27 PRESERVATION 

BRIEFS 

The Maintenance and Repair of 

Architectural Cast Iron 

John G. Waite, AlA 

Historical Overview by Margot Gayle 

U.S. Department of the Interior 

National Park Service 

Cultural Resources 

Preservation Assistance 

The preservation of cast-iron architectural elements, 

including entire facades, has gained increasing attention in 

recent years as commercial districts are recognized for their 

historic significance and revitalized. This Brief provides 

general guidance on approaches to the preservation and 

restoration of historic cast iron. 

Cast iron played a preeminent role in the industrial 

development of our country during the 19th century. Castiron machinery filled America's factories and made possible 

the growth of railroad transportation. Cast iron was used 

extensively in our cities for water systems and street 

lighting. As an architectural metal, it made possible bold 

new advances in architectural designs and building 

technology, while providing a richness in ornamentation 

(Fig. 1). 

This age-old metal, an iron alloy with a high carbon content, 

had been too costly to make in large quantities until the 

mid-18th century, when new furnace technology in England 

made it more economical for use in construction. Known 

for its great strength in compression, cast iron in the form of 

slender, non-flammable pillars, was introduced in the 1790s 

in English cotton mills, where fires were endemic. In the 

United States, similar thin columns were first employed in 

the 1820s in theaters and churches to support balconies. 

By the mid-1820s, one-story iron storefronts were being 

advertised in New York City. Daniel Badger, the Boston 

foundryman who later moved to New York, asserted that in 

1842 he fabricated and installed the first rolling iron 

shutters for iron storefronts, which provided protection 

against theft and external fire. In the years ahead, and into 

the 1920s, the practical cast-iron storefront would become a 

favorite in towns and cities from coast to coast. Not only 

did it help support the load of the upper floors, but it 

provided large show windows for the display of wares and 

allowed natural light to flood the interiors of the shops. 

Most importantly, cast-iron storefronts were inexpensive to 

assemble, requiring little on-site labor. 

A tireless advocate for the use of cast iron in buildings was 

an inventive New Yorker, the self-taught architect/engineer 

In Cooperation with the 

New York Landmarks Conservancy 

James Bogardus. From 1840 on, Bogardus extolled its 

virtues of strength, structural stability, durability, relative 

lightness, ability to be cast in almost any shape and, above 

all, the fire-resistant qualities so sought after in an age of 

serious urban conflagrations. He also stressed that the 

foundry casting processes, by which cast iron was made 

into building elements, were thoroughly compatible with 

the new concepts of prefabrication, mass production, and 

use of identical interchangeable parts. 

Fig. 1. The Haughwout Building in New York City is all excellent 

example of the quality and character of mass-produced cast-iron 

architecture. On.ce wood patterns were made, any number of elements 

could be cast, as was done with each of these repetitive bays. Photo: 

New York City Landmarks Preservation Commission. 
2 

In 1849 Bogardus created something uniquely American 

when he erected the first structure with self-supporting, 

multi-storied exterior walls of iron. Known as the Edgar 

Laing Stores, this corner row of small four-story 

warehouses that looked like one building was constructed 

in lower Manhattan in only two months. Its rear, side, and 

interior bearing walls were of brick; the floor framing 

consisted of timber joists and girders. One of the cast-iron 

walls was load-bearing, supporting the wood floor joists. 

The innovation was its two street facades of self-supporting 

cast iron, consisting of multiples of only a few piecesDoric-style engaged columns, panels, sills, and plates, along 

with some applied ornaments (cover photo and Fig. 2). 

Each component of the facades had been cast individually 

in a sand mold in a foundry, machined smooth, tested for 

fit, and finally trundled on horse-drawn drays to the 

building site. There they were hoisted into position, then 

bolted together and fastened to the conventional structure 

of timber and brick with iron spikes and straps (Fig. 3). 

The second iron-front building erected was a quantum leap 

beyond the Laing Stores in size and complexity. Begun in 

April 1850 by Bogardus, with architect Robert Hatfield, the 

five-story Sun newspaper building in Baltimore was both 

cast-iron-fronted and cast-iron-framed. In Philadelphia, 

Fig. 2. The Edgar Lazng zn New was t1eS:lqm~t1 

by James Bogardus. It was the first building constructed with facades 

of self-supporting cast iron. This corner view shows the Doric-style 

engaged columns, panels, and spandrel beams; the loss of most of the 

original ornamental castings give it an austere look. As part of an 

urban renewal project, the facades were carefully disassembled in 1971 

for later re-erection in another location-only to have its iron parts 

stolen for scrap. Photo: Jack E. Boucher, HABS Collection. 

several ironfronts were begun in 1850: The Inquirer 

Building, the Brock Stores, and the Penn Mutual Building 

(all three have been demolished). The St. Charles Hotel of 

1851 at 60 N. Third Street is the oldest ironfront in America. 

Framing with cast-iron columns and wrought-iron beams 

and trusses was visible on a vast scale in the New York 

Crystal Palace of 1853. 

In the second half of the 19th century, the United States was 

in an era of tremendous economic and territorial growth. 

The use of iron in commercial and public buildings spread 

rapidly, and hundreds of iron-fronted buildings were 

erected in cities across the country from 1849 to beyond the 

turn of the century. Outstanding examples of ironfronts 

exist in Baltimore, Galveston, Louisville, Milwaukee, New 

Orleans, Philadelphia, Richmond, Rochester (N.Y.), and 

especially New York City where the SoHo Cast Iron 

Historic District alone has 139 iron-fronted buildings 

(Fig. 1). Regrettably, a large proportion of ironfronts 

nationwide have been demolished in downtown 

redevelopment projects, especially since World War II. 

ROOF (CONSTRUCTION NOT ACCESSIBLE) 

WINDOW 

CONSTRUCTION 

(NOT ORIGINAL) 

WOODEN~~===t~j 

SPACER 

BOLT 

WOODEN JOIST 

IRON COLUMN 

I 

~ I PLAN OF COLUMN IRON PANEL 

IRON PANEL 

FLOOR 

FLANGE 

BOLT 

<> 

WOODEN JOIST 

SECTION THROUGH WALL 

Fig. 3. Section drawing through the wall of Edgar Laing Stores showing 

how the cast-iron facade components were anchored to the wood floor and 

roof framing members. Drawing: John G. Waite, HABS Collection. 
Fig. 4. The 1904 grand stairway of the former Frear's department 

store in Troy, N.Y. was constructed of cast iron, as was the frame of 

the skylight above. Some ornamental wrought iron was also 

employed. This use of iron was typical in major commercial bllildings 

constructed throughout the United States. Courtesy: Rensselaer 

Cou nty Historical Society. 

In addition to these exterior uses, many public buildings 

display magnificent exposed interior ironwork, at once 

ornamental and structural (Fig. 4). Remarkable examples 

have survived across the country, including the Peabody 

Library in Baltimore; the Old Executive Office Building in 

Washington, D.C.; the Bradbury Building in Los Angeles; 

the former Louisiana State Capitol; the former City Hall in 

Richmond; Tweed Courthouse in New York; and the state 

capitols of California, Georgia, Michigan, Tennessee, and 

Texas. And it is iron, of course, that forms the great dome 

of the United States Capitol, completed during the Civil 

War. Ornamental cast iron was a popular material in the 

landscape as well, appearing as fences, fountains with 

statuary, lampposts, furniture, urns, gazebos, gates, and 

enclosures for cemetery plots (Fig. 5). With such 

widespread demand, many American foundries that had 

been casting machine parts, bank safes, iron pipe, or 

cookstoves added architectural iron departments (Fig. 6). 

These called for patternmakers with sophisticated design 

capabilities, as well as knowledge of metal shrinkage and 

other technical aspects of casting. Major companies 

included the Hayward Bartlett Co. in Baltimore; James L. 

Jackson, Cornell Brothers, J. L. Mott, and Daniel D. Badger's 

Architectural Iron Works in Manhattan; Hecla Ironworks in 

Brooklyn; Wood & Perot of Philadelphia; Leeds & Co., the 

Fig. 5. The Slatter Falllily Tomb ill Mobile, Alabama, consisting of a 

cast-irol/ mausoleum and fence, exhibits the wide rallge of uses of the 

material ill the 19th century. Photo: Jack E. Boucher, HABS 

Collectioll. 

Shakspeare (sic) Foundry, and Miltenberger in New 

Orleans; Winslow Brothers in Chicago; and James 

McKinney in Albany, N.Y. 

Cast iron was the metal of choice throughout the second 

half of the 19th century. Not only was it a fire-resistant 

material in a period of major urban fires, but also large 

facades could be produced with cast iron at less cost than 

comparable stone fronts, and iron buildings could be 

erected with speed and efficiency. The largest standing 

example of framing with cast-iron columns and wroughtiron beams is Chicago'S sixteen-story Manhattan Building, 

the world's tallest skyscraper when built in 1890 by William 

LeBaron Jenney. By this time, however, steel was becoming 

available nationally, and was structurally more versatile 

and cost-competitive. Its increased use is one reason why 

building with cast iron diminished around the turn of the 

century after having been so eagerly adopted only fifty 

years before. Nonetheless, cast iron continued to be used in 

substantial quantities for many other structural and 

ornamental purposes well into the 20th century: storefronts; 

marquees; bays and large window frames for steel-framed, 

masonry-clad buildings; and street and landscape 

furnishings, including subway kiosks. 

The 19th century left us with a rich heritage of new building 

methods, especially construction on an altogether new scale 

that was made possible by the use of metals. Of these, cast 

iron was the pioneer, although its period of intensive use 

lasted but a half century. Now the surviving legacy of castiron architecture, much of which continues to be threatened, 

merits renewed appreciation and appropriate preservation 

and restoration treatments. 

3 
4 

What is Cast Iron? 

Cast iron is an alloy with a high carbon content (at 

least 1.7% and usually 3.0 to 3.7%) that makes it more 

resistant to corrosion than either wrought iron or steel. 

In addition to carbon, cast iron contains varying 

amounts of silicon, sulfur, manganese, and 

phosphorus. 

While molten, cast iron is easily poured into molds, 

making it possible to create nearly unlimited 

decorative and structural forms. Unlike wrought iron 

and steel, cast iron is too hard and brittle to be shaped 

by hammering, rolling, or pressing. However, because 

it is more rigid and more resistant to buckling than 

other forms of iron, it can withstand great compression 

loads. Cast iron is relatively weak in tension, however, 

and fails under tensile loading with little prior 

warning. 

The characteristics of various types of cast iron are 

determined by their composition and the techniques 

used in melting, casting, and heat treatment. 

Metallurgical constituents of cast iron that affect its 

brittleness, toughness, and strength include ferrite, 

cementite, pearlite, and graphite carbon. Cast iron 

with flakes of carbon is called gray cast iron. The 

"gray fracture" associated with cast iron was probably 

named for the gray, grainy appearance of its broken 

edge caused by the presence of flakes of free graphite, 

which account for the brittleness of cast iron. This 

brittleness is the important distinguishing 

characteristic between cast iron and mild steel. 

Compared with cast iron, wrought iron is relatively 

soft, malleable, tough, fatigue-resistant, and readily 

worked by forging, bending, and drawing. It is almost 

pure iron, with less than 1 % (usually 0.02 to 0.03%) 

carbon. Slag varies between 1 % and 4% of its content 

and exists in a purely physical association, that is, it is 

not alloyed. This gives wrought iron its characteristic 

laminated (layered) or fibrous structure. 

Wrought iron can be distinguished from cast iron in 

several ways. Wrought-iron elements generally are 

simpler in form and less uniform in appearance than 

cast-iron elements, and contain evidence of rolling or 

hand working. Cast iron often contains mold lines, 

flashing, casting flaws, and air holes. Cast-iron 

elements are very uniform in appearance and are 

frequently used repetitively. Cast-iron elements are 

often bolted or screwed together, whereas wroughtiron pieces are either riveted or forge-molded (heat 

welded) together. 

Mild steel is now used to fabricate new hand-worked 

metal work and to repair old wrought-iron elements. 

Mild steel is an alloy of iron and is not more than 2% 

carbon, which is strong but easily worked in block or 

ingot form. Mild steel is not as resistant to corrosion as 

either wrought iron or cast iron. 

Maintenance and Repair 

Many of the maintenance and repair techniques described 

in the Brief, particularly those relating to cleaning and 

painting, are potentially dangerous and should be carried 

out only by experienced and qualified workmen using 

protective equipment suitable to the task. In all but the 

most simple repairs, it is best to involve a preservation 

architect or building conservator to assess the condition of 

the iron and prepare contract documents for its treatment. 

As with any preservation project, the work must be 

preceded by a review of local building codes and 

environmental protection regulations to determine whether 

any conflicts exist with the proposed treatments. If there are 

conflicts, particularly with cleaning techniques or painting 

materials, then waivers or variances need to be negotiated, 

or alternative treatments or materials adopted. 

Deterioration 

Common problems encountered today with cast-iron 

construction include badly rusted or missing elements, 

impact damage, structural failures, broken joints, damage to 

connections, and loss of anchorage in masonry (Figs. 7,8). 

Oxidation, or rusting, occurs rapidly when cast iron is 

exposed to moisture and air. The minimum relative 

humidity necessary to promote rusting is 65%, but this 

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Fig. 6. Sheet from a late 19th century manufacturer's trade catalog 

illustrates some of the products available from foundries, such as 

storefronts, girders and beams, columns, stairs, window lintels and sills, 

and roof crestings. Courtesy: Albany Institute of History and Art. 
Fig. 7. Despite Illl 

illlpilct thllt sllll ttered 

the IIlllill CIlstings, 

th is fe li ce post 

rell1aillS IIprigh t, 

dell10llstmtillg the 

grl'll t strellgth of CIlst 

iroll. Origilllllly, the 

post WIlS held 

together by Il 10llg 

bolt thllt extcllded 

fro lll the fill ill I to the 

bllsc. Photo: Johll G. 

Wilite. 

figure can be lower in the presence of corrosive agents, such 

as sea water, salt air, acids, acid precipitation, soils, and 

some sulfur compounds present in the atmosphere, which 

act as catalysts in the oxidation process. Rusting is 

accelerated in situations where architectural details provide 

pockets or crevices to trap and hold liquid corrosive agents. 

Furthermore, once a rust film forms, its porous surface acts 

as a reservoir for liquids, which in turn causes further 

corrosion. If this process is not arrested, it will continue 

until the iron is entirely consumed by corrosion, leaving 

nothing but rust. 

Galvanic corrosion is an electrochemical action that results 

when two dissimilar metals react together in the presence of 

an electrolyte, such as water containing salts or hydrogen 

ions (Fig. 9). The severity of the galvanic corrosion is based 

Fig. 8. Structural cracks, gaps at joints between components, and a 

la rge opening where part of the console bracket is missing are the 

problems evident in this cast-iron assembly. Photo: Ford, Powell & 

Carson. 

on the difference in potential between the two metals, their 

relative surface areas, and time. If the more noble metal 

(higher position in electrochemical series) is much larger in 

area than the baser, or less noble, metal, the deterioration of 

the baser metal will be more rapid and severe. If the more 

noble metal is much smaller in area than the baser metal, 

the deterioration of the baser metal will be much less 

significant. Cast iron will be attacked and corroded when it 

is adjacent to more noble metals such as lead or copper. 

Fig. 9. Galvanic 

corrosion occurred 

where Il patch of 

copper was installed 

Illongside the castiron CIlp Ilt the base 

ofilfolllltaill. The 

lise of teme-coated 

stainless flashings 

with Ilppropriate 

CIllllkillg would hllve 

beell a more sllitable 

repllir. Photo: John 

G. Wilite. 

Graphitization of cast iron, a less common problem, occurs 

in the presence of acid precipitation or seawater. As the 

iron corrodes, the porous graphite (soft carbon) corrosion 

residue is impregnated with insoluble corrosion products. 

As a result, the cast-iron element retains its appearance and 

shape but is weaker structurally. Graphitization occurs 

where cast iron is left unpainted for long periods or where 

caulked joints have failed and acidic rainwater has corroded 

pieces from the backside. Testing and identification of 

graphitization is accomplished by scraping through the 

surface with a knife to reveal the crumbling of the iron 

beneath. Where extensive graphitization occurs, usually the 

only solution is replacement of the damaged element. 

Castings may also be fractured or flawed as a result of 

imperfections in the original manufacturing process, such as 

air holes, cracks, and cinders, or cold shuts (caused by the 

"freezing" of the surface of the molten iron during casting 

because of improper or interrupted pouring). Brittleness is 

another problem occasionally found in old cast-iron 

elements. It may be a result of excessive phosphorus in the 

iron, or of chilling during the casting process. 

Condition Assessment 

Before establishing the appropriate treatment for cast-iron 

elements in a building or structure, an evaluation should be 

made of the property's historical and architectural 

significance and alterations, along with its present 

condition. If the work involves more than routine 

maintenance, a qualified professional should be engaged to 

develop a historic structure report which sets forth the 

historical development of the property, documents its 

existing condition, identifies problems of repair, and 

provides a detailed listing of recommended work items 

5 
6 

witn priorities. Through this process the significance and 

condition of the cast iron can be evaluated and appropriate 

treatments proposed. For fences, or for single components 

of a building such as a facade, a similar but less extensive 

analytical procedure should be followed. 

The nature and extent of the problems with the cast-iron 

elements must be well understood before proceeding with 

work. If the problems are minor, such as surface corrosion, 

flaking paint, and failed caulking, the property owner may 

be able to undertake the repairs by working directly with a 

knowledgeable contractor. If there are major problems or 

extensive damage to the cast iron, it is best to secure the 

services of an architect or conservator who specializes in the 

conservation of historic buildings. Depending on the scope 

of work, contract documents can range from outline 

specifications to complete working drawings with 

annotated photographs and specifications 

To thoroughly assess the condition of the ironwork, a close 

physical inspection must be undertaken of every section of 

the iron construction including bolts, fasteners, and brackets 

(Fig. 10). Typically, scaffolding or a mechanical lift is 

employed for close inspection of a cast-iron facade or other 

large structures. Removal of select areas of paint may be 

the only means to determine the exact condition of 

connections, metal fasteners, and intersections or crevices 

that might trap water. 

DETERIORATED 

FLASHING, RAISED --------~-"""'= 

EDGES 

HOLE:----------

OPEN JOINTS 

MISSING LEAVES 

AND SCROLL FROM 

CAPITAL 

DETERIORATED 

FLASHING, GAP 

AT EDGE 

HOLE AND OPEN 

JOINT ---

STRIP FLASHING 

LACKS CAULK ------

Fig. 11. Major cracks in the piers of this cast-iron storefront in 

Galveston, Texas resulted from the transfer of load onto the iron from 

internal brick piers eroded by rising damp. This crack was 

inappropriately filled with concrete, which trapped moisture and 

accelerated internlll corrosion, pushing the iron further apart. Photo: 

Ford, Powell & Carson. 

:::::i::;::::::::::::=:==----- FAILED PATCH 

____ MISSING PIECE OF 

SOFFIT MOLDING 

---- FRACTURE IN CASTING 

___ FRACTURE IN CASTING 

OPEN JOINT AT 

------- SCROLL 

------- MISSING LEAVES 

':----"'---'7Iiililiiii~r_----- CORROSION 

Fig. 10. During close-up inspection of the Gunther Building in New York City, photographs of each bay were taken to use in a survey of existing 

conditions. Photo: Willcox Dunn. 
An investigation of load-bearing elements, such as columns 

and beams, will establish whether these components are 

performing as they were originally designed, or the stress 

patterns have been redistributed. Areas that are abnormally 

stressed must be examined to ascertain whether they have 

suffered damage or have been displaced (Fig. 11). Damage 

to a primary structural member is obviously critical to 

identify and evaluate; attention should not be given only to 

decorative features. 

The condition of the building, structure, or object; diagnosis 

of its problems; and recommendations for its repair should 

be recorded by drawings, photographs, and written 

descriptions, to aid those who will be responsible for its 

conservation in the future. 

Whether minor or major work is required, the retention and 

repair of historic ironwork is the recommended 

preservation approach over replacement. All repairs and 

restoration work should be reversible, when possible, so 

that modifications or treatments that may turn out to be 

harmful to the long-term preservation of the iron can be 

corrected with the least amount of damage to the historic 

ironwork. 

Cleaning and Paint Removal 

When there is extensive failure of the protective coating 

and/ or when heavy corrosion exists, the rust and most or 

all of the paint must be removed to prepare the surfaces for 

new protective coatings. The techniques available range 

from physical processes, such as wire brushing and grit 

blasting, to flame cleaning and chemical methods. The 

selection of an appropriate technique depends upon how 

much paint failure and corrosion has occurred, the fineness 

of the surface detailing, and the type of new protective 

coating to be applied. Local environmental regulations may 

restrict the options for cleaning and paint removal methods, 

as well as the disposal of materials. 

Many of these techniques are potentially dangerous and 

should be carried out only by experienced and qualified 

workers using proper eye protection, protective clothing, 

and other workplace safety conditions. Before selecting a 

process, test panels should be prepared on the iron to be 

cleaned to determine the relative effectiveness of various 

techniques. The cleaning process will most likely expose 

additional coating defects, cracks, and corrosion that have 

not been obvious before (Fig. 12 ). 

There are a number of techniques that can be used to 

remove paint and corrosion from cast iron: 

Hand scraping, chipping, and wire brushing are the most 

common and least expensive methods of removing paint 

and light rust from cast iron (Fig. 13a, b). However, they do 

not remove all corrosion or paint as effectively as other 

methods. Experienced craftsmen should carry out the work 

to reduce the likelihood that surfaces may be scored or 

fragile detail damaged. 

Low-pressure grit blasting <Commonly called abrasive 

cleaning or sandblasting) is often the most effective 

approach to removing excessive paint build-up or 

substantial corrosion. Grit blasting is fast, thorough, and 

economical, and it allows the iron to be cleaned in place. 

The aggregate can be iron slag or sand; copper slag should 

not be used on iron because of the potential for electrolytic 

Fig. 12. Paint stripping exposed a large defect ullder a faulty patch at a 

joint of this wide cast-iron watertable. The damage can be repaired 

mechanically by splicing in a cast-iron replacemellt piece. Photo: Peter 

Jensen, Kapell and Kostow Architects. 

reactions. Some sharpness in the aggregate is beneficial in 

that it gives the metal surface a "tooth" that will result in 

better paint adhesion. The use of a very sharp or hard 

aggregate and/ or excessively high pressure (over 100 

pounds per square inch) is unnecessary and should be 

avoided. Adjacent materials, such as brick, stone, wood, 

and glass, must be protected to prevent damage. Some 

local building codes and environmental authorities prohibit 

or limit dry sandblasting because of the problem of airborne 

dust. 

Wet sandblasting is more problematic than dry 

sandblasting for cleaning cast iron because the water will 

cause instantaneous surface rusting and will penetrate deep 

into open joints. Therefore, it is generally not considered an 

effective technique. Wet sandblasting reduces the amount 

of airborne dust when removing a heavy paint build-up, 

but disposal of effluent containing lead or other toxic 

substances is restricted by environmental regulations in 

most areas. 

Flame cleaning of rust from metal with a special multiflame head oxyacetylene torch requires specially skilled 

operators, and is expensive and potentially dangerous. 

However, it can be very effective on lightly to moderately 

corroded iron. Wire brushing is usually neccessary to finish 

the surface after flame cleaning. 

Chemical rust removal, by acid pickling, is an effective 

method of removing rust from iron elements that can be 

easily removed and taken to a shop for submerging in vats 

of dilute phosphoric or sulfuric acid. This method does not 

damage the surface of iron, providing that the iron is 

neutralized to pH level 7 after cleaning. Other chemical 

rust removal agents include ammonium citrate, oxalic acid, 

or hydrochloric acid-based products. 

7 
8 

Fig. 13. S~rface preparation may involve several different techniques. Where chemical paint stripping is involved, careful planning of the sequence of 

work and inspectIOn by an architect or con~ervator to ensure stnct compliance ~Ith the cont~act documents is important to minimize the risk of 

probLems. After the chemical paste and pall1twas scraped off, the remamlng paint and chemicaL residue were removed with a wire brush (a) and 

scraper~ selected or cut to fit the shape of the Iron surfaces (b). The surface was then wiped with solvent to create a compLetely clean surface prior to 

repainting (c). Photos: Raymond M. Pepl, BUlLdlllg ConservatIOn Associates. 

Chemical paint removal using alkaline compounds, such as 

methylene chloride or potassium hydroxide, can be an 

effective alternative to abrasive blasting for removal of 

heavy paint build-up (Fig. 13). These agents are often 

available as slow-acting gels or pastes. Because they can 

cause burns, protective clothing and eye protection must be 

worn. Chemicals applied to a non-watertight facade can 

seep through crevices and holes, resulting in damage to the 

building's interior finishes and corrosion to the backside of 

the iron components. If not thoroughly neutralized, 

residual traces of cleaning compounds on the surface of the 

iron can cause paint failures in the future (Fig. 14). For 

these reasons, field application of alkaline paint removers 

and acidic cleaners is not generally recommended. 

Following any of these methods of cleaning and paint 

removal, the newly cleaned iron should be painted 

immediately with a corrosion-inhibiting primer before new 

rust begins to form. This time period may vary from 

minutes to hours depending on environmental conditions. 

If priming is delayed, any surface rust that has developed 

should be removed with a clean wire brush just before 

priming, because the rust prevents good bonding between 

the primer and the cast iron surface and prevents the primer 

from completely filling the pores of the metal. 

Painting and Coating Systems 

The most common and effective way to preserve 

architectural cast iron is to maintain a protective coating of 

paint on the metal. Paint can also be decorative, where 

historically appropriate. 

Before removing paint from historic architectural cast 

iron, a microscopic analysis of samples of the historic 

paint sequencing is recommended. Called paint 

seriation analysis, this process must be carried out by an 

experienced architectural conservator. The analysis will 

identify the historic paint colors, and other conditions, 

such as whether the paint was matte or gloss, whether 

sand was added to the paint for texture, and whether 

the building was polychromed or marbleized. 

Traditionally many cast-iron elements were painted to 

resemble other materials, such as limestone or 

sandstone. Occasionally, features were faux-painted so 

that the iron appeared to be veined marble. 

Thorough surface preparation is necessary for the adhesion 

of new protective coatings. All loose, flaking, and 

deteriorated paint must be removed from the iron, as well 

as dirt and mud, water-soluble salts, oil, and grease. Old 

paint that is tightly adhered may be left on the surface of 

the iron if it is compatible with the proposed coatings. The 

retention of old paint also preserves the historic paint 

sequence of the building and avoids the hazards of removal 

and disposal of old lead paint. 

It is advisable to consult manufacturer's specifications or 

technical representatives to ensure compatibility between 

the surface conditions, primer and finish coats, and 

application methods. 

For the paint to adhere properly, the metal surfaces must be 

absolutely dry before painting. Unless the paint selected is 
specifically designed for exceptional conditions, painting 

should not take place when the temperature is expected to 

fall below 50 degrees Fahrenheit within 24 hours or when 

the relative humidity is above 80 per cent; paint should not 

be applied when there is fog, mist, or rain in the air. Poorly 

prepared surfaces will cause the failure of even the best 

paints, while even moderately priced paints can be effective 

if applied over well-prepared surfaces. 

Selection of Paints and Coatings 

The types of paints available for protecting iron have 

changed dramatically in recent years due to federal, state, 

and local regulations that prohibit or restrict the 

manufacture and use of products containing toxic 

substances such as lead and zinc chromate, as well as 

volatile organic compounds and substances (VOC or VOS). 

Availability of paint types varies from state to state, and 

manufacturers continue to change product formulations to 

comply with new regulations. 

Fig. 14. Major problems can result if work is undertaken without 

proper sequencing and precautions. On this building, a strong alkaline 

paint remover was used, and apparently was not adequately rinsed or 

neutralized. Over a period of months, the newly applied paint began to 

peel and streaks of rust appeared on the iron. Photo: Kim Lovejoy. 

Traditionally, red lead has been used as an anti-corrosive 

pigment for priming iron. Red lead has a strong affinity for 

linseed oil and forms lead soaps, which become a tough and 

elastic film impervious to water that is highly effective as a 

protective coating for iron. At least two slow-drying 

linseed oil-based finish coats have traditionally been used 

over a red lead primer, and this combination is effective on 

old or partially-deteriorated surfaces. Today, in most areas, 

the use of paints containing lead is prohibited, except for 

some commercial and industrial purposes. 

Today, alkyd paints are very widely used and have largely 

replaced lead-containing linseed-oil paints. They dry faster 

than oil paint, with a thinner film, but they do not protect 

the metal as long. Alkyd rust-inhibitive primers contain 

pigments such as iron oxide, zinc oxide, and zinc 

phosphate. These primers are suitable for previously 

painted surfaces cleaned by hand tools. At least two coats 

of primer should be applied, followed by alkyd enamel 

finish coats. 

Latex and other water-based paints are not recommended for 

use as primers on cast iron because they cause immediate 

oxidation if applied on bare metal. Vinyl acrylic latex or 

acrylic latex paints may be used as finish coats over alkyd 

rust-inhibitive primers, but if the primer coats are 

imperfectly applied or are damaged, the latex paint will 

cause oxidation of the iron. Therefore, alkyd finish coats are 

recommended. 

High-performance coatings, such as zinc-rich primers 

containing zinc dust, and modern epoxy coatings, can be 

used on cast iron to provide longer-lasting protection. 

These coatings typically require highly clean surfaces and 

special application conditions which can be difficult to 

achieve in the field on large buildings (Fig. 13c). These 

coatings are used most effectively on elements which have 

been removed to a shop, or newly cast iron. 

One particularly effective system has been first to coat 

commercially blast-cleaned iron with a zinc-rich primer, 

followed by an epoxy base coat, and two urethane finish 

coats. Some epoxy coatings can be used as primers on clean 

metal or applied to previously-painted surfaces in sound 

condition. Epoxies are particularly susceptible to 

degradation under ultraviolet radiation and must be 

protected by finish coats which are more resistant. There 

have been problems with epoxy paints which have been 

shop-applied to iron where the coatings have been nicked 

prior to installation. Field touching-up of epoxy paints is 

very difficult, if not impossible. This is a concern since iron 

exposed by imperfections in the base coat will be more 

likely to rust and more frequent maintenance will be 

required. 

A key factor to take into account in selection of coatings is 

the variety of conditions on existing and new materials on a 

particular building or structure. One primer may be needed 

for surfaces with existing paint; another for newly cast, 

chemically stripped, or blast-cleaned cast iron; and a third 

for flashings or substitute materials; all three followed by 

compatible finish coats. 

Application Methods 

Brushing is the traditional and most effective technique for 

applying paint to cast iron. It provides good contact 

between the paint and the iron, as well as the effective 

filling of pits, cracks, and other blemishes in the metal. 

The use of spray guns to apply paint is economical, but 

does not always produce adequate and uniform coverage. 

For best results, air less sprayers should be used by skilled 

operators. To fully cover fine detailing and reach recesses, 

spraying of the primer coat, used in conjunction with 

brushing, may be effective. 

Rollers should never be used for primer coat applications 

on metal, and are effective for subsequent coats only on 

large, flat areas. The appearance of spray-applied and 

roller-applied finish coats is not historically appropriate and 

should be avoided on areas such as storefronts which are 

viewed close at hand. 

9 
10 

Caulking, Patching, and Mechanical Repairs 

Most architectural cast iron is made of many small castings 

assembled by bolts or screws (Fig. 16a). Joints between 

pieces were caulked to prevent water from seeping in and 

causing rusting from the inside out. Historically, the seams 

were often caulked with white lead paste and sometimes 

backed with cotton or hemp rope; even the bolt and screw 

heads were caulked to protect them from the elements and 

to hide them from view. Although old caulking is 

sometimes found in good condition, it is typically crumbled 

from weathering, cracked from the structural settlement, or 

destroyed by mechanical cleaning. It is essential to replace 

deteriorated caulking to prevent water penetration. For 

good adhesion and performance, an architectural-grade 

polyurethane sealant or traditional white lead paste is 

preferred. 

Water that penetrates the hollow parts of a cast-iron 

architectural element causes rust that may streak down over 

other architectural elements. The water may freeze, causing 

the ice to crack the cast iron. Cracks reduce the strength of 

the total cast-iron assembly and provide another point of 

entry for water. Thus, it is important that cracks be made 

weathertight by using caulks or fillers, depending on the 

width of the crack. 

Filler compounds containing iron particles in an epoxy resin 

binder can be used to patch superficial, non-structural 

cracks and small defects in cast iron. The thermal 

expansion rate of epoxy resin alone is different from that of 

iron, requiring the addition of iron particles to ensure 

compatibility and to control shrinkage. Although the 

repaired piece of metal does not have the same strength as a 

homogeneous piece of iron, epoxy-repaired members do 

have some strength. Polyester-based putties, such as those 

used on auto bodies, are also acceptable fillers for small holes. 

In rare instances, major cracks can be repaired by brazing or 

welding with special nickel-alloy welding rods. Brazing or 

welding of cast iron is very difficult to carry out in the field 

and should be undertaken only by very experienced welders. 

In some cases, mechanical repairs can be made to cast iron 

using iron bars and screws or bolts. In extreme cases, 

Fig. 15. In an effort to repair this stair railing, concrete was poured 

around the wood spacer inside the railing casting. Water penetrated 

the railing and reacted with the concrete to accelerate the corrosion of 

the iron. Photo: John C. Waite. 

deteriorated cast iron can be cut out and new cast iron 

spliced in place by welding or brazing. However, it is 

frequently less expensive to replace a deteriorated cast-iron 

section with a new casting rather than to splice or reinforce 

it. Cast-iron structural elements that have failed must either 

be reinforced with iron and steel or replaced entirely. 

A wok!; cast-iron balustrade or railing can often be fixed 

by tightening all bolts and screws. Screws with stripped 

threads and seriously rusted bolts must be replaced. To 

compensate for corroded metal around the bolt or screw 

holes, new stainless steel bolts or screws with a larger 

diameter need to be used. In extreme cases, new holes may 

need to be tapped. 

The internal voids of balusters, newel posts, statuary, and 

other elements should not be filled with concrete; it is an 

inappropriate treatment that causes further problems (Fig. 

15). As the concrete cures, it shrinks, leaving a space 

between the concrete and cast iron. Water penetrating this 

space does not evaporate quickly, thus promoting further 

rusting. The corrosion of the iron is further accelerated by 

the alkaline nature of concrete. Where cast-iron elements 

have been previously filled with concrete, they need to be 

taken apart, the concrete and rust removed, and the interior 

surfaces primed and painted before the elements are 

reassembled. 

~ 

NEW STAINLESS '? > 

STEEL BOLTS / 

COLUMN 

Fig. 16. Architectural cast iron is made of many small components bolted 

and screwed together. (a) This exploded view of a storefront illustrates 

the variety of elements, including brackets, fasteners, and holes for bolts. 

(b) The storefront was replicated in cast iron because of the extensive 

damage and structural failure, a detail of which is shown in Fig. 11 . 

Drawing and photo: Historical Arts & Casting, Inc. 
Duplication and Replacement 

The replacement of cast-iron components is often the only 

practical solution when such features are missing, severely 

corroded, or damaged beyond repair, or where repairs 

would be only marginally useful in extending the functional 

life of an iron element (Fig. 16). 

Sometimes it is possible to replace small, decorative, nonstructural elements using intact sections of the original as a 

casting pattern. For large sections, new patterns of wood or 

plastic made slightly larger in size than the original will 

The Casting Process 

Architectural elements were traditionally cast in sand 

molds. The quality of the special sands used by 

foundries is extremely important; unlike most sands 

they must be moist. Foundries have their own 

formulas for sand and its admixtures, such as clay, 

which makes the sand cohesive even when the mold is 

turned upside down. 

A two-part mold (with a top and a bottom, or cope and 

drag) is used for making a casting with relief on both 

sides, whereas an open-top mold produces a flat 

surface on one side (Fig. 17a). For hollow elements, a 

third pattern and mold are required for the void. 

Many hollow castings are made of two or more parts 

that are later bolted, screwed, or welded together, 

because of the difficulty of supporting an interior core 

between the top and bottom sand molds during the 

casting process. 

need to be made in order to compensate for the shrinkage of 

the iron during casting (cast iron shrinks approximately 1/8 

inch per foot as it cools from a liquid into a solid). 

Occasionally, a matching replacement can be obtained from 

the existing catalogs of iron foundries. Small elements can 

be custom cast in iron at small local foundries, often at a 

cost comparable to substitute materials. Large elements 

and complex patterns will usually require the skills and 

facilities of a larger firm that specializes in replication. 

The molding sand is compacted into flasks, or forms, 

around the pattern. The cope is then lifted off and the 

pattern is removed, leaving the imprint of the pattern 

in the small mold. Molten iron, heated to a 

temperature of approximately 2700 degrees 

Fahrenheit, is poured into the mold and then allowed 

to cool (Fig. 17b). The molds are then stripped from 

the casting; the tunnels to the mold (sprues) and risers 

that allowed release of air are cut off; and ragged 

edges (called "burrs") on the casting are ground 

smooth. 

The castings are shop-primed to prevent rust, and laid 

out and preas sembled at the foundry to ensure proper 

alignment and fit. When parts do not fit, the pieces are 

machined to remove irregularities caused by burrs, or 

are rejected and recast until all of the cast elements fit 

together properly. Most larger pieces then are taken 

apart before shipping to the job site, while some small 

ornamental parts may be left assembled. 

Fig. 17. (a) A two-part mold, consisting of a cope (top) and drag (bottom) for a newel post. Photo: Architectural Iron Company, Inc. 

(b) Molten iron being poured into a mold containing sand at a foundry. The iron casting process has changed little in the past two centuries. 

Photo: Karen Huebner. 

11 
Fig. 18. This cast-iron storefront cornice was corroded beyond the 

point of repair, and could not be removed easily for replacement. 

Terne-coated stainless steel, the most durable metal for flashing cast 

iron, was applied to the cornice and fitted as closely as possible to the 

historic profile. Although painting is not necessary to protect ternecoated stainless steel, the cornice should be painted to be consistent 

with the historic character of the building. A primer which is 

compatible with the terne coating should be used. Photo: Dean Koga, 

Robert E. Meadows, P.C, Architects. 

Dismantling and Assembly of Architectural 

Components 

It is sometimes necessary to dismantle all or part of a castiron structure during restoration, if repairs cannot be 

successfully carried out in place. Dismantling should be 

done only under the direction of a preservation architect or 

architectural conservator who is experienced with historic 

cast iron. Extreme care must be taken since cast iron is very 

brittle, especially in cold weather. 

Dismantling should follow the reverse order of construction 

and re-erection should occur, as much as possible, in the 

exact order of original assembly. Each piece should be 

numbered and keyed to record drawings. When work must 

be carried out in cold weather, care needs to be taken to 

avoid fracturing the iron elements by uneven heating of the 

members. 

Both new castings and reused pieces should be painted with 

a shop-applied prime coat on all surfaces. All of the 

components should be laid out and preas sembled to make 

sure that the alignment and fit are proper. Many of the 

original bolts, nuts, and screws may have to be replaced 

with similar fasteners of stainless steel. 

After assembly at the site, joints that were historically 

caulked should be filled with an architectural-grade 

polyurethane sealant or the traditional white lead paste 

White lead has the advantage of longevity, although its use 

is restricted in many areas. 

12 

Flashings 

In some instances, it may be necessary to design and 

install flashings to protect areas vulnerable to water 

penetration. Flashings need to be designed and 

fabricated carefully so that they are effective, as well 

as unobtrusive in appearance. The most durable 

material for flashing iron is terne-coated stainless steel 

(Fig. 18). Other compatible materials are terne-coated 

steel and galvanized steel; however, these require 

more frequent maintenance and are less durable. 

Copper and lead-coated copper are not recommended 

for use as flashings in contact with cast iron because of 

galvanic corrosion problems. Galvanic problems can 

also occur with the use of aluminum if certain types of 

electrolytes are present. 

Substitute Materials 

In recent years, a number of metallic and non-metallic 

materials have been used as substitutes for cast iron, 

although they were not used historically with cast iron. The 

most common have been cast aluminum, epoxies, 

reinforced polyester (fiberglass), and glass fiber-reinforced 

concrete (GFRC). Factors to consider in using substitute 

materials are addressed in Preservation Briefs 16, which 

emphasizes that "every means of repairing deteriorating 

historic materials or replacing them with identical materials 

should be examined before turning to substitute materials." 

Cast aluminum has been used recently as a substitute for 

cast iron, particularly for ornately-detailed decorative 

elements. Aluminum is lighter in weight, more resistant to 

corrosion, and less brittle than cast iron. However, because 

it is dissimilar from iron, its placement in contact with or 

near cast iron may result in galvanic corrosion, and thus 

should be avoided. Special care must be taken in the 

application of paint coatings, particularly in the field. It is 

often difficult to achieve a durable coating after the original 

finish has failed. Because aluminum is weaker than iron, 

careful analysis is required whenever aluminum is being 

considered as a replacement material for structural cast-iron 

elements. 

Epoxies are two-part, thermo-setting, resinous materials 

which can be molded into virtually any form. When 

molded, the epoxy is usually mixed with fillers such as 

sand, glass balloons, or stone chips. Since it is not a metal, 

galvanic corrosion does not occur. When mixed with sand 

or stone, it is often termed epoxy concrete or polymer 

concrete, a misnomer because no cementitious materials are 

included. Epoxies are particularly effective for replicating 

small, ornamental sections of cast iron. Since it is not a 

metal, galvanic corrosion does not occur. Epoxy elements 

must have a protective coating to shield them from 

ultraviolet degradation. They are also flammable and 

cannot be used as substitutes for structural cast-iron 

elements. 

Reinforced polyester, commonly known as fiberglass, is 

often used as a lightweight substitute for historic materials, 

including cast iron, wood, and stone. In its most common 

form, fiberglass is a thin, rigid, laminate shell formed by 

pouring a polyester resin into a mold and then adding 

fiberglass for reinforcement. Like epoxies, fiberglass is non-
Fig. 19. (a) Fiberglass columns and aluminum capitals were installed 

to replicate the ornamental features on the east facade of the New 

Market Theater ill Portland, Oregon, that had been destroyed by 

previous occupants. Like cast iron, crisp ornamental details can be 

achieved with cast aluminum. Although aluminum may be in contact 

with fiberglass, galvanic corrosion may resuIt when aluminum is in 

direct contact with cast iron. Photo: William J. Hawkins, III. (b) The 

west facade of the theatre retains its original cast iron features. 

Photo: George McMath. 

corrosive, but is susceptible to ultraviolet degradation. 

Because of its rather flimsy nature, it cannot be used as a 

substitute for structural elements, cannot be assembled like 

cast iron and usually requires a separate anchorage system. 

It is unsuitable for locations where it is susceptible to 

damage by impact (Fig. 20), and is also flammable. 

Glass fiber-reinforced concrete, known as GFRC, is similar 

to fiberglass except that a lightweight concrete is 

substituted for the resin. GFRC elements are generally 

fabricated as thin shell panels by spraying concrete into 

forms. Usually a separate framing and anchorage system is 

required. GFRC elements are lightweight, inexpensive, and 

weather resistant. Because GFRC has a low shrinkage coefficient, molds can be made directly from historic elements. 

Fig. 20. The location of the feature must be taken into account if a 

substitute replacement material is being considered. This lightweight 

fiberglass column at street level sustained damage from impact within a 

few years of installation. The great strength of cast iron makes it ideal 

for storefronts and elements that must withstand heavy use. Photo: 

Building Conservation Associates. 

However, GFRC is very different physically and chemically 

from iron. If used adjacent to iron, it causes corrosion of the 

iron and will have a different moisture absorption rate. 

Also, it is not possible to achieve the crisp detail that is 

characteristic of cast iron. 

Maintenance 

A successful maintenance program is the key to the longterm preservation of architectural cast iron. Regular 

inspections and accurate record-keeping are essential. 

Biannual inspections, occurring ideally in the spring and 

fall, include the identification of major problems, such as 

missing elements and fractures, as well as minor items such 

as failed caulking, damaged paint, and surface dirt. 

Records should be kept in the form of a permanent 

maintenance log which describes routine maintenance tasks 

and records the date a problem is first noted, when it was 

corrected, and the treatment method. Painting records are 

important for selecting compatible paints for touch-up and 

subsequent repainting. The location of the work and the 

type, manufacturer, and color of the paint should be noted 

in the log. The same information also should be assembled 

and recorded for caulking. 

Superficial dirt can be washed off well-painted and caulked 

cast iron with low-pressure water. Non-ionic detergents 

may be used for the remo\',li of heavy or tenacious dirt or 

stains, after testing to determine that they have no adverse 

effects on the painted surfaces. Thick grease deposits and 

residue can be removed by hand scraping. Water and 

detergents or non-caustic degreasing agents can be used to 

clean off the residue. Before repainting, oil and grease must 

be removed so that new coatings will adhere properly. 

13 
14 

The primary purpose of the maintenance program is to 

control corrosion. As soon as rusting is noted, it should be 

carefully removed and the protective coating of the iron 

renewed in the affected area. Replacement of deteriorated 

caulking, and repair or replacement of failed flashings are 

also important preventive maintenance measures. 

Summary 

The successful conservation of cast-iron architectural 

elements and objects is dependent upon an accurate 

diagnosis of their condition and the problems affecting 

them, as well as the selection of appropriate repair, 

cleaning, and painting procedures. Frequently, it is 

necessary to undertake major repairs to individual elements 

and assemblies; in some cases badly damaged or missing 

components must be replicated. The long-term 

preservation of architectural cast iron is dependent upon 

both the undertaking of timely, appropriate repairs and the 

commitment to a regular schedule of maintenance. 

Detail of polychromed cast-iron facade at 23 Petaluma Boulevard, 

Petaluma, Calif. (1886; O'Connell and Lewis, Architectural Iron 

Work, San Francisco). Photo: Don Meacham. 

Acknowledgements 

This Preservation Brief was developed by the New York Landmarks Conservancy's 

Technical Preservation Services Center under a cooperative agreement with the 

National Park Service's Preservation Assistance Division, and with partial funding 

from the New York State Council on the Arts. The following individuals are to be 

thanked for their technical assistance: Robert Baird, Historical Arts & Casting; 

Willcox Dunn, Architect and Cast Iron Consultant; William Foulks, Mesick Cohen 

Waite Architects; Elizabeth Frosch, New York City Landmarks Preservation 

Commission; William Hawkins, III, FAIA, McMath Hawkins Dortignacq; J. Scott 

I lowell, Robinson Iron Company; David Look, AlA, National Park Service; Donald 

Quick, Architectural Iron Company; Maurice Schickler, Facade Consultants 

International; Joel Schwartz, Schwartz and Schwartz Metalworks; and Diana Waite, 

Mount Ida Press. Kim Lovejoy was project coordinator and editor for the 

Conservancy; Charles Fisher was project coordinator and editor for the National 

Park Service. 

Reading List 

Ashurst, John, and Nicola Ashurst with Geoff Wallis and Dennis Toner. 

Practical Building Conservation: English Heritage Technical Handbook: 

Volume 4 Metals. Aldershot, Hants: Gower Technical Press, 1988. 

Badger, Daniel D., with a new introduction by Margot Gayle. Badger's 

Illustrated Catalogue of Cast-Iron Architecture. New York: Dover 

Publications, Inc., 1981; reprint of 1865 edition published by Baker & 

Godwin, Printers, New York. 

Gayle, Margot, and Edmund V. Gillon, Jr. Cast-Iron Architecture in New 

York: A Photographic Survey. New York: Dover Publications Inc., 1974. 

Gayle, Margot, David W. Look, AlA, and John G. Waite. Metals in 

America's Historic Buildings: Part I. A Historical Survey of Metals; Part II. 

Deterioration and Methods of Preservillg Metals. Washington, D.C; 

Preservation Assistance Division, National Park Service, 

U.s. Department of the Interior, 1980. 

Hawkins, William John III. The Grand Era of Cast Iron Architecture in 

Portland. Portland, Oregon: Binford & Mort, 1976. 

Howell, J. Scott. "Architectural Cast Iron: Design and Restoration," The 

Journal of the Association for Preservation Technology. Vol XIX, Number 3 

(1987), pp. 51-55. 

Park, Sharon C, AlA. Preservation Briefs 16: The Use of Substitute 

Materials on Historic Building Exteriors. Washington D. c.: Preservation 

Assistance Division, National Park Service, U. S. Department of the 

Interior, 1988. 

Robertson, E. Graeme, and Joan Robertson. Cast Iron Decoration: A World 

Survey. New York: Watson-Guptill Publications, 1977. 

Southworth, Susan and Michael. Ornamental Ironwork: An Illustrated 

Guide to Its Design, History, and Use in American Architecture. Boston: 

David R. Godine, 1978. 

Waite, Diana S. Ornamental Ironwork: Two Centuries of Craftsmanship in 

Albany and Troy, New York. Albany, NY: Mount Ida Press, 1990. 

This publication has been prepared pursuant to the Nationa l Historic Preservation 

Act amendments of 1980, which direct the Secretary of the Interior to develop and 

make available information concerning historic properties. Comments on the 

usefulness of this information and information on how to obtain copies may be 

directed either to the Chief, Preservation Assistance Division, ational Park 

Service, US. Department of the Interior, P.O. Bo, 37127, Washington, D.C. 20013-

7127, or to the Director, Technical Preservation Services Center, New York 

Landmarks Conservancy, 141 Fifth Avenue, New York, NY IDOlO. 

This publication is not copyrighted and can be reproduced without p~nalty. 

Normal procedures for credit to the authors, the New York Landmarks 

Conservancy, and the National Park Service are appreciated. 

ISSN: 0885-7016 October 1991 

For sale by the Superintendent of Documents, U.S. Government Printing Office 

Washington, D.C. 20402