Following the corrosion process of gray castings of the XlXth century in two fountains at Guanajuato, Mexico

摘要

This paper describe the corrosion phenomena around a pair of fountains of gray cast iron, located in the Mexican state of Guanajuato, with a probable French factory from the second half of the XlXth century. Both are restored in the last five years because they have a serious corrosion problems related with the salt content and turbulence of the water. The constant dropping of water in some surfaces destroy two coatings usually used in conservation of metals, acrilic and epoxi colorless varnishes. The ideal solution is change the current tap-water, and use a permanent control of the salt content of the water. But the local authority refuse to implement a water control system. For that reason the final protection of both monuments was made with a epoxi coating with coaltar in order to resist the salt content of the water, over a primer of epoxi enriched with organic zinc. Five years after, we want to follow the evolution of the treatment and the performance of the coating against the constant movement of the water and the periodic cycles of wetting and dry. For that, we record the actual condition of the fountains, and check the results by recreation of the corrosion process with samples and measuring the corrosion dynamic by electrochemical probes. This research it's a first step in the knowledge of rich cast iron heritage in public furniture and monuments in Mexico and it conservation requirements.