JAIC 2004, Volume 43, Number 1, Article 2 (pp. 03 to 21)
JAIC online
Journal of the American Institute for Conservation
JAIC 2004, Volume 43, Number 1, Article 2 (pp. 03 to 21)

POLYMER TREATMENTS FOR STONE CONSERVATION: METHODS FOR EVALUATING PENETRATION DEPTH

FRANCESCA CASADIO, & LUCIA TONIOLO



2 MATERIALS


2.1 STONE SPECIMENS

The project focused on lithotypes of varying porosity, widely occurring in historic architecture and monuments in Italy. In particular, results are reported regarding substrates listed below:

  • Noto stone, a highly porous calcareous stone with total open porosity ranging from 25% to 35%, widely present in the historic architecture of the famous baroque town of Noto, near Syracuse, Sicily.
  • Yellow Angera stone, a Triassic dolomitic sedimentary rock containing trace amounts of clay and iron hydroxide (responsible for the yellow color), characterized by 11.5% total open porosity, widely present in structures in Lombardy.
  • Candoglia marble, a metamorphic, compact calcareous stone characterized on average by 1% total open porosity, largely employed in building and sculpture: it is the construction material of the Cathedral of Milan (14th‐19th century).


2.2 POLYMER TREATMENTS

The resins used for treatment of the stone specimens were:

  • Paraloid B-72 (Rohm & Haas), ethylmethacrylate/methylacrylate copolymer
  • TFEMA/MA, a partially fluorinated, experimental, 2,2,2 trifluoroethylmethacrylate/methylacry-late copolymer (Ciardelli et al. 2000), basically a fluorinated homologue of Paraloid B-72;
  • Wacker 290 (Wacker Chemie), a water repellent based on oligomeric alkylalkoxysiloxanes.

Details concerning these polymers' characteristics (including molecular weights and glass transition temperatures [Tg]), efficacy, and UV resistance are reported elsewhere (De Witte et al. 1993; Melo et al. 1999; Chiantore and Lazzari 2000; Alessandrini et al. 2000a, 2000b).


Copyright 2004 American Institution for Conservation of Historic & Artistic Works