Sampling and Characterizing Plaster

							Sampling and Characterizing
          Plaster

      Roger G. Morse AIA
         Dyanki, Inc.
Sampling and Characterizing
          Plaster
  A New System for Sampling and
   Characterizing Plaster in Three
            Dimensions
 Typical Survey Looks at Plaster
      in Two Dimensions
• Homogeneous areas based on surface
  characteristics
• One type of plaster can have different
  surface characteristics
• Frequently results in large numbers of
  samples
       Example of Homogeneous
      Plasters in Two Dimensions
•   Smooth wall plaster   • Smooth ceiling
•   Lumpy wall plaster    • Lumpy ceiling
•   Wainscot plaster      • Applied decorations
•   Crown molding         • Sandy ceilings
                          • Highly painted
•   Molded plaster          ceilings
•   Sandy wall plaster    • Dashed ceilings
•   Spattered plaster     • High relief molded
•   Knobby plaster          ceilings
       Same Plasters in Three
           Dimensions
• Smooth white finish plaster
• Sandy white finish plaster
• Gray-beige base plaster
   Plaster Classification
                  Initial Inspection


    Collect enough samples to meet AHERA Reg


                    Clean Cores


Examine with Stereo Microscope - Assign Plaster type


     Verify that No. Samples meets AHERA Req.


                 Analyze Samples
               Gravimetric Reduction
              Augmented Point Count


          Analysis Confirms Plaster Type


                  Report Results
           Initial Inspection
• Make an initial determination of likely
  homogeneous plaster types
• Collect a sufficient number of each type to
  meet AHERA requirements for surface
  treatments
  – 1,000 SF – 3 samples
  – 1,000 to 5,000 SF – 5 samples
  – Over 5,000 SF – 7 samples
          Sample Collection
• Core drill connected to HEPA vacuum
• Clean dust from surface of cores in sealed
  cabinet with HEPA local exhaust
Plaster Core
       Evaluate Plaster Cores
• Evaluate with stereo microscope
• Assign plaster type to each layer
• Verify that number of samples meets
  AHERA requirements
    Gross Characteristics of Each
               Layer
•   Layer – (top, middle, bottom)
•   Function – (finish, base, scratch)
•   Gross Color – Munsell Color System
•   Thickness
    Components of Each Layer
• Cement
• Aggregate
• Fiber
             Cement - Type
•   Gypsum
•   Lime
•   Gypsum/Lime
•   Portland Cement
•   Clear Adhesive
              Cement Color
•   White
•   Off White
•   Gray
•   Exact colors from Munsell Color System
            Aggregate - Type
•   Sharp mason’s sand
•   Perlite
•   Vermiculite
•   Mica
•   Washed sand
•   None
             Aggregate Color
•   Colorless
•   Tan
•   Brown
•   Black
•   Red Brown
•   Exact color definition with Munsell Color
    System
                Fiber - Type
•   Hair – cattle or horse
•   Wood fiber
•   Jute
•   Fiberglass
•   Cellulose
•   Suspected of being asbestos
       Engineering Properties
• Plaster strength
• Bond between layers
• Useful for engineering design purposes
       Determine Plaster Type
• Atlas of plasters
• Physical standards
              Analyze Samples
•   PLM
•   Gravimetric Reduction
•   Point Count (1000 points – Chatfield Method)
•   Report concentrations of plaster components
•   Report lime to gypsum ratio
•   Determine if analysis verifies plaster type
    determination
               Plaster Types
•   Job mixed plasters
•   Modern plasters
•   Acoustical plasters
•   Skim coats
•   Plaster substrates
•   Coatings
           Job Mixed Plasters
•   Colored sand plaster
•   White smooth plaster
•   White sand plaster
•   Bond plaster
•   Portland cement plaster (Stucco)
•   Mortar and concrete
            Modern Plasters
•   Perlite aggregate
•   Synthetic fiber reinforcing
•   Gray granular gypsum cement
•   Vermiculite aggregate
           Acoustical Plasters
•   Manufactured products
•   Open porous texture
•   Usually friable
•   Each must be considered separately
•   Frequently contain asbestos
               Skim Coats
• Drywall taping compound
• Clear adhesive
• Fine aggregate (limestone, talc, marble)
• May be between layers of paint
• May not be able to find sufficient samples
  to meet AHERA requirements
• Evaluate separately for each facility
          Plaster Substrates
• Gypsum lath
• Gypsum block
• Gypsum panels (drywall systems)
                Coatings
• Textured coatings
• Heavy hard cementitous coatings
  (Thorocoat)
• May contain tremolite
Roger G. Morse AIA

      Dyanki, Inc.
  504 Snake Hill Road
 Poestenkill, NY 12140