Sandra Zetina Ocaña | UNAM Universidad Nacional Autónoma de México (original) (raw)

Papers by Sandra Zetina Ocaña

International Journal of Polymer Analysis and Characterization, May 5, 2017

A large part of Mexican artistic heritage was created with artist's acrylic emulsion paints, so i... more A large part of Mexican artistic heritage was created with artist's acrylic emulsion paints, so it is crucial to investigate their composition, behavior and decay. Acrylic films are complex chemical systems combining organic and inorganic compounds; therefore, the degradation studies require a variety of techniques. We characterize three acrylic films before and after UV ageing. The relative composition of the polymer matrix was studied by nuclear magnetic resonance (NMR), pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and mass spectrometry with direct analysis in real time (DART-MS).The inorganic compounds and surfaces were characterized by microscopic techniques, such as digital microscopy (DM), scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS) and micro X-Ray diffraction (-XRD).The combined use of these techniques proved to be effective for an in-depth study of the acrylic painting degradation process. The main results were the gradual degradation for the organic surfactant and the loss of inorganic aggregates (talc and carbonates), that led to the Extensive studies on the identification and characterization of these emulsions have been carried out. [3,4,5,6] The two main analytical techniques used were FTIR [7] and Py-GC-MS. [ Error! Bookmark not defined. ] Other less commonly used techniques are the direct thermally-resolved mass spectroscopy (DTMS) [8] and NMR, [ Error! Bookmark not defined. ] the last being ideal for the identification of organic molecules in such paint materials. The surfactants are generally present in low concentrations and they can be either anionic(e.g., sodium lauryl sulfate), cationic(usually based on quaternary ammonium compounds), or nonionic (e.g., alkyl phenol ethoxylates). Non-ionic surfactants, especially those based on polyethoxylates, have been studied in recent years, primarily by their migration to the film surface causing changes in gloss and surface roughness. [9] The main analytical techniques for their study are MS-based techniques, [10,11] several FTIR-based techniques [9,12] and Py-GC/MS. [ Error! Bookmark not defined. ] Many of the artworks with pigmented acrylic emulsions are in outdoor spaces,where ultraviolet (UV) light has an important effect on their photo-oxidative stability. [13,14,15,16] We present the results of a study of three acrylic films,before and after accelerated ageing,by the combined use of techniques: NMR,Py-GC-MS,DART-MS,DM, SEM-EDSand-XRD. EXPERIMENTAL Chemicals / Materials Two of the most used colors in Mexico artworks were chosen: the Toluidine Redand the Hansa Yellow (Politec, Mexico), as well as the unpigmented acrylic binderlike Primal® AC33, (Santiago arte conservación y restauración, Mexico).

APS Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2019

Bulletin of the American Physical Society, Nov 19, 2012

techniques through empirical experimentation of modern and industrial materials and tools. Among ... more techniques through empirical experimentation of modern and industrial materials and tools. Among the young artists attending the workshop was Jackson Pollock. They tested different lacquers and a number of experimental techniques. One of the techniques, named by Siqueiros as a "controlled accident," consisted in pouring layers of paint of different colors on top of each other. After a brief time, the paint from the lower layer emerged from bottom to top creating a relatively regular pattern of blobs. This technique led to the creation of explosion-inspired textures and catastrophic images. We conducted an analysis of this process. We experimentally reproduced the patterns "discovered" by Siquieros and analyzed the behavior of the flow. We found that the flow is driven by the well-known Rayleigh Taylor instability: different colors paints have different densities; a heavy layer on top of a light one is an unstable configuration. The blobs and plumes that result from the instability create the aesthetically pleasing patterns. We discuss the importance of fluid mechanics in artistic creation.

MRS Proceedings, 2012

Xavier Guerrero (1896-1974) had an important role in the so-called Mexican Mural Renaissance, as ... more Xavier Guerrero (1896-1974) had an important role in the so-called Mexican Mural Renaissance, as a technical leader in the murals painted by Roberto Montenegro and Diego Rivera in the early 1920's. Jean Charlot, Diego Rivera and David Alfaro Siqueiros considered him as a sophisticated fresco craftsman, whose knowledge came from a popular mural painters guild. In 1941 the Mexican Government donated a School to Chillan, a Chilean town almost destroyed by a strong earthquake. David Alfaro Siqueiros and Xavier Guerrero were commissioned to paint murals on the Mexico School. Between 1941-1942 Guerrero decorated several walls and the staircase ceiling, the mural program is called De México a Chile (From Mexico to Chile). In 2010 another earthquake destroyed part of the ceiling. This study is part of the diagnosis project of De México a Chile, and consists in the characterization of the mortar and painting layers with optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis (TGA), while textural properties of the mortars were studied with nitrogen adsorption-desorption techniques. Analytical results show a stratigraphic sequence composed of several layers of Portland and lime combinations, and also an interesting painting technique that possibly involves the Portland cement setting process, with the development of specular gypsum.

Molecules, Jan 5, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

PLOS ONE, Oct 30, 2019

Jackson Pollock's most celebrated abstract paintings were produced with the so-called dripping te... more Jackson Pollock's most celebrated abstract paintings were produced with the so-called dripping technique. By pouring liquid paint with the help of a stick or from a can, Pollock deposited viscous fluid filaments on a horizontal canvas, rhythmically moving around it. The intricate webs of lines, ubiquitous in his compositions, have fascinated art historians and scientists. Based on image analysis of historical video recordings, we experimentally reproduced the painting process. We conclude that Pollock avoided the appearance of the hydrodynamic instabilities, contrary to what was argued by previous studies. Pollock selected the physical properties of the paint to prevent filament fragmentation before deposition, and applied it while moving his hand sufficiently fast and at certain heights to avoid fluid filaments from coiling into themselves. An understanding of the physical conditions at which these patterns were created is important to further art research and it can be used as a tool in the authentication of paintings.

Springer eBooks, Oct 29, 2010

arXiv (Cornell University), 2014

This is an entry for the Gallery of Fluid Motion of the 65st Annual Meeting of the APS-DFD (fluid... more This is an entry for the Gallery of Fluid Motion of the 65st Annual Meeting of the APS-DFD (fluid dynamics video). This video shows an analysis of the 'accidental painting' technique developed by D.A. Siqueiros, a famous Mexican muralist. We reproduced the technique that he used: pouring layers of paint of different colors on top of each other. We found that the layers mix, creating aesthetically pleasing patterns, as a result of a Rayleigh-Taylor instability. Due to the pigments used to give paints their color, they can have different densities. When poured on top of each other, if the top layer is denser than the lower one, the viscous gravity current undergoes unstable as it spread radially. We photograph the process and produced slowed-down video to visualize the process.

Conferencia /// Coloquio: 60 Anos de la construccion de CU.Un material perdurable, perpetuo e inm... more Conferencia /// Coloquio: 60 Anos de la construccion de CU.Un material perdurable, perpetuo e inmortal; los problemas de la tecnica en el muralismo a exterior y la integracion plastica. Mtra. Sandra Zetina Ocana. Instituto de Investigaciones Esteticas. UNAM. UNAM. 26 de noviembre de 2012. ///Universidad Nacional Autonoma de Mexico, Facultad de Filosofia y Letras, Posgrado de Historia del Arte, Taller de Integracion Plastica. //// Audio. Duracion: 44 minutos. //// Descarga: Pulse boton derecho del raton sobre el archivo de audio "mp3" que elija y seleccione "Guardar Destino Como...

Arqueología Mexicana, 2015

Intervención, May 1, 2010

Arqueología Mexicana, 2015

Arqueología Mexicana, 2018

Llega ahor aa su quinta decada al debate sobre el Codice Grolier considerado por algunos el cuart... more Llega ahor aa su quinta decada al debate sobre el Codice Grolier considerado por algunos el cuarto codice maya y por otros una mera falsificacion. El proposito de este articulo no es tomar partido por alguna de las posturas, sino mostrar los argumentos materiales que ponen en duda su autenticidad y que no han sido explicados certeramente

International Journal of Polymer Analysis and Characterization, May 5, 2017

A large part of Mexican artistic heritage was created with artist's acrylic emulsion paints, so i... more A large part of Mexican artistic heritage was created with artist's acrylic emulsion paints, so it is crucial to investigate their composition, behavior and decay. Acrylic films are complex chemical systems combining organic and inorganic compounds; therefore, the degradation studies require a variety of techniques. We characterize three acrylic films before and after UV ageing. The relative composition of the polymer matrix was studied by nuclear magnetic resonance (NMR), pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) and mass spectrometry with direct analysis in real time (DART-MS).The inorganic compounds and surfaces were characterized by microscopic techniques, such as digital microscopy (DM), scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS) and micro X-Ray diffraction (-XRD).The combined use of these techniques proved to be effective for an in-depth study of the acrylic painting degradation process. The main results were the gradual degradation for the organic surfactant and the loss of inorganic aggregates (talc and carbonates), that led to the Extensive studies on the identification and characterization of these emulsions have been carried out. [3,4,5,6] The two main analytical techniques used were FTIR [7] and Py-GC-MS. [ Error! Bookmark not defined. ] Other less commonly used techniques are the direct thermally-resolved mass spectroscopy (DTMS) [8] and NMR, [ Error! Bookmark not defined. ] the last being ideal for the identification of organic molecules in such paint materials. The surfactants are generally present in low concentrations and they can be either anionic(e.g., sodium lauryl sulfate), cationic(usually based on quaternary ammonium compounds), or nonionic (e.g., alkyl phenol ethoxylates). Non-ionic surfactants, especially those based on polyethoxylates, have been studied in recent years, primarily by their migration to the film surface causing changes in gloss and surface roughness. [9] The main analytical techniques for their study are MS-based techniques, [10,11] several FTIR-based techniques [9,12] and Py-GC/MS. [ Error! Bookmark not defined. ] Many of the artworks with pigmented acrylic emulsions are in outdoor spaces,where ultraviolet (UV) light has an important effect on their photo-oxidative stability. [13,14,15,16] We present the results of a study of three acrylic films,before and after accelerated ageing,by the combined use of techniques: NMR,Py-GC-MS,DART-MS,DM, SEM-EDSand-XRD. EXPERIMENTAL Chemicals / Materials Two of the most used colors in Mexico artworks were chosen: the Toluidine Redand the Hansa Yellow (Politec, Mexico), as well as the unpigmented acrylic binderlike Primal® AC33, (Santiago arte conservación y restauración, Mexico).

APS Division of Fluid Dynamics Meeting Abstracts, Nov 1, 2019

Bulletin of the American Physical Society, Nov 19, 2012

techniques through empirical experimentation of modern and industrial materials and tools. Among ... more techniques through empirical experimentation of modern and industrial materials and tools. Among the young artists attending the workshop was Jackson Pollock. They tested different lacquers and a number of experimental techniques. One of the techniques, named by Siqueiros as a "controlled accident," consisted in pouring layers of paint of different colors on top of each other. After a brief time, the paint from the lower layer emerged from bottom to top creating a relatively regular pattern of blobs. This technique led to the creation of explosion-inspired textures and catastrophic images. We conducted an analysis of this process. We experimentally reproduced the patterns "discovered" by Siquieros and analyzed the behavior of the flow. We found that the flow is driven by the well-known Rayleigh Taylor instability: different colors paints have different densities; a heavy layer on top of a light one is an unstable configuration. The blobs and plumes that result from the instability create the aesthetically pleasing patterns. We discuss the importance of fluid mechanics in artistic creation.

MRS Proceedings, 2012

Xavier Guerrero (1896-1974) had an important role in the so-called Mexican Mural Renaissance, as ... more Xavier Guerrero (1896-1974) had an important role in the so-called Mexican Mural Renaissance, as a technical leader in the murals painted by Roberto Montenegro and Diego Rivera in the early 1920's. Jean Charlot, Diego Rivera and David Alfaro Siqueiros considered him as a sophisticated fresco craftsman, whose knowledge came from a popular mural painters guild. In 1941 the Mexican Government donated a School to Chillan, a Chilean town almost destroyed by a strong earthquake. David Alfaro Siqueiros and Xavier Guerrero were commissioned to paint murals on the Mexico School. Between 1941-1942 Guerrero decorated several walls and the staircase ceiling, the mural program is called De México a Chile (From Mexico to Chile). In 2010 another earthquake destroyed part of the ceiling. This study is part of the diagnosis project of De México a Chile, and consists in the characterization of the mortar and painting layers with optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermal analysis (TGA), while textural properties of the mortars were studied with nitrogen adsorption-desorption techniques. Analytical results show a stratigraphic sequence composed of several layers of Portland and lime combinations, and also an interesting painting technique that possibly involves the Portland cement setting process, with the development of specular gypsum.

Molecules, Jan 5, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

PLOS ONE, Oct 30, 2019

Jackson Pollock's most celebrated abstract paintings were produced with the so-called dripping te... more Jackson Pollock's most celebrated abstract paintings were produced with the so-called dripping technique. By pouring liquid paint with the help of a stick or from a can, Pollock deposited viscous fluid filaments on a horizontal canvas, rhythmically moving around it. The intricate webs of lines, ubiquitous in his compositions, have fascinated art historians and scientists. Based on image analysis of historical video recordings, we experimentally reproduced the painting process. We conclude that Pollock avoided the appearance of the hydrodynamic instabilities, contrary to what was argued by previous studies. Pollock selected the physical properties of the paint to prevent filament fragmentation before deposition, and applied it while moving his hand sufficiently fast and at certain heights to avoid fluid filaments from coiling into themselves. An understanding of the physical conditions at which these patterns were created is important to further art research and it can be used as a tool in the authentication of paintings.

Springer eBooks, Oct 29, 2010

arXiv (Cornell University), 2014

This is an entry for the Gallery of Fluid Motion of the 65st Annual Meeting of the APS-DFD (fluid... more This is an entry for the Gallery of Fluid Motion of the 65st Annual Meeting of the APS-DFD (fluid dynamics video). This video shows an analysis of the 'accidental painting' technique developed by D.A. Siqueiros, a famous Mexican muralist. We reproduced the technique that he used: pouring layers of paint of different colors on top of each other. We found that the layers mix, creating aesthetically pleasing patterns, as a result of a Rayleigh-Taylor instability. Due to the pigments used to give paints their color, they can have different densities. When poured on top of each other, if the top layer is denser than the lower one, the viscous gravity current undergoes unstable as it spread radially. We photograph the process and produced slowed-down video to visualize the process.

Conferencia /// Coloquio: 60 Anos de la construccion de CU.Un material perdurable, perpetuo e inm... more Conferencia /// Coloquio: 60 Anos de la construccion de CU.Un material perdurable, perpetuo e inmortal; los problemas de la tecnica en el muralismo a exterior y la integracion plastica. Mtra. Sandra Zetina Ocana. Instituto de Investigaciones Esteticas. UNAM. UNAM. 26 de noviembre de 2012. ///Universidad Nacional Autonoma de Mexico, Facultad de Filosofia y Letras, Posgrado de Historia del Arte, Taller de Integracion Plastica. //// Audio. Duracion: 44 minutos. //// Descarga: Pulse boton derecho del raton sobre el archivo de audio "mp3" que elija y seleccione "Guardar Destino Como...

Arqueología Mexicana, 2015

Intervención, May 1, 2010

Arqueología Mexicana, 2015

Arqueología Mexicana, 2018

Llega ahor aa su quinta decada al debate sobre el Codice Grolier considerado por algunos el cuart... more Llega ahor aa su quinta decada al debate sobre el Codice Grolier considerado por algunos el cuarto codice maya y por otros una mera falsificacion. El proposito de este articulo no es tomar partido por alguna de las posturas, sino mostrar los argumentos materiales que ponen en duda su autenticidad y que no han sido explicados certeramente

Conversaciones con..., 2020

imagen, trad. de Gonzalo María Vélez los cuadros como ventanas y agentes ojos, alas y patas de mo... more imagen, trad. de Gonzalo María Vélez los cuadros como ventanas y agentes ojos, alas y patas de mosca: el martirio de san ponciano de baltasar de echave orio 20 visuales también tienen una historia oculta desde su intencionalidad, que no resulta fácil de desentrañar, tanto como construcciones retóricas, materiales y tecnológicas que aquí se revelarán finalmente mediante la interacción de los compromisos habidos entre el pintor y sus comitentes ignacianos, ambos complacientes con el poder de los recursos miríficos para mostrar, persuadir y conmover a través de la mirada, incrementando los misterios de la fe.