Conservation: A Closer Look

 

A Spanish Colonial Anquera

ATDetail

Fig. 1. Horse anquera (detail). Gift of the Heirs of David Kimball, 1899.  Image © President and Fellows of Harvard College, Peabody Museum of Archaeology and Ethnology, 99-12-20/52901. Measurements: 100 x 107 x 6 cm (39 3/8 x 42 1/8 x 2 3/8 in.)

What is it made of?

Conservators often examine objects under magnification and carry out material analysis to take a closer look at an object’s materials and technology.

This leather Anquera (horse trapping) from Mexico is beautifully embroidered with different fibers. Knowing the fiber type would assist in better understanding the object and help define the conservation treatment. Analytical techniques were used to identify silk, silver-wrapped threads, and  plant fiber (perhaps Agave) cords in the intricate designs on the leather panel and flaps.

Close-up examination

Details of the horse anquera’s construction was examined using a M80 Leica stereomicroscope:

silverwrap

Fig. 2. Silver-wrapped cords under magnification

wrapped

Fig. 3. Plant-fiber embroidery cord (left) with silver-wrapped cords under magnification

Fibertext

Fig. 4. Silver wrapped threads, blue/green silk using long, short satin stitch, leaf fiber (Agave) using stem stitch

trim

Fig. 5. Metallic Trim - Measuring 7.5-8 mm wide.

This trim was hand woven on a rigid loom that held the metal threads relatively taut. The trim is warp-faced plain weave and is appliqued to leather by stitching down on each of its loom-finished edges with a pair of 2 ply S (pale yellow/ivory) silk cords. The warp and weft threads are made from a silver- alloy foil wrapped (S direction) on a silk core.t  

X-Ray Fluorescence (XRF)

xrf

Fig. 6. Portable handheld analyzer applied to the silver-embroidered details.

To help identify materials X-Ray Fluorescence (XRF) analysis was carried out on the silver trim, silver wrapped cords, and likewise on the iron jingels (ruido).

XRF is used for elemental analysis to identify elements present in primarily inorganic materials such as metals, ceramics, and glass. XRF is utilizes X-ray emission and does not cause damage to the object. To examine the metallic threads of the anquera, a portable Bruker S1 Tracer III-IV Handheld XRF analyzer was used.

An example of the XRF results on the silver wrapped threads is shown below.

point

Fig. 7. Location of XRF analysis of silver-wrapped silk cords

XRF chart of silver wrapped threads

Fig. 8. XRF spectra showing silver peaks on silver wrapped cords

Polarized light microscopy

To identify types of fibers used to construct the anquera polarized light microscopy was undertaken on selected fibers. Only tiny fiber samples are needed for this analysis. Light microscopy is used for identification and analysis of fibers and pigments. Characteristics of fibers can be viewed on a compound light microscope using a variety of techniques to compare with known samples for identification. For this analysis we used a digital Leica microscope attached to a laptop.

Leica digital microscope and laptop

Fig. 9. Leica digital microscope (DM750) set-up with laptop

Silk under microscope.Anquera

Fig. 10. Blue/green silk embroidery threads under polarized light microscopy (PLM).

 

PLM1

Fig. 11. Wool fibers on verso under Leica microscope