Development of a refractory mold based on chamotte/plaster for jewelry micro-casting with pre-set emeralds

Main Article Content


Carlina Sofía Londoño-Montes
Mayerly Jhojana Fernández-Torres
Elcy María Córdoba-Tuta


During the jewelry stone-in-place micro-casting process, the ceramic mold, which is composed of silica and plaster is stabilized at temperatures close to 650 °C, whereas the casting temperature of the precious metal alloy hovers around 1000 °C. Therefore, this type of micro-casting technique is not suitable for gems such as emeralds, since they are highly susceptible to damage at temperatures over 350 °C. In the face of this fact, the main purpose of the present work is to develop a refractory mold based on chamotte and plaster, which can be stabilized at low temperatures, in order to use it for the micro-casting of pre-set emeralds. To achieve this, the experimental methodology was divided into three phases: i) raw chemical materials, mineralogical, granulometric and thermal characterization; ii) preparation and characterization of chamotte-plaster-water mixtures, including the measurement of casting times, mechanical and microstructural properties, permeability, and resistance to thermal shock; and iii) evaluation of the resulting refractory mold in the micro-casting of pre-set emeralds. The results showed that the refractory mold with composition chamotte/plaster 75/25, an addition of 50 % of water to the dried mixture, and fine granulometry (-200 mesh) had a stabilization temperature of 350 °C. Furthermore, it is possible to subject the emeralds to the stone-in-place micro-casting process that employs the refractory mold developed here, with a thermal treatment that does not surpass the 350 °C, along with a low melting point (398 °C) for the precious metal alloy.


Article Details


All articles included in the Revista Facultad de Ingeniería are published under the Creative Commons (BY) license.

Authors must complete, sign, and submit the Review and Publication Authorization Form of the manuscript provided by the Journal; this form should contain all the originality and copyright information of the manuscript.

The authors who publish in this Journal accept the following conditions:

a. The authors retain the copyright and transfer the right of the first publication to the journal, with the work registered under the Creative Commons attribution license, which allows third parties to use what is published as long as they mention the authorship of the work and the first publication in this Journal.

b. Authors can make other independent and additional contractual agreements for the non-exclusive distribution of the version of the article published in this journal (eg, include it in an institutional repository or publish it in a book) provided they clearly indicate that the work It was first published in this Journal.

c. Authors are allowed and recommended to publish their work on the Internet (for example on institutional or personal pages) before and during the process.
review and publication, as it can lead to productive exchanges and a greater and faster dissemination of published work.

d. The Journal authorizes the total or partial reproduction of the content of the publication, as long as the source is cited, that is, the name of the Journal, name of the author (s), year, volume, publication number and pages of the article.

e. The ideas and statements issued by the authors are their responsibility and in no case bind the Journal.


H. Schuster, “Problems, causes and their solutions on stone-in-place casting process: latest developments”, in Santa Fe Symposium, Albuquerque, EE.UU., pp. 315-321, 2000.

I. Mckeer, “Stone-in-place casting: the investment perspective”, in Santa Fe Symposium, Albuquerque, EE.UU., pp. 293-314, 2004.

H. Shuster, “Stone-In-Place Casting for High-End Jewelry,” in Santa Fe Symposium, Albuquerque, EE.UU., pp. 283-294, 2008.

J. Daza, Estudio de las variables determinantes en la tolerancia de las esmeraldas colombianas al método de gemas pre-engastadas para el proceso de microfundición, M.Sc. Thesis, Escu. Ing. Metal., UIS, Bucaramanga, Colombia, 2015.

E. Gavrilenko, Condiciones de formación y caracterización comparativa con las esmeraldas de otros orígenes, Ph.D. Thesis, Dept. Ing. Geol., Univ. Polit. Mad., Madrid, Spain, 2003.

C. Aurisicchio, O. Grubessi, and P. Zecchini, “Infrared spectroscopy and crystal chemistry of the beryl group,” The Can. Mine., vol. 32, p. 55, 1994.

G. R. Rossman, “Joaquinite: The Nature of its Water Content and the Question of Four-Coordinated Ferrous Iron,” Amer. Miner., vol. 60, pp. 435-440. EE.UU., 1975.

J. C. Zwaan, “Gemmology, geology and origin of the Sandawana emerald deposits, Zimbabwe,” Scr. Geol., vol. 131, pp. 1-211, 2006.

D. M. Adams, and I. R. Gardner, “Single-crystal vibrational spectra of beryl and dioptase,” J. Chem. Soc., Dalton Trans., vol. 14 (14), pp. 1502-1505, 1974. DOI:

R. D. Aines, and G. R. Rossman, “The high temperature behavior of water and carbon dioxide in cordierite and bervl,” Amer. Min., vol. 69, pp. 319-327, 1984.

G. Giuliani, C. France-Lanord, J. L. Zimmermann, A. Cheilletz, C. Arboleda, B. Charoy, P. Coget, F. Fontan, and D. Giard, “Fluid Composition, δD of Channel H2O, and δ18O of Lattice Oxygen in Beryls: Genetic Implications for Brazilian, Colombian, and Afghanistani Emerald Deposits,” Inter. Geo. Rev., vol. 39 (5), pp. 400-424, May. 1997. DOI:

M. Kolli, M. Hamidouchea, G. Fantozzib, and J. Chevalierb, “Elaboration and characterization of a refractory based on Algerian kaolin,” Cera. Inter., vol. 33 (8), pp. 1435-1443, Dec. 2007. DOI:

V. Lee, and T. Yeh, “Sintering effects on the development of mechanical properties of fired clay ceramics,” Mat. Scie. and Engi., vol. 485 (1-2), pp. 5–13, Jun. 2008. DOI:

Y. Kobayashi, O. Ohira, Y. Ohashi, and E. Kato, “Effect of firing temperature on bending strength of porcelains for tableware,” Jou. of the Ame. Cera. Soc., vol. 75 (7), pp. 1801-1806, Jul. 1992. DOI:

C. Londoño, Diseño de un procedimiento de fabricación del revestimiento refractario para adaptar el método de gemas pre-engastadas a las esmeraldas colombianas, M.Sc. Thesis, Escu. Ing. Metal., UIS, Bucaramanga, Colombia, 2016.

R. Carter, “¿Does investment permeability impact jewelry castings?,” in Santa Fe Symposium, Albuquerque, EE.UU., pp. 105-119, 2004.

ASTM, Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates, ASTM C136/C136M – 14, 2014.

R. Carter, “Effects of changing the water to powder ratio on jewelry in investments,” in Santa Fe Symposium, Albuquerque, EE.UU., pp. 31-47, 2001.

H. Chattopadhyay, “Estimation of solidification time in investment casting process,” Adva. Manu. Techn., vol. 55 (1-4), pp. 35-38, Jul. 2010, DOI:

ASTM, Standard Test Methods for Physical Testing of Gypsum, Gypsum Plasters and Gypsum Concrete, ASTM C 472-99, 2014.

American Fuondry Society INC., Manual de arenas para fundición, Schaumburg, 1967, pp. 11-12, 29-42.

ASTM, Standard Test Method for Quantitatively Measuring the Effect of Thermal Shock and Thermal Cycling on Refractories, ASTM C1171 – 05, 2011.

M. Fernández, Obtención de una aleación preciosa de bajo punto de fusión para uso en el proceso de micro-fundición con esmeraldas colombianas pre-engastadas, M. Sc. Thesis, Escu. Ing. Metal., UIS, Bucaramanga, Colombia, 2016.

A. Luikov, A. G. Shashkov, L. L. Vasiliev, and Y. E. Fraiman, “Thermal conductivity of porous systems,” Inter. Jour. of Heat Mass Tran., vol. 11 (2), pp. 117-140, Feb. 1968. DOI:

C. Schacht. Refractories Handbook”, Ed. Boca Ratón, FL: CRC Press, 2004.

S. J. Stevens, R. J. Hand, and J. H. Sharp, “Polymorphism of silica,” Jour. Mat. Scie., vol. 32 (11), pp. 2929-2935, 1997. DOI:

R. Loewen, “The effect of Additives on the High Temperature Chemistry of Investment Materials,” in Santa Fe Symposium, Albuquerque, EE.UU., pp. 181-204, 1999.

Z. Aljubouri, and A. Al-Rawas. “Physical Properties and Compressive Strength of the Technical Plaster and Local Juss,” Iraqi Journal of Earth Sciences, vol. 9 (2), pp. 49-58. 2009.

J. Chan, et al. “Water of Hydration Dynamics in Minerals Gypsum and Bassanite: Ultrafast 2D IR Spectroscopy of Rocks,” Jour. of the Amer. Chem. Soc., vol. 30, pp. 9694-9703, 2016. DOI:

R. Carter, “Effects of changing the water-to-powder ratio on jewelry investments,” in Santa Fe Symposium, Albuquerque, EE.UU., pp. 30-47, 2001.

C.A. Strydom, et al, “The thermal dehydration of synthetic gypsum,” Elsevier, vol. 269-270, pp. 631-638, 1995. DOI:

W. Luk, and B. Darvell, “Effect of burnout temperature on strength of gypsum-bonded investments,” Elsevier, vol. 19, pp. 552-557, 2003. DOI:

S. Pattnaik, D. Benny Karunakar, and P. K. Jha, “Developments in investment casting process - A review,” Jour. of Mat. Proce. Techn., vol. 212 (11), pp. 2332-2348, Nov. 2012. DOI:

A. Kolomeisky, and S. Kazantsev, “Physycal-chemical analysis of the factors influencing the behavior of flasks during heating in the jewelry casting process. Development of the optimal model of burnout furnace,” in Santa Fe Symposium, Albuquerque, EE.UU., pp 253-264, 2004.

B. Yaman, and M. Cigdem, “Effect of particle size variations of gypsum bonded investment powders on metallurgical quality of investment castings,” Inte. Jour. of Cast Met. Rese., vol. 23 (1), pp. 60-65, Feb. 2010. DOI:

C. Schacht, Refractories Handbook, CRC Press, 2004. ISBN 9780824756543.

P. Horton, “Investment Power Technology – The present and the future,” in Santa Fe Symposium, Albuquerque, EE.UU., pp. 213-239, 2001.

M.M.A. Rafique, and J. Iqbal. “Modeling and simulation of heat transfer phenomena during investment casting”, International Journal of Heat and Mass Transfer, vol. 52 (7-8), pp. 2132-2139, Mar. 2009. DOI:

P. Dubois, et al. “Temperatura measurements in mold cavities during vacuum-assisted, static pouring of 14 yellow gold”, in Santa Fe Symposium, Albuquerque, EE.UU., pp. 131-156, 2002.


Download data is not yet available.