COMPATIBILITYAND EFFICIENCY OF RESTORATIONPRODUCTS

FOR ARTEFACTSIN NEAPOLITANYELLOW TUFF

Emma Angelini*, Sabrina Grassini*, Daniele Fulginiti**, Marco Parvis**, Alessandro Segimiro°

1DipartimentodiScienzaApplicataeTecnologia,PolitecnicodiTorino, CorsoDucadegliAbruzzi24,10129Torino,

Italy, sabrina.grassini@polito.it

2 3

Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino,

Italy, marco.parvis@polito.it N

o

variaRestauris.r.l.,ViaMarcoPolo19,28100Novara,Italy, a.segimiro@gmail.com

ABSTRACT

This paper deals with the safeguard of Neapolitan Yellow Tuff (NYT) artefacts by means of the

application of surface coatings and consolidants commonly used for stones and plasters. Three commercially

available restoration products (Estel1100, NanoEstel, and Kremer K52), based on ethyl silicate and

polysiloxanes, amorphous silica and acrylic microemulsions, have been tested on NYT samples, previously

characterizedbythemineralogicalandmicrostructural pointofview.

The aim on the study was to assess the ability of the restoration products to modify the water absorption

process of the stone, thus guaranteeing a protective action against water infiltration, while allowing the

evaporation of free water present in the tuff. Two series of laboratory tests have been carried out: i) water

absorption with contact sponge, ii) water vapour permeability test in water and in aqueous sulphate solution,

in order to assess, in the second case, the appearance of phenomena of surface crystallization of sulphates.

The microchemical and micromorphological characterization of NYT samples was carried out by means of

SEM-EDSmicroscopy.

From the experimental findings, all the tested restoration products reduce the water absorption of the

treatedNYTspecimensthatcontemporarilymaintain,asrequested,agoodwatervapourpermeability.

In order to assess the consolidating/protective performance of the restoration products for longer periods,

themeasurementcampaignisstillrunning.

Key-words: Stone restoration, Neapolitan Yellow Tuff, Stone consolidants, Water vapour permeability,

Saltsprecipitation