Our Lady of Guadalupe - Technical Analyses

Technical Analyses

Neither the fabric ("the support") nor the image (together, "the tilma") has ever been analyzed using the full range of scientific resources available to museum conservationists. Nevertheless, four technical studies were conducted between 1751–2 and 1982. Of these, the findings of three have been published. All were commissioned by the authorized custodians of the tilma in the Basilica, and in every case the investigators had direct and unobstructed access to it.

Studies conducted between 1751–2 and 1982

MC – in 1756 a prominent artist, Miguel Cabrera, published a report entitled "Maravilla Americana" containing the findings made by himself and six other painters in 1751 and 1752 from ocular and manual inspection.

G – José Antonio Flores Gómez, an art restorer, discussed in a 2002 interview with the Mexican journal Proceso (magazine) certain technical issues relative to the tilma, on which he had worked in 1947 and 1973.

PC – in 1979 Philip Callahan, biophysicist and USDA entomologist, specializing in Infrared imaging, took numerous infrared photographs of the front of the tilma. His findings, with photographs, were published in 1981.

R – "Proceso" also published in 2002 an interview with José Sol Rosales, formerly director of the Center for the Conservation and Listing of Heritage Artifacts (Patrimonio Artístico Mueble) of the National Institute of Fine Arts (INBA) in México City. This interview was interspersed with extracts from a report R had written in 1982 of the findings he had made during his inspection of the tilma that year using raking and UV light, and – at low magnification – a stereo microscope of the type used for surgery.

Summary conclusions ("contra" indicates a contrary finding)

(1) Support: The material of the support is soft to the touch (almost silken: MC; something like cotton: G) but to the eye it suggested a coarse weave of palm threads called "pita" or the rough fiber called "cotense" (MC), or a hemp and linen mixture (R); the traditional understanding is that it is ixtle, an agave fiber.

(2) Ground, or Primer: R asserted (MC and PC contra) by ocular examination that the tilma was primed, though with primer "applied irregularly." R does not clarify whether his observed "irregular" application entails that majorly the entire tilma was primed, or just certain areas – such as those areas of the tilma extrinsic to the image – where PC agrees had later additions. MC, alternatively, observed that the image had soaked through to the reverse of the tilma.

(3) Under-drawing: PC asserted there was no under-drawing.

(4) Brush-work: R suggested (PC contra) there was some visible brushwork on the original image, but at best in only one minute area of the image ("her eyes, including the irises, have outlines, apparently applied by a brush").

(5) Condition of the surface layer: The three most recent inspections agree (i) that significant additions have been made to the image, some of which were subsequently removed, and (ii) that the original image has been abraded and re-touched in places. Some flaking is visible (mostly along the line of the vertical seam, or at passages considered to be later additions).

(6) Varnish: The tilma has never been varnished.

(7) Binding Medium: R provisionally identified the pigments and binding medium (distemper) as consistent with 16th c. methods of painting sargas (MC, PC contra for different reasons), but the color values and luminosity are exceptional.

The technique of painting on fabric with water-soluble pigments (with or without primer or ground) is well-attested, although such a survival from the 16th c. is unprecedented. The binding medium is generally animal glue or gum arabic (see: Distemper). Such an artifact is variously discussed in the literature as a tüchlein or sarga. The tilma, considered as a type of sarga, is by no means unique, but its state of preservation is remarkable.