Repairing Small Holes, Nicks, And Minor Imperfections In Cast Iron

REFERENCES

Margot Gayle, David Look, John Waite. Metals in America’s Historic Buildings. Washington,DC: National Park Service, 1995.

L. William Zahner. Architectural Metals. New York: John Wiley & Sons, 1995.

PART 1–GENERAL

1.01 SUMMARY

1. This procedure includes guidance on using epoxy to repair minor surface imperfections in cast iron such as small holes, nicks and minor cracks.

2. 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).

3. For general information on the characteristics, uses and problems associated with cast iron, see 05010-04-S.

PART 2–PRODUCTS

2.01 MATERIALS

1. Epoxy patching compound. Some different types of epoxy include the following:

   NOTE: THE EPOXY PRODUCT SELECTED MUST BE COMPATIBLE WITH THE PAINT CHOSEN.

   1. Auto body putty, such as “Bondo” available from auto body stores or hardware stores.
   2. Resin-impregnated fiberglass (available in mesh or strands from marine supply stores).
   3. Polyester or epoxy resin (available in cans from marine supply stores).
2. Emery paper
3. 600 grit aluminum oxide paper

2.03 EQUIPMENT

1. Wiping cloths
2. Eye and skin protection
3. Putty knife

PART 3–EXECUTION

3.01 PREPARATION

1. Surface Preparation:
   1. Surface preparation shall be done under the supervision of the RHPO.
   2. The RHPO will designate sample areas for testing of surface preparation on the various different components that require repair. No other surface preparation is to be done until sample areas have been approved. Approved areas shall become the standard of comparison for all surface preparation work. Protect from weathering, but do not alter or opaquely cover sample areas until all preparation work has been completed and approved.
   3. The time interval between final cleaning and application of primer shall not exceed two hours. Prime coat shall be applied prior to application of plastic metal materials. Allow 48 hours between application of prime coat and application of plastic metal material.
   4. See 05010-17-R for cleaning and rust removal of metal surfaces prior to making metal repairs.

3.02 ERECTION, INSTALLATION, APPLICATION

1. Abrasively clean with sandpaper the pit and surrounding materials until all evidence of paint and corrosion is gone and a “white metal” condition is achieved. If the RHPO judges that the area cannot be adequately cleaned it shall be ground out.
2. Prime paint the area immediately (see 05010-13-S and 09900-07-S for guidance).
3. Carefully and completely fill hole, nick or imperfection with epoxy no sooner than 48 hours after prime painting and allow to dry.
4. When dry, apply second primer coat of paint over the patch and finish with paint to match existing.