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A Comparative Study of Ethyl-silicate–based Consolidants on Earthen Finishes

2011; Routledge; Volume: 50; Issue: 1 Linguagem: Espanhol

10.1179/019713611804488964

1945-2330

Amila Ferron, Frank G. Matero,

Conservation Techniques and Studies

AbstractAbstractComparative evaluation was performed on three commercially available ethyl silicates as possible consolidants for earthen finishes: uncatalyzed Silbond 40 in a 1:1 solution with ethanol, Conservare OH100, and Funcosil SAE 300E. Of particular interest was the compatibility of ethyl-silicate–based consolidation with water-based reattachment treatments. The testing program utilized facsimile coupons representing earthen finishes found at Mesa Verde National Park in Colorado and measured exposure to changing relative humidity, response to liquid water, surface cohesion, and effect on appearance. Samples were subjected to measurement with a linear variable differential transformer, environmental scanning electron microscopy, timelapse photomicrography, observation during wet-dry cycling, water drop absorption testing, colorimetry, and photographic recording. A comparison of the three ethyl-silicate–based consolidants clearly demonstrated that they can perform very differently on the same earthen substrate, and that careful selection should be made prior to use. Many questions remain regarding the influence of the finish composition, finish condition, and environmental conditions on the effectiveness of consolidation; further test development and testing are recommended.TÍTULO—Estudo comparativo de consolidantes à base de silicato de etila em revestimentos de terraRESUMO—Foi realizado estudo comparativo entre três silicatos de etila disponíveis no mercado, como possíveis consolidantes para revestimentos em terra: Silbond 40 não catalítico em solução de 1:1 com etanol, Conservare OH100 e Funcosil SAE 300E. Especialmente interessante foi a compatibilidade da consolidação à base de silicato de etila com os tratamentos de rejunte em base aquosa. O programa de teste utilizou cópias de certificados exemplificando revestimentos de terra encontrados no Mesa Verde National Park (Parque Nacional Mesa Verde) no Colorado e mediu a exposição frente à variação da umidade relativa, reação à água no seu estado líquido, coesão da superfície e efeitos no aspecto. As amostras foram submetidas a sensores para medição de deslocamento linear, microscópio eletrônico de varredura ambiental, fotomicrografia time-lapse, observação do ciclo molhado-seco, teste de absorção de água, colorimetria e registro fotográfico. Uma comparação entre os três consolidantes à base de silicato de etila demonstrou claramente que eles podem atuar de maneira muito diferente no mesmo substrato de terra e que uma seleção cuidadosa deveria ser feita antes de usá-los. Ainda restam muitas questões a respeito da influência dos componentes, do estado de conservação e das condições ambientais dos revestimentos sobre a qualidade da consolidação; são recomendados o desenvolvimento e a realização de testes adicionais.Comparative evaluation was performed on three commercially available ethyl silicates as possible consolidants for earthen finishes: uncatalyzed Silbond 40 in a 1:1 solution with ethanol, Conservare OH100, and Funcosil SAE 300E. Of particular interest was the compatibility of ethyl-silicate–based consolidation with water-based reattachment treatments. The testing program utilized facsimile coupons representing earthen finishes found at Mesa Verde National Park in Colorado and measured exposure to changing relative humidity, response to liquid water, surface cohesion, and effect on appearance. Samples were subjected to measurement with a linear variable differential transformer, environmental scanning electron microscopy, timelapse photomicrography, observation during wet-dry cycling, water drop absorption testing, colorimetry, and photographic recording. A comparison of the three ethyl-silicate–based consolidants clearly demonstrated that they can perform very differently on the same earthen substrate, and that careful selection should be made prior to use. Many questions remain regarding the influence of the finish composition, finish condition, and environmental conditions on the effectiveness of consolidation; further test development and testing are recommended.TITRE—Une étude comparative des consolidants à base de silicate d'éthyle pour les revêtements en terreRÉSUMÉ—Une évaluation comparative a été effectuée sur trois silicates d'éthyle disponibles comme consolidant pour les revêtements en terre: le Silbond 40 non-catalysé dans une solution 1:1 avec de l'éthanol; le Conservare OH100; et le Funcosil SAE 300E. Une caractéristique intéressante des consolidants à base de silicate d'éthyle réside dans leur compatibilité avec les traitements adhésifs à base d'eau. Le programme de tests a été effectué à l'aide d'échantillons fac-similés représentatifs des revêtements en terre du Mesa Verde National Park (parc national du Mesa Verde) au Colorado, pour évaluer les changements face aux fluctuations d'humidité relative, la réponse à l'eau liquide, la cohésion de la surface et l'effet sur l'apparence. Les échantillons ont été évalués à l'aide d'un transformateur différentiel à variation linéaire, un microscope électronique à balayage environnemental, de la microphotographie vue par vue, des observations lors de cycles d'assèchement et de mouillage, des tests d'absorption de gouttes d'eau, des tests de colorimétrie, ainsi que d'une documentation photographique. Une comparaison entre les trois consolidants à base de silicate d'éthyle démontre clairement qu'ils agissent de façon très différente sur les substrats en terre et qu'une sélection méticuleuse doit être effectuée avant de les utiliser. Plusieurs questions demeurent concernant l'influence de la composition du fini et de son état, ainsi que des conditions environnementales sur l'efficacité de la consolidation; des tests supplémentaires sont donc recommandés.TITULO—Estudio comparativo de consolidantes basados en silicato de etilo sobre acabados de barroRESUMEN—Se realizó una evaluación comparativa de tres silicatos de etilo que se consiguen comercialmente como posibles consolidantes para acabados de barro: Silbond 40 sin catalizar en solución 1:1 en etanol, Conservare OH100, y Funcosil SAE 300E. La compatibilidad de los consolidantes basados en silicato de etilo con tratamientos acuosos de reacoplamiento fue de particular interés. El programa de pruebas utilizó cupones facsímiles que representaban acabados de barro encontrados en el Mesa Verde National Park (Parque Nacional Mesa Verde), en Colorado, y se midieron los cambios frente a variaciones en la humedad relativa, la respuesta frente al agua líquida, la cohesión superficial y los efectos sobre el aspecto. Las muestras se sometieron a mediciones con un transformador para variaciones lineales diferenciales y con un microscopio electrónico de barrido ambiental, además de fotomicrografía secuencial, observación durante el ciclado húmedo/ seco, pruebas de absorción de humedad por gota de agua, y registro fotográfico. Una comparación de los tres consolidantes basados en silicato de etilo demostró claramente que se pueden comportar de manera muy diferente sobre el mismo substrato de barro, y que debe realizarse una selección cuidadosa antes de su uso. Quedan muchas preguntas relacionadas a la influencia de la composición del acabado, la condición del acabado, y las condiciones medioambientales sobre la efectividad de la consolidación. Se recomiendan el desarrollo y la realización de más pruebas.