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12th International Congress on the Deterioration and Conservation of Stone
Columbia University, New York, 2012
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FEATURES AND DECAY OF CAST STONE ELEMENTS IN NEW YORK
CITY BUILDINGS IN COMPARISON WITH CAST STONE IN MILAN
Roberto Bugini1, Mariachiara Faliva2 and Luisa Folli3
1 CNR – ICVBC, Istituto per la Conservazione e la Valorizzazione dei Beni
Culturali, via Roberto Cozzi 53, 20145 Milan (Italy)
2 Thornton Tomasetti, Inc., 51 Madison Avenue, New York, NY 10010 (USA)
3 Independent Researcher, viale Calabria 18/B, Lodi (Italy)
Abstract
Cast stone was a new construction material introduced in the second half of
the 19th century for the production of architectural elements such as sills, window
frames, cornices, ornamentations, statues; technological advances allowed use of
this material for complicated shapes with considerable savings in costs compared to
carved natural stone. Cast stone use followed similar patterns in North America and
Europe. This paper compares and contrasts production and performance of this
innovative material between two countries by analyzing material samples from
historic structures in New York and Milan. Samples dating to the first decades of
the 20th century were analyzed using petrographic methods. Samples were described in terms of aggregate composition, aggregate grain size and binder colour.
The main decay observed was surface erosion of the cementing matrix. This decay
can be attributed to exposure to the elements and pollution, but can be accelerated
by the type of tooling used to finish the cast stone surface.
Keywords: cast stone, artificial stone, New York City, Milan
1. Introduction
Since the first half of the 19th century improvements in material science
studies and technologies led to many attempts at finding new and better methods of
construction. One of the outcomes of these experiments was the introduction of the
first modern hydraulic cements, above all Portland cement 1. A natural consequence was the production of “artificial stone,” a mix of cement and lime in various forms
and recipes with a variety of aggregates, formed in blocks or other decorative
elements. Throughout the second half of the 19th century various attempts were
made in different European countries and in USA to produce artificial stone.
François Coignet in France was one of the pioneers in this field and started
producing concrete or béton aggloméré by mixing Portland cement, lime, hydraulic
lime, and aggregate (Gilmore 1871: 1-73). Cast stone, especially in block form,
started to introduce a new way of building based on some desirable and useful
characteristics: it permitted faster construction and it provided fire protection,
reducing production and construction costs. Initially used mainly for these reasons,
starting from the 20th century cast stone, also known as “artificial stone” or “concrete stone”, increased in popularity due to two of its most valuable features:
efficient production of repetitive pieces using industrial processes and the ability to
provide custom finishes. It eventually gained acceptance equal to natural stone,
when architects decide to use cast stone elements throughout buildings. Cast stone
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was used not only for sills, window frames and cornices, but also for statues,
elaborate ornamentation and pinnacles. Symptomatic of the new role and perception
acquired by cast stone in the 20th century is an article by Henry P. Warner,
president of one of the main manufacturers of cast stone 2, published in 1927 on the
journal of the American Concrete Institute: “there is a rapidly increasing number of
architects and engineers who are now using the product because of its merits and
because they find that they need it and that it has qualities which make it valuable”
(as opposed as its mere inexpensiveness), and again “our company is in the
production of a material which does not in any way resemble any particular natural stone”.
The popularity of cast stone was not limited to the United States or France: a
similar pattern occurred in Italy where cast stone composition, texture, grain-size,
color and surface tooling first tried to imitate architectural elements made of natural
stone, but then acquired its own individuality. This study compares production and
use of this innovative material in the United States and in Italy by analyzing
samples from 20th century buildings in New York, Milan and Lombardy; it takes
into account ashlars, blocks for ornamental purposes as well as slabs used for
veneers.
2. Cast stone production and use in two cities
2.1 Examples from New York
Early known as artificial stone, the use of cast stone construction elements
spread from the USA from the second half of the 19th century. Various attempts
were made by using a variety of recipes, mostly including hydraulic and hydrated
lime and local natural cements because imported Portland and natural cements from
Europe were still very expensive (Gilmore 1871: 49 and Jester 1995: 87).
Development of artificial stone manufacturers occurred on the West cost of the
United States (mainly the Bay Area) as well on the East coast, being more
numerous in the Northeast due to natural cement quarries and producers in the
vicinity and harbours to which Portland cement was shipped from Europe (Tomlan
1974: 5). An early example was Frear stone, patented by George Frear of Chicago
in 1868, a mix of hydraulic cement, aggregate and shellac; around the same time the American Building Block Company was producing blocks made of common lime
and aggregate, also known as Foster process, while Sorel’s artificial stone was
manufactured by Union Stone Company in Boston, developed in 1853 based on
experimentation by the French chemist Sorel who added hydraulic cement to the
mix. In 1868 the Pacific Stone and Concrete Company in San Francisco was
producing calcium silicate based blocks under the patent of the Englishman
Frederick Ransome while the New York and Long Island Coignet Stone Company
produced artificial stone based on the French recipe (Jester 1995: 87-88, Pieper: 1-3,
Prudon 1989: 81-84 and Tomlan 1974) 3. Cast stone manufacturing started with
production of simple concrete blocks. These first attempts had no aesthetic
ambitions and were cast as solid or hollow blocks. Poor quality and failures also characterized this period (Whipple 1915: 9-10 and Gillespie 1979: 30). By the
beginning of the 20th century the production of domestic Portland cement, the
decrease in price of imported cement and the proven higher quality of cement had
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the effect of abandoning early mixes. This also made the full development of the
cast stone industry possible.
Cast stone was produced following three main methods: the tamped process,
in which the element was cast using a mix of dry consistency and removed from the
mould right after; the pressed process which used a slightly more fluid mix pressed
by heavy machinery into moulds; and the wet process in which a very fluid mix was
poured into moulds and allowed to cure completely. Although more expensive, the
wet process was considered the best practice because the units produced with this
method were claimed to achieve more strength, increased hardness and improved water tightness 4. To obtain the desired appearance various surface treatments were
employed, including abrading the surface on special rubbing beds, tooling using the
same traditional tools used for natural stone such as points and variously shaped
chisels, and etching the surface by applying or immersing the element in a solution
of hydrochloric acid and water. Dry-tamped cast stone presented a surface requiring
less work to expose the aggregate, while cement and aggregate fines had to be
removed to expose the aggregate in wet-cast units. A smooth surface was referred to
as Terrazzo texture5. Sand moulds were used to give a smooth, sandy appearance to
the unit (Havlik 1927: 213) as well as to regulate water absorption during the curing
process (Whipple 1915: 113). Colour was obtained by using coloured stones as
aggregate and pigments in the bulk cement. The main stone used was ground marble which, combined with black copper slag, was intended to replicate granite
(Figure 1). Natural granite was also used as aggregate, sometimes with the granite
imparting its natural colour. To reduce costs, a common practice was to pour in the
mould a first layer (called facing, typically 3/4" to 1 ½" thick or 2 - 4 cm) of cement
and costly aggregate and pigments and to fill the remaining portion with a less
expensive, coarser mix that would not be exposed to view (Whipple 1915: 126) (Fig.
2).
2.2 Examples from Milan and Lombardy
Since the mid-19th century the increase of the cost of stone supply and of
stone working encouraged the exploitation of a new material with the same strength
of the natural stone but easier to shape in different forms and considerably less expensive. The material called pietra artificiale (artificial stone) or cemento
decorativo (decorative cement) was made directly on site using moulds made of
wood, metal, gypsum or glue. On the contrary, other artificial materials (brick,
terracotta) needed factories using expensive machinery. The first cast stone attempts
were made using hydraulic lime or magnesium-based lime or gypsum as binders,
but the poor results in terms of durability redirected the manufacturers to use
Portland cement-based binders. The best results were obtained by Società Italiana
dei Cementi e delle Calci Idrauliche (established 1854 in Bergamo) using a
Portland cement called Cemento Portland naturale, which used Cretacic marly
limestones quarried in Val Seriana (Scanzo, Villa di Serio, Comenduno,
Pradalunga), some kilometers north of Bergamo. The Portland cement binder was mixed with different kinds of aggregate to obtain a material with good mechanical
properties and able to match the appearance of natural stone; great care was devoted
to the preparation of individual components (Fumagalli 1964, 13-62). The firm
Fratelli Pesenti, established 1878 in Alzano (Bergamo), produced since 1894 a
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white artificial stone called Cemento bianco (white cement), a perfect imitation of
the pure white marble from Carrara, an expensive material traditionally employed
for sculpture and decorative works. The recipe involved the addition of white
limestone and kaolin together with calcium or sodium fluoride, borax or leucite
(potassium - aluminium silicate); these components, used as flux, reduced the
presence of calcium-iron-aluminium oxide which causes the gray colour typically
seen in cement (Carlessi 2001). Other recipes include marble, gypsum and kaolin
(Ghersi 1915: 171-177). An iron-free white Portland cement with calcium carbonate
and white clay was reported from the USA (Il Cemento 1907: 110). The use of pietra artificiale had been such a distinctive character of the
Milanese architecture at the turn of 19th century (Bairati 1985: 72-89 and Gramigna
2001: 8-75) that many architects and builders almost completely neglected the use
of natural stone (Figures 3, 4). This change caused the abandonment of a great
number of quarries, such as those in Viggiù. In fact, artificial stone perfectly
matched the colour and the texture of the brown oolithic limestone from Viggiù
previously employed to make carved ornaments or sculptures. After centuries of
supplying materials for buildings throughout Lombardy, the Viggiù workers left to
North America, where they exploited the granite quarries in Vermont (Washington
County) (Caravatti 1925: 73-77). The pietra artificiale was employed for mouldings
around windows and doors, balcony balustrades, cornices, bases and capitals; in many cases the excess of ornamentation caused a censure by other architects
(Beltrami 1906: 104). Ornamental schemes came from architectural tradition
(geometric shapes, volutes, masks, human figures) but also new sources of
inspiration were chosen from the botanical and zoological world (leaves of chestnut
or wisteria or vines; heads of lions or eagles or fantastic animals, etc.) or from the
achievements of the mechanical industry (Colombo 1985). In some cases the
ornaments reflected the items produced in the same building: i.e. the office building
of the steam locomotive factory Società Italiana Carminati & Toselli (1911) shows
window frames decorated with train wheels, bumpers, chains and leaf springs. The
pietra artificiale was also applied for veneers and using artificial elements bigger
than a stone slab; orthogonal cuts were made to replicate joints, while the surface
tooling was made employing same tools (chisel, bush hammer) used for natural stone.
3. Analyses
3.1 Sampling
Samples were taken from buildings of some of the New York boroughs (Table
1) and from Stile Floreale or Art Nouveau buildings of Milan and Lombardy (Table
2), all dating to the first decades of the 20th century. Buildings sampled refer to
different types: private dwellings, public buildings for business, education or
recreation or religious buildings. In many cases only one sample was chosen. In
other cases the samples were taken from different parts of the building. While
innumerable recipes to make artificial stone were reported in engineering papers and treatises, detecting a particular recipe in sampled material is very difficult, especially
regarding the proportions of different components. Although Italian and American
technical magazines communicated with accuracy the status of research and
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achievements in Europe and the US, it is difficult to confirm the real transfer of the
research and achievements in the final installed products.
3.2 Methods of Analyses
Petrographic methods (optical microscopy and powder x-ray diffraction) were
used in order to perform a great number of analyses at reasonable cost.
Optical microscopy on thin section: the samples were prepared following the
standard method: impregnation of the specimen with an organic resin, mounting on a
glass slide, sawing and grinding to the required thickness, covering with glass; viewing by Nikon Eclipse E400 Pol microscope with Nikon Pol objectives.
X-ray diffraction on powder: the samples were prepared as follows: dry
pulverization in agate mortar and pestle and specimen mounting on a dimpled glass
holder. The instrument was a PANalytical X’Pert PRO MPD with generator
settings 40mA / 40kV -CuKa with λ=1.5406 Å, scan range 3-75°, 2θ -step size
0.017, 2θ -scan step time 10.3376 s, continuous scan type. Analysis software was
PANalytical X’Pert HighScore. Petrographic analyses permitted identifying
aggregate characteristics including mineralogical composition, grain morphology
and grain size. These are the most important features for comparing different
samples to highlight similarity or dissimilarity.
4. Results and Discussion
4.1 New York (Table 3)
Similar characteristics were observed across various samples, despite their
different typology. The grain-size is always coarse, with clasts ranging from 1 to 10
mm. A common component of the aggregate is dolomite in angular-shaped clasts.
Dolomite is present in many white marbles coming from different States and used
quite often in New York buildings: a comparison among quarry samples would be
needed to identify the provenance. Coal slag clasts are another relevant component,
confirming the practice of mimicking granite by using marble and slag: the first one
to imitate the feldspar crystals, the second one to imitate the biotite lamellae. The most interesting is the case of Resurrection church (Rye) where is evident the
presence of three different mortars: the external one (10 mm thick) is made of fine
grained rounded crystals of quartz, the middle one (5 mm thick) is made of quartz
and coarse grained feldspar, the core is made of a coarse grained and poorly sorted
mix of metamorphic rock fragments together with dolomitic rock fragments. The
layers are distinctly separated and their differences are also enhanced by different
colour saturation. This is an example of the method involving the filling of the mould
with different kind of mortars: finer outside, coarser inside (Figure 1).
4.2 Milan (Table 4a) and Lombardy (Table 4b)
The Milanese samples also exhibit similar features despite the different typologies represented. Maximum grain-size is almost always smaller than 5 mm. A
common component of the aggregate is calcite: the morphology of the clasts may
support a provenance from the local limestones. In only one case, the former Stock
Exchange (1901), calcite crystals are present in the aggregate as detected in Roman
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painted plasters or in Renaissance stucco works. Another component is a sand
(quartz, metamorphic rocks, limestone, flint) reflecting the lithology of alpine and
prealpine rocks outcropping in Lombardy and carried by local rivers. The imitation
of granite was made using white limestone clasts to imitate feldspar and black
limestone clasts to imitate biotite; both white and black Mesozoic limestone is
present throughout the Lombard Prealps. The cemento bianco, employed in Oratorio
Pesenti (Montecchio), presents some distinctive features: ornamental elements, such
as pinnacles, contain angular shaped dolomite clasts and calcite crystals; slabs, on
the contrary, contain river sand (rounded clasts of quartz and limestone). Italian magazines (Il Cemento 1908: 17-18) reported a method similar to the one used at
Rye: use of this method was detected in the cornice of Teatro Donizetti with Red
Ammonitic limestone clasts in the external mortar and river sand in the core.
5. Phenomena and causes of decay
After about one century of exposure to weathering agents, cast stone elements
display various signs of decay. The most common phenomenon observed is surface
erosion of the cementitious matrix; this is more evident in the areas washed out by
rain; in some samples the aggregate was left exposed by several millimetres
(Biondelli et al. 2004) (Figure 5). Erosion can be attributed to exposure to the
elements and pollution, but overly aggressive tooling could have accelerated it. Some New York samples might have been subject to finishing processes that
involved brushing, water and acid washing of the not yet hardened cement surfaces,
in order to ablate the thin layer of cement: this kind of finishing enhanced the
morphology of the aggregate creating a surface resembling natural stone (Il
Cemento 1919: 113-114). In some of the samples a network of micro-cracks was
observed in the matrix; this is attributable to shrinkage of the mix. Another typical
condition detected was gypsum crust: it was observed on sheltered areas where
water droplets moisten the surface and facilitate the formation of the crust. Erosion,
corrosion and micro cracking also affect the aggregate, mostly the dolomitic grains.
In addition, fairly typical was the growth of living organisms (algae, lichens,
mosses), which easily propagate on the cast stone due to its porosity and surface
roughness. Rust spots caused by steel reinforcing, cramps or the presence of metal ornaments were also observed. Quite often, overly aggressive cleaning methods can
contribute to the degradation of the cast stone: sand blasting and power washing are
the main culprits but also milder treatments can be detrimental when incorrect
pressure and cleaning media are selected (Figure 6). A very peculiar “cleaning”
technique has been used recent years on Milan buildings: cast stone surfaces are
cleaned with water lances under high pressure or with wet sand blasting. Surfaces
are then coated with paints of colour to match the original ground colour of the
cement (grey, yellow or pink). Original colours, texture, and finishes are then
completely lost.
6. Conclusions The comparison among the samples analyzed permitted finding similarities and
differences between the artificial stone used in New York and the artificial stone
used in Milan. The binder for all the analyzed samples is Portland cement; however,
it was observed that the American stones are more variable in colour and use a
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wider range of yellow, red, pink pigments than the Italian ones, which are all gray.
The aggregate is the feature that best characterizes the samples and shows the
greatest differences. The American cast stone aggregates are coarser (up to 10 mm)
while the Italian ones are finer (less than 5 mm). Regarding grain morphology, in
both countries aggregates are made of crushed natural stone; in some cases (mostly
in the Italian samples) the roundness of the clasts attests the use of river sand.
Dolomite is quite ubiquitous in the American samples, while limestone is in the
Italian ones; black spots were made out of coal slags in America, instead black
limestone was used in Italy. Variations in aggregate colour can be equally found in both countries (black, red, white).
Although this study does not aim to exhaustively cover the many variations
that occurred in the production and use of cast stone in the two countries, its
intention is to start comparative studies of a material that became a very important
means of expression in the architectural language of the early 20th century.
Table 1. New York Samples 6
Building Location Year Building type Samples
Waldorf Astoria Manhattan 1931 Hotel 2 (Fig. 7)
161 Hudson Street Manhattan 1900 Residential 1
130 W 12th Street Manhattan 1940 Residential 2
155 W 20th Street Manhattan 1936 Residential 1 (Fig. 8)
2 Grace Court Brooklyn 1923 Residential 1
St. Paul church Staten Isl. 1915 Worship 1
Wagner Coll. Main
Hall Staten Isl. 1930 Education 1
Resurrection church Rye (NY) 1927 Worship 1 (Figs. 9,10)
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Table 2. Milan and Lombardy Samples
Building Location Year Building type Samples
Former Stock exch. Milano 1901 Business 1
Politecnico Milano 1925 Education 5
St Gregorio ch Milano 1908 Worship 2
via Petrarca 4 Milano 1903 Residential 1
via Boccaccio 27 Milano 1910 Residential 5
Villa Gajo Parabiago (MI) 1907 Residential 3
Teatro Donizetti Bergamo 1903 Theatre 4 (Figs 11,12)
Oratorio Pesenti Montecchio (BG) 1904 Worship 3 (Figs 13,14)
Villa Pesenti Montecchio (BG) 1897 Residential 1
Officina Pesenti Montecchio (BG) 1898 Industrial 1
Grande Albergo Campo Fiori (VA) 1911 Hotel 4
Table 3. Sample analyses - New York
Sample Typology Ground
colour
Aggregate
composition
Aggregate
morphology
Grain-
size
(mm)
Waldorf Astoria
slab
10YR 8/2 dolomite angular 2 - 4
W. Astoria 20th
fl. 10YR 8/2 dolomite angular 2 - 4
161 Hudson Str. coping 5PB 9/1 dol., coal angular 5 - 8
130 W 12th
Street pillar 5Y 9/1 dol., coal angular 2 - 8
130 W 12th
Street coping 2.5YR 7/4 dolomite angular 2 - 5
155 W 20th
Street
window
sill 5R 9/2 dolomite angular 4 - 8
2 Grace Court window
sill 10YR 7/2 quartz, dol. sub-angular 10
St. Paul church spire 5Y 8.5/1 dolomite angular 3 - 5
Wagner college cornice 10YR 8/2 dol., quartz angular 1 - 2
Res
urr
ecti
on
Ext. layer window surroundin
gblock
10YR 8/2 quartz rounded 0.2-0.5
Mid layer 10YR 7/1 quartz, feld. subrounded 1 – 5
Bulk 10YR 7/2 quartz, dol. subangular 1 – 8
Table 4a. Sample analyses - Milan
Sample Typology Ground
colour
Aggregate
composition
Aggregate
morphology
Grain-size
(mm)
Former Stock ex. slab 5YR 7/4 calcite angular 0.3 - 0.5
Politecnico #1 slab 10YR
6/1 gneiss, lim. angular 0.2 – 4.0
Politecnico #2 window sill 10YR
7/2 gneiss, lim. angular 0.5 – 12
Politecnico #3 window sill 10YR quartz rounded 0.2 – 8.0
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7/2
Politecnico #4 slab 10YR
7/2 lim., gneiss angular 0.2 – 9.0
Politecnico #5 baluster 10YR
7/2
limest,
dolom. angular 0.4 – 4.0
St Gregorio #6
frieze 2.5Y 7/2
limest.,
calcite angular 0.2 - 1.2
St Gregorio #7 dolo., lim.,
qtz rounded 0.2 - 3.0
Petrarca slab 10YR
7/1 gneiss angular 0.2 - 3.6
Boccaccio #1 slab 10R 5/4 limestone angular 0.2 - 2.2
Boccaccio #2 balustrade 10YR
7/2 limestone angular 0.4 - 4.0
Boccaccio #4 frieze 10YR
7/1 limestone angular 0.5 - 3.5
Boccaccio #5 slab 10YR
7/1 limestone angular 0.2 - 4.5
Table 4b. Sample analyses - Lombardy
villa Gajo #1 pillar 10YR 7/1 limestone angular 0,5 - 3.5
villa Gajo #2 ornament 10YR 6/1 marble, black
limestone angular 0.2 - 5.0
villa Gajo #3 ornament 10YR 7/1 marble, black
limes., quartz angular 0.4 - 5.0
Donizetti #2 extern. cornice
5YR 7/4 limestone angular 0.1 - 1.0
Donizetti #2 core 10YR 7/1 lim., gneiss, qtz rounded 0.2 - 3.0
T. Donizetti #3 bracket 5YR 7/4 limestone angular 0.1 - 2.2
T. Donizetti #4 pediment 10YR 7/1 lim., gneiss,
flint rounded 0.3 - 2.0
or. Pesenti #1 ornament 10YR 9/1 dol., calcite angular 0.2 - 2.0
or. Pesenti #2 plinth 10YR 9/1 dol., calcite angular 0.2 - 1.8
or. Pesenti #3 slab 10YR 9/1 quartz, limes. rounded 0.2 - 2.5
villa Pesenti #4 balustrade 10YR 8/1 marble angular 2.0 - 3.0
off. Pesenti #6 balustrade 10YR 7/1 limes., qtz, flint rounded 0.4 - 6.0
Gr. Albergo #1 ornament 10YR 7/2 limestone angular 0.4 - 3.6
Gr. Albergo #3 plinth 10YR 7/2 limestone angular 0.2 – 10
References
Bairati, E. and Riva, D. 1985. Il Liberty in Italia. Bari: Laterza.
Beltrami, L. (ed.) 1906. Milano nel 1906. Milano: Allegretti.
Biondelli, D., Bugini, R., Folli, L. and Saltari, V. 2004. “I materiali lapidei
nell’architettura del Novecento a Milano.”. In Architettura e materiali del
Novecento, Biscontin, G. (ed.) 57-66. Venezia: Arcadia Ricerche.
Caravatti, F. 1925. Viggiù nella storia e nell’arte. Varese: Arti grafiche varesine.
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Carlessi, M. and Bugini, R. 2001. “L’oratorio Pesenti in Montecchio”. In Lo stucco,
Biscontin G. (ed.) 469-482. Venezia: Arcadia Ricerche.
Colombo, C. 1985. “La stagione del cemento artistico a Milano”. In Costruire in
Lombardia: l’edilizia residenziale, Selvafonta, O. (ed.) 61-76. Milano: Electa.
Fumagalli, C. 1964. La Italcementi: origini e vicende storiche. Bergamo:
Italcementi.
Ghersi, I. 1915. Ricettario industriale. Milano: Hoepli.
Gillespie, A. 1979. “Early development of the “artistic” concrete block: the case of
the Boyd Brothers”. Bull. of the Assoc. for Preservation Technologies, 11(2): 30-52.
Gillmore, Q. A. 1871. A practical treatise on Coignet-Beton and other artificial
stone. New York: Van Nostrand.
Gramigna, S. and Mazza, M. 2001. Milano: un secolo di architettura milanese dal
Cordusio alla Bicocca. Milano: Hoepli.
Il Cemento, rivista tecnica dei materiali da costruzione. Milano, since 1904.
Jester, T. 1995. Twentieth-century building materials. New York: McGraw-Hill.
Pieper, R. sd. “The maintenance, repair and replacement of historic cast stone”.
Preservation Briefs, 42. National Park Service, U.S. Department of the Interior.
Prudon, T. 1989. “Simulating stone, 1860-1940: artificial marble, artificial stone,
and cast stone”. APT Bulletin, 21(3/4): 79-91. Tomlan, M. 1974. Cast stone: its history and use in the United States to 1914.
Unpublished manuscript.
Whipple, H. 1915. Concrete Stone manufacture. Detroit: Concrete-Cement Age
Publishing Co. Notes 1. The first version of Portland cement was patented in 1824 in Britain by Joseph Aspdin, a
British bricklayer from Leeds. It was produced from natural cements and was named based
on its similarity to the Portland Stone, a natural stone quarried on the Isle of Portland in England. The newly conceived production technique guaranteed a quick-setting and material with high compressive strength. Many attempts to produce cementitious materials had been carried out during the previous 100 years, all contributing to the final success, including efforts by John Smeaton, James Parker, James Frost and many others.
2. Onondaga Litholite Co., Syracuse, NY. 3. For more information about production of early artificial stone production see Pieper,
Prudon and Jester.
4. Robert F. Havlik, President and engineer of the Havlik Stone Co. in Aurora, Ill., discusses various aspects of the wet cast process in his paper published in the American Concrete Institute Journal in 1927.
5. Havlik, ibidem, Louis A. Falco “Recommended Practices in the Use of Cast Stone”, and Gilbert E. Tucker “Pacific Stone. A dry Tamped Product”, all published in the American Concrete Institute Journal between 1927 and 1930.
6. Some of the samples were kindly provided by Essex Works LTD and Architectural Molded Composites.
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Fig. 1 - Faux granite (below) and fine grained slabs
Fig. 2 - Tracery at Resurrection Church (Rye, NY)
Fig. 3 - Parabiago (Milan) Villa Gajo cast stone units
Fig. 4 - Parabiago (Milan) Villa Gajo, detail
Fig. 5 – Erosion of cementitious matrix (unprotected elements on the right) due to rain wash-out
Fig. 6 – Effects of aggressive cleaning methods (Rye)
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Figs. 7 and 8 - Dolomite crushed clasts at Waldorf Astoria (20th floor) and 155W 20th Street
(New York)
Figs. 9 and 10 - Resurrection church (Rye, NY): quartz crystals (external); gneiss clasts (core)
Figs. 11 and 12 - Teatro Donizetti (Bergamo): red limestone clasts (external); quartz - limestone sand (core)
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Figs. 13 and 14 - Oratorio Pesenti (Montecchio): dolomite clasts (ornament); sand aggregate (slab) Photos credits: Faliva (photos 1-2 and 5-6); Bugini and Folli (photos 3-4 and 7-14).