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


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.

Last Reviewed: 2017-08-13