LARRYN SMERLING | DS 224 | FALL 2020
MOLDING
PLASTER
Pragma Estudio
Source & Production
Plasters malleable nature allows it to be formed into virtually any shape of texture. Traditionally the material is used to apply ornate details onto ceilings, walls, and accent pieces. Gypsum board replaced plaster for wall use, making plaster more common for molding. Plaster is a mixture of Lime, gypsum, water and sand.
Plaster is a material that begins as liquid and is set and dried into place. Because of the initial state of the material it can have an array of applications and textures. The benefits of using plaster is that it is durable and Fire resistant. One down side of the material is that it is fairly labor extensive to achieve the wanted results.
Characteristics
Product Application
Plaster is a versatile substance; it takes an experienced person to skilled in plaster work to do quality molding. The most common use for plaster in interiors is in crown molding. The molding/ cornice wraps around a room greatly altering the style of the space from the chosen design.
Maintenance:
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crown molding
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trim
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decorative finishes
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statues
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ceiling/ wall details & textures
Maintenance Requirements
Sealed plaster can be easier to clean because it is less porous, but the sealer adds potential complications to the cleaning process. Unsealed plaster is difficult to clean without causing damage. Clean sealed plaster with a swab dampened with water or white spirit. Dust can be removed with a soft cloth or brush. Plaster is mildly soluble in water and is vulnerable to damage from cleaning products and abrasives, which will remove the surface layer. Cleaning should minimize the use of liquid. Stains absorbed deep into plaster will be challenging to remove.
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Organizations:
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Environmental Impact
Gypsum plaster waste (GPW) represents a large portion of the total construction/demolition wastes(contaminating soil and water resources). The possibility of recycling GPW is unknown, if the recycling process affects rehydrated products/ how often it can be recycled without changing its characteristics. The recycling process does not alter the gypsum plaster chemical composition, similar to the commercial gypsum plaster. Physical properties are changed: bulk density diminished, setting times were shorter due to the change in the grain size with the recycling process. The mechanical performance was good with similar results at longer ages. GPW recyclability has excellent potential to be a successful industrial solution, and it allows the production of new reusable products with less negative environmental impacts.
Young Projects
Foster Reeve
Testing & Building requirements
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2511.3 Grounds
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Where installed, grounds shall ensure the minimum thickness of plaster as set forth in ASTM C842 and ASTM C926. Plaster thickness shall be measured from the face of lath and other bases.
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2511.2 Limitations
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Plaster shall not be applied directly to fiber insulation board. Cement plaster shall not be applied directly to gypsum lath or gypsum plaster except as specified in Sections 2510.5.1 and 2510.5.2.
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2511.1 General
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Plastering gypsum plaster or cement plaster shall be not less than three coats where applied over metal lath or wire fabric lath and not less than two coats where applied over other bases permitted by this chapter.
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Exception: Gypsum veneer plaster and cement plaster specifically designed and approved for one-coat applications.
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Gypsum casting and molding plasterASTM C59
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Gypsum Keene's cementASTM C61
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Gypsum plasterASTM C28
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Gypsum veneer plasterASTM C587
Gypsum board and gypsum panel productsGA-216; ASTM C840
Gypsum sheathing and gypsum panel productsASTM C1280
Gypsum veneer baseASTM C844
Interior lathing and furringASTM C841
Steel framing for gypsum board and gypsum panel productsASTM C754; C1007
Kennedy Keegan
Plaster sculpture:
Abstracted view of plaster application
Standards
ASTM international
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C1467/C1467M-00(2016) Standard Specification for the Installation of Molded Glass Fiber Reinforced Gypsum Parts
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C1787-14(2019) Standard Specification for Installation of Non Metallic Plaster Bases (Lath) Used with Portland Cement Based Plaster in Vertical Wall Applications
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C1063-20 Standard Specification for Installation of Lathing and Furring to Receive Interior and Exterior Portland Cement-Based Plaster
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C843-17 Standard Specification for Application of Gypsum Veneer Plaster
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C842-05(2015) Standard Specification for Application of Interior Gypsum Plaster
Sources
East Pyongyang Grand Theatre, Pyongyang, 1989