Truth and vanity
: the retouching techniques on dry plate negatives of Portuguese collections of the first half of the twentieth century

Student thesis: Doctoral Thesis


This thesis aims to understand better the retouchings on dry plate negatives and contribute to their preservation, updating established conservation practices. Archives of old photography studios, and photographers, are kept for their recognized historical and cultural value. These are mostly negative collections, which are frequently retouched. The research focused on several Portuguese negative collections from the first half of the twentieth century. It was divided into a three-way approach: 1, establish a historical framework to explain the retouching practices, their acceptance, criticisms, and how they relate with contemporary aesthetics, social-cultural dimensions and contribute to a better knowledge of the visual culture of the time; 2, review the practice of retouching to identify motivations, identification of materials and techniques and understand intended effects; 3, revise the established conservation procedures. Frequently not valued in the past, retouched photography exists since the birth of photography itself. Furthermore, although often criticized, retouching photography is an accepted part of the photographic process. However, it is not only relevant to explain and characterize a photographer's technique. While a hidden practice, retouching has a significant impact on the visual culture of its time and even how images and aesthetics of that time help evolve and influence photography today. Many authors identified the aproximation to the truth and the photographer's eye as the primary motivation. When photography was still debating its role in the arts, retouching was central to the discussion and used by each side as an argument both in favor and against. However, for the professional photographer, retouching negatives was necessary to please the client, assure flawless prints, and even a measure of pride in their work's quality. Fourier-transform infrared spectroscopy (FT-IR) was used to complement the identification of retouching materials. The result is a compilation of spectra that can be used as references in future studies. Some flaws in current conservation procedures have been identified, with consequences in the value and preservation of retouched negative collections. Conservation of archive collections can no longer be dissociated from digital dissemination. The conservator needs to take a more active role in advocating for collections' materiality in digital environments to ensure their preservation and truthful representation of the photographic cultural heritage. The retouching practices were kept forgotten for a long time. This work now shines a light on the importance of preserving retouched collections and open directions for future research in the fields of Conservation, Art History, and other Social Sciences.
Date of Award28 Feb 2022
Original languageEnglish
Awarding Institution
  • Universidade Católica Portuguesa
SupervisorLaura Castro (Supervisor), Carolina Barata (Co-Supervisor) & Margarita San Andrés (Co-Supervisor)


  • Photography
  • Dry plate negative
  • Retouching
  • Portrait conservation
  • Portuguese collections


  • Doutoramento em Conservação e Restauro de Bens Culturais

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