Summary

Following an analysis of the various classifications of pores, the discussion hinged on the focal point: 'as soon as we become involved in Cultural Heritage what exactly are we looking for when we speak of porosity. In other words what are our requirements from the practical point of view? What type of porosity affects the phenomena we are interested in?'

The three topics that led the discussion were:

• the macropore/micropore dilemma;
• the form of pores and their three-dimensional representation;
• the necessity for standards of reference.

Pore space, continuity and connectivity were examined closely. Possible instrumental methodologies such as nitrogen adsorption, tomography and neutron radiography were proposed to replace or complement mercury porosimetry.

Proposals aimed at providing instruments for studying porosity in three-dimensional terms led to interesting suggestions with regard to the use of solutions capable of depositing a precipitate on the walls of the pores (for example, silver chloride) and to the commitment of some participants to pursue this line of study.

Other proposals underlined the absence of models of correlation between porosity, the nature of pores and water absorption, permeability, capillarity, etc. The possibility of pursuing further studies in this field was taken into consideration.

The discussion then focused on the lack of materials as standards of reference, the problem of reproducing inter-laboratory measurements, and the necessity of drafting a standard methodology for measuring and expressing porosity data (an update of the Italian Normal 4/88 recommendation would be welcomed by many of those present).

The discussion concluded with a proposal to create working groups on these specific aspects, with the aim of making a critical and detailed appraisal of the state of knowledge so far acquired.

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updated on: 22 February, 2007