Tumacácori-Methodology

In January 2015, the Architectural Conservation Laboratory conducted a site visit in order to conduct preliminary investigations to aid in subsequent analyses and assessment. During this trip, high-resolution photographs of the façade were taken in order to create an ortho-rectified photomontage as a base image for future inspection. This was done by using a DSLR camera to photograph portions of the façade’s surface to then digitally stitch the images to fit previous photogrammetric measurements as recorded during the Historic American Buildings Survey conducted in 1975 by Perry, Myra, and Christina Borchers at Ohio State University.

In addition to preliminary documentation, original surface finishes and subsequent repair campaigns were analyzed in-situ and samples were taken for further laboratory analysis. Historic images informed sampling strategy and all sample locations were carefully photographed and notated. Samples of finish coatings were also taken from previously fallen fragments that had been collected by NPS staff.

The completed rectified montage.

Using high-resolution photography to create an ortho-rectified photomontage.

Taking small samples of repair campaigns for further analysis

Working from the historic watercolor rendering helps inform decisions about where to sample.

Plaster survey form to verify conditions of the interior plaster was used in the field.

Based on the condition assessment of interior plaster at the mission church produced in 2014 by the Drachman Institute at University of Arizona, the ACL conducted a condition verification survey during the project. Our goal was to confirm previously identified conditions and determine those condition to be treated.

To aid the field verification process, a survey form was created and used in the field. As treatment methodology should be programmed differently according to materials and conditions, presence of finishes, presence of historic edging or fill repair and their characteristics were considered imporatant.

As a result, cleaned condition drawings focusing on plaster conditions and a corresponding condition glossary were produced.