Archive note: I conducted this interview for the National Center for Preservation Technology and Training’s Preservation Technology Podcast. It was originally published by NCPTT/National Park Service on September 5, 2011. I’m preserving a record of the conversation here as part of my podcast and interview archive. The original NCPTT/NPS source remains the authoritative publication.
From the transcript
This conversation makes clear that “preservation technology” was never limited to digital tools. I ask whether ordinary people can learn these methods and, near the end, explicitly ask about DeGruchy’s responsibility to pass the knowledge along. The technology here is material knowledge: accumulated craft practice, terminology, judgment, and technique that can disappear if it is not transmitted.
In this conversation
- Historic lime mortar and its continuing role in masonry conservation and building preservation
- Differences among lime putty, hydraulic lime, Portland cement, and traditional mortar systems
- Why compatibility matters when repointing historic brick and stone masonry
- How inappropriate modern mortar can damage older masonry assemblies
- Traditional building technology, craft practice, and the diagnostic judgment required for successful repairs
- What homeowners, contractors, preservationists, and masons need to understand before undertaking repointing work
- The importance of hands-on training and experienced practitioners in maintaining traditional building knowledge
- Knowledge transmission: how specialized craft expertise survives when one generation of practitioners teaches the next
Andy DeGruchy explains the history and continuing importance of lime mortar, the differences among lime types, appropriate repointing, and the body of practical knowledge carried by experienced masons and conservators.
Series: Preservation Technology Podcast
Episode: 033
Guest: Andy DeGruchy
Interviewer: Jeff Guin
Original publisher: National Center for Preservation Technology and Training / National Park Service
Theme: Conservation Science & Materials
Listen, read the transcript, and view the original episode at the National Park Service.
Preservation note: A preservation copy of the original MP3 is retained in the Voices of the Past archive.