Replacing Damaged Pigmented Structural Glass Panels

Procedure code:
National Capitol Region Specifications
Doors and Windows
Last Modified:




    A.   This procedure includes guidance on selectively replacing
         all cracked and broken structural glass panels with new
         to match original adjacent structural glass panels.  It
         also includes information on regrouting open or
         deteriorated joints.

    B.   See also 08810-01-R, 08810-01-S and 08810-03-R for
         additional guidance on the preservation of pigmented
         structural glass.

    C.   Safety Precautions:

         1.   Comply with municipal and Federal regulations
              governing the cleaning, chemical waste disposal,
              scaffolding protection to adjacent properties and

         2.   Refer to Federal Government Specification Section
              01546, Health and Safety, and comply with all the
              section requirements.

    D.   See 01100-07-S for general project guidelines to be
         reviewed along with this procedure.  These guidelines
         cover the following sections:

         1.   Safety Precautions

         2.   Historic Structures Precautions

         3.   Submittals

         4.   Quality Assurance

         5.   Delivery, Storage and Handling

         6.   Project/Site Conditions

         7.   Sequencing and Scheduling

         8.   General Protection (Surface and Surrounding)

         These guidelines should be reviewed prior to performing
         this procedure and should be followed, when applicable,
         along with recommendations from the Regional Historic
         Preservation Officer (RHPO).


    A.   Work Description: Prior to commencing the work, the
         Contractor shall submit to the Contracting Officer's
         representative a written description of the entire
         methods and procedures proposed for all the work to be
         carried out to the structural glass and including, but
         not limited to, preparation, cutting out, procedure,
         regrouting, replacement and, bedding specifications and
         ratios and content of materials.

         1.   No frozen materials are to be used. Protect finish
              against premature drying out caused by sunlight and

    B.   Work Description: Prior to commencing the cleaning
         operations, the Contractor shall submit to the
         Contracting Officer's representative a written
         description of the entire methods and procedures proposed
         for cleaning the structural glass including, but not
         limited to, methods of grinding, sanding and polishing,
         drying times and methods, method of sealing and proposed
         protection and handling procedures.


    A.   Performance Requirements:

         1.   The general objective for structural glass repair
              and replacement is to match the pigment and all
              aspects of the structural glass with the original
              in all respects.

         2.   The general objective of structural glass cleaning
              is to remove dirt, grime and coatings from the
              surface without damaging the underlying material
              and to give all the structural glass a clean
              uniform appearance without blotches.


    A.   Product Data: Submit manufacturer's product and technical
         literature and instructions including all recommendations
         for their application and use to the Contracting
         Officer's representative for all cleaning and patching
         materials. Include test reports and certifications,
         substantiating that products comply with requirements.


    A.   Qualifications: The work of this section shall be
         performed by a firm possessing a minimum of three (3)
         years of specialized experience in the restoration and
         cleaning of historic architectural structural glass,
         similar to work required in this project. The Contractor
         shall submit to the Contracting Officer's representative
         references of previous work, justifying the firm's
         experience. The Contracting Officer's representative
         reserves the right to approve or disapprove the use of
         the Contractor contingent upon the firm's experience.

         1.   NOTE: The quality of the work is highly dependent
              on the competence of the Contractor because
              matching is a specialized skill.

         2.   In the event that the Contractor wishes to modify
              any methods specified in this section, he shall
              submit his proposal in writing for consideration
              and review. The Contracting Officer's
              representative will have the right to ask for
              control samples before final approval. Any such
              modifications or changes shall be at no additional
              cost to the Government.

    B.   Regulatory Requirements: Comply with municipal and
         Federal regulations governing all work included in this
         section and including, but not limited to, cleaning,
         waste disposal and protection to adjacent properties.

    C.   Field Samples: Sample panels for cleaning and replacement
         of structural glass shall be prepared for review and
         shall establish a standard for all structural glass work.
         The locations and types of control samples are to be
         indicated on a plan, with a photograph of each control
         sample to be submitted to the Contracting Officer's
         representative. No work shall commence until a written
         review of the control samples has been obtained from the
         Contracting Officer's representative.

         1.   The Contractor shall clean sample structural glass
              panels of each color of structural glass, for
              review by the Contracting Officer's representative.
              Locations of sample panels to be selected by the
              Contracting Officer's representative.

         2.   The Contractor shall prepare an 8 linear foot
              sample showing the regrouting of joints between the
              structural glass panels. Samples are to be prepared
              for each structural glass color. The location of
              sample panels are to be selected by the Contracting
              Officer's representative. All samples are to be
              reviewed and approved in writing by the Contracting
              Officer's representative.

         3.   The Contractor shall prepare a sample panel of
              replacement structural glass. The sample panel
              should be made to match the original structural
              glass in all respects.

         4.   All the control samples are to be located on floor
              plans and clearly numbered in the field. The
              approved samples are to be identified on separate
              plans and are subject to review and approval in
              writing by the Contracting Officer's

         5.   All procedures and methods for sample preparations
              are to be submitted by the Contractor to the
              Contracting Officer's representative for review and
              written approval.

         6.   Retain and protect the approved samples throughout
              the contract. The approved samples shall be the
              sole responsibility of the Contractor.

         7.   Any work considered by the Contracting Officer's
              representative to be of a lower grade than the
              reviewed samples, in any respect, will be the sole
              responsibility of the Contractor to replace.


    A.   Packing and Shipping: Deliver materials to the site in
         the manufacturer's original and unopened containers and
         packaging, bearing labels as to the type of material,
         brand name and manufacturer's name. Delivered materials
         shall be identical to tested materials.

    B.   Storage and Protection:  Store materials off the ground
         in a dry, clean location. Remove materials which are
         damaged or otherwise not suitable for use from the job


    A.   Environmental Requirements: Improper use of chemicals may
         constitute a health hazard. Refer to manufacturer's
         Material Safety Data Sheets for hazard data, special
         protection, for use and precautions to be taken in
         handling and storage. Comply with manufacturer's
         recommendations for proper use of chemicals.

    B.   Existing Conditions:

         1.   The Contractor is responsible to take all necessary
              precautions and measure to protect all surrounding
              materials from damage that might be incurred during
              the structural glass restoration work described in
              this outline specification. Any damage caused by
              the Contractor to other materials is unacceptable
              and shall be repaired or replaced by the Contractor
              to the satisfaction of the Contracting Officer's
              representative, at no cost to the Government.

         2.   The Contractor is responsible for providing all
              protection necessary to adjacent materials.

         3.   The Contractor shall provide for all site
              attendance and for all inspections of structural
              glass work and materials, as required by the
              Contracting Officer's representative.



    A.   Pilkington,

    B.   PPG Industries (formerly Pittsburgh Plate Glass),

    C.  General Electric,

     D.   Vitrolite Specialist, www, 


    A.   Water: Potable, non-staining and free of oils, acids,
         alkalis and organic matter.

    B.   Pigments: Pure mineral earth pigments resistant to
         alkalis and non-fading. Suitable colors are to be
         selected to match existing in all respects, to the
         standard of the approved samples.

    C.   Cleaning Agents - Structural Glass: Application for
         removal of soil and grease build-up. Use a mild solution
         of water mixed with potable ammonia.

    D.   Cleaning Agent - Surface Masonry: Application for removal
         of soot and soil build-up. Use a light detergent or a
         mild chemical wash.

    E.   Solvents such as methyl ethyl ketone, methyl isobutyl
         ketone or acetone.

         Methyl Ethyl Ketone:

         1.   Other chemical or common names include 2-butanone;

         2.   Potential Hazards:  TOXIC AND FLAMMABLE.

         3.   Available from chemical supply house, hardware
              store or paint store.

         Methyl Isobutyl Ketone:

         1.   Other chemical or common names include Asymmetric
              ethyl methyl acetone; 3-methyl-2-pentanone;
              Secondary butylmethyl ketone; MIBK*.

         2.   Potential Hazards:  TOXIC AND FLAMMABLE.

         3.   Available from chemical supply house, hardware
              store or paint store.

         Acetone (C3H6O):

         1.   A volatile fragrant flammable liquid ketone used
              chiefly as a solvent and in organic synthesis.

         2.   Other chemical or common names include Dimethyl
              ketone; Propanone

         3.   Potential Hazards:  VOLATILE AND FLAMMABLE SOLVENT

         4.   Available from chemical supply house or hardware

    F.   Asphalt-Based Mastic Adhesive: Application for attachment
         of glass panels to masonry substrate.

    G.   1/16" Adhesive Cork Tape: Applied to the horizontal edges
         of the glass panels to provide separation for the glass

    H.   Joint Cement or Caulking Compound: Application for
         filling narrow 1/16" to 1/32" joints between structural

         1.   Use a joint compound with an integrated watertight
              surface, capable of being used int he narrow joints
              described above.

    I.   Replacement Glass Panels.  Alternative products may be
         used with RHPO approval.  Contact manufacturers and/or supplies for 
         current product inventory; examples of product names include "Vitrolux", "Spandrelite", 
         "Sheet Plastic", or approved equal.

         1.   Alternative products should be a good color and
              finish match to the existing original structural
              glass to the satisfaction of the Contracting
              Officer's representative.

    J.   Clean, soft cloths


    A.   Crook neck polyethylene laboratory squeeze bottle or
         large syringe without needle.

    B.   Piano wire

    C.   Joint tools

    D.   Soft bristle brushes



    A.   Protection: Prior to commencing the cleaning operations,
         the Contractor shall submit to the Contracting Officer's
         representative for review a written description of
         proposed materials and methods of protection for
         preventing damage to adjacent materials and the building
         interior during the cleaning of the structural glass.

    B.   Surface Preparation: All bonds, joints, patterns, etc.,
         are to be maintained to the original layout. Jointing
         strips are only to be used in previous locations unless
         otherwise noted.

         1.   Removal: Where existing glass panels are damaged
              and broken, they should be carefully removed.
              Soften the mastic by injecting solvent behind the
              panel using a squeeze bottle or syringe.  Separate
              the panel from the wall using a taut piano wire to
              cut through the softened mastic. Remove all
              existing asphalt-based mastic adhesive from the

         2.   Existing Substrate: Clean the existing substrate
              thoroughly with a light detergent or mild chemical
              wash to remove all built-up soiling. Allow
              substrate to dry out fully prior to installation of
              structural glass panels.

         3.   Rake out all loose joint cement. Wash all joints
              with a soft bristle brush and water. Allow all
              joints to dry fully prior to regrouting.

         4.   Repair minor hairline cracks.  See 08810-01-R for


    A.   Clean substrate with a light detergent or mild chemical
         wash. Allow to dry.

    B.   Clean old structural glass to be reinstalled.  Remove
         soil and grease build-up and all old asphalt-based

    C.   Install new structural glass panel: Apply daubs of
         asphalt-based mastic adhesive to the glass and then
         attach directly to the substrate, leaving a cavity of
         3/8" between the glass and substrate. The temperature
         should not be less than 40 degrees F. The daubs of asphalt mastic
         should be 2" to 3" in diameter and cover 50% of the glass
         panel area. Asphalt-based mastic is recommended to cover
         a 3" perimeter width of the glass panel and around all
         holes and openings.

         1.   Use a 3" square 3" leg 18 gauge stainless steel
              angle spaced 3'-0" (maximum) on center in the
              vertical dimension and 2 angles per structural glass panel
              in the horizontal direction.

         2.   To be installed to provide support for the
              structural glass panel.

         3.   Push the glass panel onto the substrate truing it
              for level and plumb and maintaining the necessary

         4.   Glass seams: All glass seams and abutments to be
              protected or separated. Apply 1/16" thick adhesive
              cork tape along the horizontal edges of the
              structural glass panels and recessed 1/8" from the
              front face of the panel.

    D.   Grout the joints:

         1.   Rake out all loose joint cement.

         2.   Blend the caulking compound to match the color of
              the original caulking by adding pigment.

         3.   Fill the joints neatly and avoid spreading the
              caulking compound over the adjacent structural
              glass panels in order to minimize necessary clean

         4.   When the material has hardened, remove excess
              caulking compound using the manufacturer's
              specified solvent. This should be applied sparingly
              to a clean rag and the glass wiped clean and dry.

                         END OF SECTION

Last Reviewed 2015-06-12