O retrato de D. Frei António de Sousa, Bispo do Porto
: 1758 – 1766 : sistema de tensão de suporte têxtil

  • Alfredo Manuel Ramos Dias (Student)

Student thesis: Master's Thesis


The present work is the result of the study and intervention of conservation and restoration of an oil painting on canvas, dated between the end of the 18th century and the beginning of the 19th century, portraying the Bishop of Porto, D. Frei António de Sousa. Included in a collection of portraits of bishops from the diocese of Porto, it is exhibited in the Gallery of Bishops, in the Paço do Bispo do Porto, presently at the chapel antechamber. The painting presented pathologies essentially associated with constant fluctuations in relative humidity (HR) of the air, such as blooming varnish, cracking and structural deformations. The latter were defined by uneven tensions throughout the painting, stretcher marks and an inadequate setting system. During the process of varnish removal it was possible to identify elements and colours of the composition until then, imperceptible or misinterpreted and with the construction of a humidity chamber it was possible to flatten the painting structure, with the support of a temporary working stretcher. Challenged by the difficulty of controlling environmental conditions, which cause conservation problems common to all the paintings found in this building and in many others in similar institutions due to the architectural characteristics and/or budget constraints, we developed a textile support tension system that could minimize the negative effects on the canvas. Conceived to be accessible to all, at low cost and able to be used in any conservation and restoration workshop; capable of responding to the needs of tension changes, due to the action of humidity and with constant presentation of the real value of the forces exerted in the painting, in N (newtons). The final prototype was the result of several tests of different models, which allowed to evaluate and improve the system that allows tensioning a canvas without static attachment points, at low tension values and guaranteeing constant tension. Despite the disinterested contribution, to all those who want to use this construction solution in a workshop, a technical design was developed for mass production of a final model, hoping to obtain funding for patent registration, matrix production and commercialization of this product. This production can be carried out using metallurgical extrusion or, in a new approach that we intend to continue to develop, through 3D printing. Thus, the aim is to provide the market with a solution capable of responding to most works of art and without the need for the conservator-restorer to be limited to personalized orders and production times.
Date of Award18 Mar 2021
Original languagePortuguese
Awarding Institution
  • Universidade Católica Portuguesa
SupervisorMaria Aguiar (Supervisor) & Arlindo Silva (Co-Supervisor)


  • D. Frei António de Sousa
  • Easel paintings
  • Textile support
  • Relative humidity
  • Stretcher
  • 3D printing


  • Mestrado em Conservação e Restauro de Bens Culturais

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