Features and Decay of Cast Stone Elements in New York City Buildings in Comparison with Cast Stone in Milan

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

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 varietyDRAFT 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 1

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

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 knownDRAFT 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

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

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)DRAFT 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 3

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

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. DRAFT 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

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

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 differentDRAFT 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 5

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

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 degradationDRAFT 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 6

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

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 Staten Isl. 1930 Education 1 Hall Resurrection church Rye (NY) 1927 Worship 1 (Figs. 9,10)

DRAFT

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

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 Grain- Ground Aggregate Aggregate Sample Typology size colour composition morphology (mm) Waldorf Astoria 10YR 8/2 dolomite angular 2 - 4 W. Astoria 20th slab 10YR 8/2 dolomite angular 2 - 4 fl. 161 Hudson Str. coping 5PB 9/1 dol., coal angular 5 - 8 130 W 12th pillar 5Y 9/1 dol., coal angular 2 - 8 Street 130 W 12th coping 2.5YR 7/4 dolomite angular 2 - 5 Street 155 W 20th window 5R 9/2 dolomite angular 4 - 8 Street sill window 2 Grace Court 10YR 7/2 quartz, dol. sub-angular 10 sill St. Paul church spire 5Y 8.5/1 dolomite angular 3 - 5 Wagner college cornice 10YR 8/2 dol., quartz angular 1 - 2

DRAFT Ext. layer window 10YR 8/2 quartz rounded 0.2-0.5

Mid layer surroundin 10YR 7/1 quartz, feld. subrounded 1 – 5 ection Resurr Bulk gblock 10YR 7/2 quartz, dol. subangular 1 – 8

Table 4a. Sample analyses - Milan Ground Aggregate Aggregate Grain-size Sample Typology colour composition morphology (mm) Former Stock ex. slab 5YR 7/4 calcite angular 0.3 - 0.5 10YR Politecnico #1 slab gneiss, lim. angular 0.2 – 4.0 6/1 10YR Politecnico #2 window sill gneiss, lim. angular 0.5 – 12 7/2 Politecnico #3 window sill 10YR quartz rounded 0.2 – 8.0

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

7/2 10YR Politecnico #4 slab lim., gneiss angular 0.2 – 9.0 7/2 10YR limest, Politecnico #5 baluster angular 0.4 – 4.0 7/2 dolom. limest., St Gregorio #6 angular 0.2 - 1.2 calcite frieze 2.5Y 7/2 dolo., lim., St Gregorio #7 rounded 0.2 - 3.0 qtz 10YR Petrarca slab gneiss angular 0.2 - 3.6 7/1 Boccaccio #1 slab 10R 5/4 limestone angular 0.2 - 2.2 10YR Boccaccio #2 balustrade limestone angular 0.4 - 4.0 7/2 10YR Boccaccio #4 frieze limestone angular 0.5 - 3.5 7/1 10YR Boccaccio #5 slab limestone angular 0.2 - 4.5 7/1

Table 4b. Sample analyses - Lombardy villa Gajo #1 pillar 10YR 7/1 limestone angular 0,5 - 3.5 marble, black villa Gajo #2 ornament 10YR 6/1 angular 0.2 - 5.0 limestone marble, black villa Gajo #3 ornament 10YR 7/1 angular 0.4 - 5.0 limes., quartz Donizetti #2 extern. 5YR 7/4 limestone angular 0.1 - 1.0 cornice 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 lim., gneiss, T. Donizetti #4 pediment 10YR 7/1 rounded 0.3 - 2.0 flint 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 slabDRAFT 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.

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

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 aboutDRAFT 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.

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

Fig. 1 - Faux granite (below) and fine grained Fig. 2 - Tracery at Resurrection Church (Rye, slabs NY)

Fig. 3 - Parabiago (Milan) Villa Gajo cast Fig. 4 - Parabiago (Milan) Villa Gajo, detail stone units DRAFT

Fig. 5 – Erosion of cementitious matrix Fig. 6 – Effects of aggressive cleaning (unprotected elements on the right) due to rain methods (Rye) wash-out

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

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) DRAFT

Figs. 11 and 12 - Teatro Donizetti (Bergamo): red limestone clasts (external); quartz - limestone sand (core)

12th International Congress on the Deterioration and Conservation of Stone Columbia University, New York, 2012

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).

DRAFT