Article originally published in the FABRICATOR magazine Nov/Dec 1999 Edition and was written by Robert A. Baird who was the president of Cast Iron Restoration Management and one of the original founders of Historical Arts & Casting, a firm specializing in the design and manufacturing of architectural cast metal ornamentation.

The Rebirth Of A Cast Iron Gem (Part 2 of 3)

A community rallies to the cause of restoring a beloved courthouse.

By Robert A. Baird

Time to Restore

Prior to starting the actual restoration, 43,000 pounds of pigeon waste and other debris were removed from the attic.  Scaffolding was erected from the ground for the pavilions but was cantilevered off the masonry around the corner domes.  Scaffolding was also set around the central dome.  An elevator lift was set up from the ground to the rooftop allow for the movement of material to and from the building.

Dismantling

With the site ready to start work, the laborious task of removing every piece of cast iron from the top of the central dome was started.  Each piece of iron was documented, catalogued, and then later inspected and numbered during the removal process.  Severely corroded material was scrapped and all usable material was removed from the site to be sandblasted and repainted.  Over 15,000 cast iron parts ranging from a few pounds to several hundred pounds were removed.  The demolition and installation crews grew to as many as 25 men and the work went year round after the first winter.

Restoring the Structure & Iron

The beauty of cast iron structures from this period is their simplicity.  The Miami County Courthouse was no exception, with a simple riveted iron structure or framework laced together with tie rods supporting the cast iron skin.  The combination of the cast iron bolted to the riveted iron structure created a very sound roof support system.  For the most part, the structure was in good condition and needed only to be cleaned, painted, and some minor reinforcement.  All of this work was completed in the field.

The restoration program for the cast iron was quite a bit more involved than the structure.  Over 50 percent of the cast iron had to be replaced, which meant new patterns were needed and new components cast.  Over 700 patterns had to be manufactured to produce the thousands of cast iron parts required.  Because shrinkage was critical, old parts could not be used as patterns.  Historical Arts and Casting had the responsibility of not only restoring the old parts but also manufacturing the new iron and installation.

One of the key elements of the restoration was the cleaning and painting of the cast iron, which ultimately would provide long-term protection for the iron.  Tnemec Corp. was very helpful in assisting with technical support and providing testing throughout the course of the project.  Their four-part paint system included zinc rich primers, intermediate high build epoxy, and two finish coats of urethane.  Cast iron parts were sandblasted and pre-finished prior to delivery to the job site.  After the installation, additional coats of paint were applied in the field.

The second major consideration during the cast iron restoration was the waterproofing.  The reason for the cast iron failure in the first place was the lack of adequate waterproofing.  We were confident that if we focused on waterproofing issues and thoroughly resolved them we could dramatically increase the life of the cast iron.  When new parts were required, we tried to improve on how they were built, adding flanges and lap joints to improve their ability to shed water.  Thousands of linear feet of vertical and horizontal joints were caulked with Dow Corning’s silicone system.

The last installment will be posted on Monday, May 3rd, 2010. Stay tuned.

Part 1 of 3

Tags: Cast Iron, Historical Renovation, Historical Restoration, Miami County Couthouse, Robert A. Baird

Send an email to the author of this post at robert@historicalarts.com.