Studies on polymeric conservation treatments of ceramic tiles with Paraloid B‐72 and two alkoxysilanes

Abstract

The aim of this study was to evaluate the effect of different polymeric protections applied on ceramic tiles on their mechanical and water absorption properties. Three conservation products were used: the acrylic polymer Paraloid B-72 and two alkoxysilane-based formulations (tetraethoxysilane (TEOS) and IN2210, a polidimetilsiloxane-based formulation). The coatings were applied onto handmade tiles manufactured according to a 18th century procedure. Different application procedures (immersion, brushing, and spraying) were tested. The protection effectiveness was assessed through capillary water absorption and four point bending tests. The mineralogical characterization of tiles was undertaken by XRD. The best protective properties of the tiles were achieved by immersion treatments with Paraloid B-72 based on the protocols followed by the museums restoration departments. Nevertheless, the results of the present work show that the second immersion in Paraloid B-72 solution, commonly made, can be eliminated, as it does not provide any significant increase in the hydrophobic or mechanical properties of the tiles. As a result, there are obvious economical benefits, as the coating process became less time-consuming and more environmental friendly, as the amount of organic compounds is reduced. On the other hand, the use of small volumes of Paraloid B-72 solution applied by brush, or IN2210 sprayed can provide good results, if the only purpose of the treatment is the increase of the hydrophobic properties.

Neutron tomography for the assessment of consolidant impregnation efficiency in Portuguese glazed tiles (16th and 18th centuries)

“…Acrylic polymers and co-polymers are used as protective coatings due to their nonwettability, chemical inertness and environmental stability (Carreti and Dei, 2004). These properties have lead to the extensive use of these polymeric materials as consolidants and/or protectors for the conservation of artworks made of stone, ceramics, glazed tiles, wood and other porous material (Farinha Antunes, 1992;Ribeiro Carrott et al, 1997;Carvalho et al, 2006;Vaz et al, 2008;Constâncio et al, 2010).…”

Consolidation treatments applied to ceramic tiles: are they homogeneous?

“…Destructive testing methods, such as compressive or bending strength tests, are usually used for this purpose (1,2).…”

Penetração e distribuição do consolidante Paraloid® B-72 em cerâmica branca estudada por tomografia com nêutrons

“…Estas substâncias são polímeros acrílicos, comercialmente conhecidos como Paraloid® B-72, B-67 e B-66, Elvacite, Acrilem e, dentre estes, o primeiro é um dos mais empregados. 6 Estes consolidantes atuam no objeto cerâ-mico formando uma película protetora em sua superfície e penetram pelos seus poros, sem no entanto selá-los completamente, deixando sua estrutura estável e permeável à umidade. [7][8][9] Assim, a penetração e sua distribuição no objeto de interesse são fatores chave neste tipo de procedimento.…”

“…Estas imagens referem-se ao vaso que foi mantido na umidade de 35% e permitiram uma visualização macroscópica da distribuição do Paraloid® B-72 em suas paredes, e da profundidade de penetração. 6 A Figura 7a mostra a imagem do vaso íntegro; a Figura 7b evidencia partes internas do material cerâmico, da qual foram removidas com as ferramentas de processamento do próprio software o topo e o lado frontal, de forma a permitir a visualização da profundidade de penetração do Paraloid® B-72 (detalhe em vermelho), bem como a fronteira cerâmica/Paraloid; as Figuras 7c e 7d expõem partes do corpo cerâmico e do consolidante no interior da cerâmica, o que permitiu a visualização de duas falhas (indicadas por setas) com tamanho considerável, do processo de impregnação do consolidante.…”