Dr Lynch is an authority on historic building limes and lime-based mortars for brickwork: as well as early Portland cement binders. It was his pioneering work in such papers as ‘Lime Mortars for Brickwork: Traditional Practice, Modern Misconceptions’ (1997) among others, that shifted a lime revival that had become entrenched in believing and promoting all historic mortars based on pure, ‘air lime’ binders, always slaked to matured putty and mixed with ‘well-graded’ aggregate.
This paper and his countless lectures and demonstrations highlighted the use of various types and classes of building limes used on historic brickwork, of how most mortars for bricklaying were based on quicklime slaked within a volume-based measure of whatever aggregate was local and readily available, as ‘hot lime’ mixed mortar. Dr Lynch was simultaneously, over 20 years ago, the first authority to say that the modern method of applying matured slaked lime washes cold was not the traditional method and that his father and grandfathers – on both sides of his Irish family – always applied it hot straight from slaking.
He was also the first to realise how modern interpreters of records of traditional mortar mixes discussed within historic craft books – artisans, architects, engineers, historians – were misinterpreting the mix ratios given, such as the 1: 3, as being based on slaked, or hydrated, (to lime putty or a dry-hydrate) and had for years been using them secure in that
belief. He was able to elucidate in ‘The Myth in The Mix’ (eventually published in 1999) as well as to practically demonstrate that this was wrong and that first the ratios were based on quicklime. Furthermore, that due to the expansion of quicklime during slaking within the aggregate all resulting hot-lime mixed mortars were to be found as lime-rich as historic mixes, and sharing with them the range of lime particles visually evident, rather than the lean, binder-deficient, modern mortars devoid of the lime inclusions that he had constantly been seeing and troubling him on his travels to heritage projects.
Dr Lynch is a highly-respected committee member of the Building Limes Forum (BLF)