ABSTRACT: On-site surveys and tests, especially non-destructive or minimally invasive, are recommended for a correct diagnosis of historic masonry structures. In the most recent Italian construction technical law, an approximate estimation of mortar joints strength is suggested instead of its direct determination on-site, which could present several problems. First, almost no testing standards are proposed and only few techniques are available. Even commercially available equipment for the indirect evaluation of mortar strength is scarce and generally not sufficiently sensitive to test historic, weak mortars, although some penetrometric tools are now suitable for such purposes. Sampling mortar on-site for laboratory testing is quite difficult although possible. This paper presents a laboratory experience of sampling and double punch testing on hydraulic lime mortar joints extracted from new and artificially aged brick masonry specimens in order to evaluate the feasibility of the method and also to demonstrate if the ageing procedure was effective.