Skip to main content

Historic Preservation - Technical Procedures

Spectitle:

Temporary Patching Of Chips And Cracks In Window Glazing

Procedure code:

0880002R

Source:

Hspg Prepared For Nps - Sero

Division:

Doors And Windows

Section:

Glass & Glazing

Last Modified:

11/19/2014

Details:

Temporary Patching Of Chips And Cracks In Window Glazing



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:

         1.  Conservation Resources International seACME Chemical & Insulation Co., Div. Allied
              www.conservationresources.com Products Corp.
              Epo-Tek  301 
         
         2.  Palmer Opticon Chemical
              www.mirro-mastic.com.O. Box 2445
              Mirro-Mastic         

       
2.02 MATERIALS

    A.   Glass adhesive(s):  (see manufacturers above; 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.

                             END OF SECTION
 


temporary patching of chips and cracks in window glazing, chipped glass, cracked glass