Temporary Patching Of Chips And Cracks In Window Glazing

PART 1–GENERAL

1.01 SUMMARY

1. This procedure includes guidance on temporarily repairing chipped or cracked glass by patching with an adhesive.
2. 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”.
3. 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

1. 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

1. 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

1. Glass Adhesives

2.02 MATERIALS

1. 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
2. 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.

   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.

   -OR-

3. Acetone (C3H6O):
   1. A volatile fragrant flammable liquid ketone used chiefly as a solvent and in organic synthesis and found abnormally in urine.
   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 store.

2.03 EQUIPMENT

1. Syringe or eye dropper
2. Heavy gloves, goggles and other protective gear
3. No. 6 natural fiber paint brush
4. Scalpel

PART 3–EXECUTION

3.01 EXAMINATION

1. 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

1. Remove dust/dirt from the crack by gently blowing a stream of air into the crack.
2. Flush the crack with a solvent applied by syringe or eye dropper.
3. Hold the cracked glass together with Scotch tape placed on one side of the crack.
4. Apply adhesive with a number 6 natural fiber paint brush.
5. Allow to dry; remove scotch tape and excess adhesive with a scalpel.
6. Normal glass cleaning operations should not affect the bond.