar beds to smooth concrete for installation of rigid foam insulation. Concrete, brick, block, glass, ceramic tile, wallboard, metals (e.g. sheet lead in x-ray rooms) and marble are suitable sound surfaces, structurally. Plaster-Weld® can be used over paints having oil, rubber or vinyl bases, and over silicone-treated surfaces, as well as latex paints.

Plaster Weld Data Sheet in PDF

Plaster Weld MSDS in PDF

Plaster Weld Leed Information in PDF


Plaster-Weld Performance Properties

Data obtained from tests conducted periodically by leading independent laboratories. Test reports are available upon request.

  • Tensile Bond Strength:
    ASTM C-631 (pulling apart bonded cement briquet halves). In all cases failure occurred in the cementitious material, not in the bond. 385 psi. Avg. 28 days.
  • Temperature Range:
    ASTM C-109 (specimens brought to 35 degrees F for 1 hr., then to 310 degrees F for 2 hrs). No bond failure. Shear tests 400 psi. Avg.
  • Freeze-Thaw Stability:
    5 cycles freeze (-10 degrees F and thaw). Freeze-thaw stable.
  • Toxicity:
    Enclosed mice exposed to 30 cc volatized bonding agent for 1 hr. Non-toxic, no ill effects after 7 days.
  • Fire Resistance:
    ASTM E-119 (bonded assembly). Passed 2 hr. Fire Test 1800 degrees F and 1 hr. Hose Stream Test.
  • Flammability:
    Meets MIL-B-19235C, non-flammable.
  • Acid Resistance:
    1″ concrete slabs bonded to 1/2″ gypsum plaster subjected to seepage of strong detergents and synthetic urine for 10 hrs. a day. No bond failure after 25 consecutive days. Also unaffected by alkalinity of cement.
  • Life Expectancy:
    Lab tested and field proven. Non-deteriorating bond

Plaster Weld Guide Specifications: Divisions 3 & 9

Divisions 3 & 9

1. General

  • 1.1 Product Handling
    1. Deliver Plaster-Weld® to job in original container with seals unbroken and use without reducing.
    2. Materials Storage: Protect Plaster-Weld® from freezing.
  • 1.2 Environmental Conditions
    1. Air and surface temperatures must be above freezing during application ofPlaster-Weld®.
  • 1.3 Protection
    1. Plaster-WeldProtect adjacent finish surfaces with masking tape, soap powder emulsion, or a commercial product, specially formulated for protective use in plastering.

2. Products

  • 2.1 Materials
    1. Bonding Agent: Plaster-Weld®, Larsen Products Corp., Jessup, Maryland


  • 3.1 Surface Preparation
    1. Surfaces to receive Plaster-Weld®MUST BE STRUCTURALLY SOUND AND CLEAN, free from loose material, dust, dirt, oil, grease, wax, loose paint, mildew, rust, laitance, or efflorescence. Form release agents, curing compounds, hardeners, and sealers must be compatible withPlaster-Weld®.
  • 3.2 Installation
    1. Application of bonding agent: Apply Plaster-Weld® uniformly using brush roller, or spray to form a continuous pink film over the entire surface. Allow to dry one hour. (NOTE: Painted surfaces must be sound, washable and firmly adhered to the substrate. Glossy painted surfaces should be dulled with an abrasive. Wait 60 days before applying bonding agent over newly painted surfaces. Application of wallpaper to newly bonded plastered surfaces should be delayed 90 days.
    2. Inspection of bonding agent: Prior to applying plaster, inspect bonding agent application to assure a continuous pink film over the entire bonding surface. Reapply Plaster-Weld® over areas not satisfactorily covered.
      • 3.2.1 Application One-Coat Plaster
        1. Apply a white skim coat of plaster 1/16 to 3/16 inch thick overPlaster-Weld® direct to concrete ceilings and other structural surfaces as shown and specified (the mixing, application and finishing of white coat shall be as specified for regular white finish coat). At contractor’s option, Plaster-Weld® and a white skim coat of plaster may be applied on interior ceilings, walls, beams and columns in place of smooth or rubbed concrete surfaces as shown or specified. (NOTE: Plastering can begin immediately as soon as bonding agent is dry to the touch [allow 1 hour] or delayed a week to 10 days with no effect on bond.)
      • 3.2.2 Application of Two and Three Coat Plaster
        1. Apply scratch coat a minimum of 3/8 inch thick over Plater-Weld®to surfaces as shown and specified. Allow to dry 24 hours (follow with two and three coat applications). (NOTE: Minimum drying time of 24 hours between coats is important to prevent moisture in second coat from penetrating the scratch coat and flooding the bond film.)
      • 3.2.3 Application of Plaster over Electric Heating Cable:
        • Contact Larsen Products for Guide Specifications.
      • 3.2.4 Patch Plaster Over Plaster-Weld® following work of other trades