U.S. General Services Administration
Technical Procedures Disclaimer
Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.
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We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.
TEMPORARY PATCHING OF CHIPS AND CRACKS IN WINDOW GLAZING
PART 1–GENERAL
1.01 SUMMARY
A. This procedure includes guidance on temporarily repairing
chipped or cracked glass by patching with an adhesive.
B. This treatment is simple and inexpensive. Although it
will not remove the crack, it permits the safe use of
cracked window panes until suitable replacements can be
found or where it is desirable to permanently save the
glass in situ. For guidance on replacing glazing, see
08800-01-R “Replacing Broken Glass in Wood and Metal
Windows”.
C. 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).
1.02 SYSTEM DESCRIPTION
A. A window glass is in proper condition when it is set
securely and tightly into the window frame, is properly
caulked, and is not scratched, cracked, or broken.
1.03 SEQUENCING AND SCHEDULING
A. Coordination of Work: The coordination of glass
repairing/replacing with other proposed work on the
windows must be considered. For example, if paint
removal, cleaning, or repairing is anticipated on window
elements (frame, sash, trim, hardware, lintel, sill,
etc.), it is generally better to postpone glazing work
until after the completion of these activities.
PART 2–PRODUCTS
2.01 MANUFACTURERS/SUPPLIERS
A. Glass Adhesives
2.02 MATERIALS
A. Glass adhesive(s): (review current product literature to determine if the product is appropriate, or approved
equal).
1. Should be viscous enough to flow into the cracks
2. Should have a similar refractive index to that of
the glass
3. Should be non-yellowing and reversible
B. Solvents:
NOTE: Chemical products are sometimes sold under a
common name. This usually means that the substance is
not as pure as the same chemical sold under its chemical
name. The grade of purity of common name substances,
however, is usually adequate for stain removal work, and
these products should be purchased when available, as
they tend to be less expensive. Common names are
indicated below by an asterisk (*).
CAUTION: THESE SOLVENTS ARE EXTREMELY FLAMMABLE, AND
THEY IRRITATE THE SKIN. STORE THE SOLVENTS IN FIRE-SAFE
CONTAINERS, AND WEAR RUBBER GLOVES AND GOGGLES WHEN
WORKING WITH THE SOLVENT.
1. Methyl Ketone:
-OR-
2. Methyl Isobutyl Ketone:
a. Other chemical or common names include
Asymmetric ethyl methyl acetone; 3-methyl-2-
pentanone; Secondary butylmethyl ketone;
MIBK*.
b. Potential Hazards: TOXIC AND FLAMMABLE.
c. Available from chemical supply house, hardware
store or paint store.
-OR-
3. Acetone (C3H6O):
a. A volatile fragrant flammable liquid ketone
used chiefly as a solvent and in organic
synthesis and found abnormally in urine.
b. Other chemical or common names include
Dimethyl ketone; Propanone
c. Potential Hazards: VOLATILE AND FLAMMABLE
SOLVENT
d. Available from chemical supply house or
hardware store.
2.03 EQUIPMENT
A. Syringe or eye dropper
B. Heavy gloves, goggles and other protective gear
C. No. 6 natural fiber paint brush
D. Scalpel
PART 3–EXECUTION
3.01 EXAMINATION
A. Before proceeding with steps to repair glazing, first
determine the cause and extent of the problem: Check for
cracked, broken, chipped, or otherwise damaged glass.
3.02 ERECTION/INSTALLATION/APPLICATION
A. Remove dust/dirt from the crack by gently blowing a
stream of air into the crack.
B. Flush the crack with a solvent applied by syringe or eye
dropper.
C. Hold the cracked glass together with Scotch tape placed
on one side of the crack.
D. Apply adhesive with a number 6 natural fiber paint brush.
E. Allow to dry; remove scotch tape and excess adhesive with
a scalpel.
F. Normal glass cleaning operations should not affect the
bond.