Excerpts of 1964 report from curator, Spanish Colonial Department, Museum of New Mexico
These shields were made on mission ranches in northern Mexico which had herds of cattle. They are said to have been made of bull hides, usually three layers, cut and laced when fresh and let dry. I doubt that they were put in a form or mold, The round one, or "rodela" was simply convex. The kidney shaped ones were also convex, curving from the middle backward to the sides, and slightly backwards at the bottom and still less at the top. I believe the thong lacings held them in shape when new. Once set they would stay in shape unless wet. The oil painting on them probably kept water off the hide in the field. What I call "native" varnish was extensively used; a mixture of rosin and wax boiled down in water. I believe this was also laid on after painting the shields.
The missions contracted to supply such shields in return for military protection from hostile tribes. The shields were made by neophyte or mission Indians under the direction of the mission priests. The hide shield in the Metropolitan Museum collections (Grancsay Div.) said to be from Spain is very much in the same way as the colonial specimens. Only the heraldic painting differed, monks and Indians rather improvised on this.
The shields had thong slings to hang them by, either on a peg at rest or from the saddle bow. They also had a smaller loop that slipped over the hand so the shield was worn on the forearm in battle. I think you will find the fragments of these on the backs of your specimens.
Although bull hide will hold its shape within reason, exposure to weather and careless placement when wet, in storage, naturally warped the shields in time.
The shields were definitely intended to be HARD, not flexible, as they were substitutes for the metal shields and adequate against arrows and lances. The arrival of firearms in quantity in the southwest was only with the eastern U.S. men, trappers and trail traders and then the army. Hence the lance, bow and leather shield were in use in New Mexico and California until 1846.
Excerpt from 1960 report on Western material at the Smithsonian
The shields were made of three thicknesses of rawhide laced together with narrow 1/8 inch strips of rawhide. In this particular specimen the lacings outline the Spanish coat of arms painted on the surface of the shield. I might add that only the officers' shields and possibly the high ranking non-officers' shield were painted. The shields of the private soldier were not painted: they were plain leather fastened together in the same manner as described, and in New Mexico at least, were sometimes circular and unpainted.
This form of shield (adarga) came with Cortez into Mexico during the early part of the 16th century. It was a form borrowed from the Moors, who were perhaps some of the best light cavalry in the world at that time, and after whom the Spaniards patterned their arms, horse gear and methods of fighting. The other system of fighting which the Spanish used was that which developed in Europe through the use of heavy plate armor. The Arab style of fighting and riding was known as "jinete." The European style of riding was known as riding "estradiota." Briefly the differences were that a man riding the Moorish style rode with his legs bent from the knee and guided his horse by the pressure of his knees. That was also known as riding with a short stirrup. The "estradiota" style was riding with a long stirrup. In other words , the legs were extended straight down and sometimes outward. This system was brought about by the use of the heavy armor. By the 18th century both styles were well established among the Spanish and the highest compliment that could be rendered by a Spanish nobleman was to say that he rode "en ambas silias," indicating that he was proficient in the Moorish style with Moorish weapons as well as in the European style with European weapons.
In fighting in Moorish style the adarga was used (the word is derived from the Arabic, adargar, which means to cover or protect). The shields during the 16th century were brought in from North Africa. They were made of leather and were roughly heart-shaped, wider at the top than at the bottom. The Spanish at times made them in the same style but with wood covered with light plates of armor or leather.
Excerpt of 1966 conservation report
The shield is circular: it measures approximately 58.3 cm. in diameter. It comprises two layers of "bull hides" fastened together by thin flat thongs stitched in a circular pattern.
Attached to the reverse side are strips of hide used presumably for wearing or for handling the shield. A 10 cm. split in the bottom layer is visible in the second photograph. Several of the thong stitches have broken.
The top layer of hide is painted, thickly and freely, with a paint which is insoluble in water, turpentine and ethanol; and soluble in isopropyl alcohol and acetone. Microscopic examination reveals the presence of a red ground painted over with a dark blue. Other pigments present are yellow, orange and white. The orange is covered by small grey globules; a dark brown glaze conceals the bright yellow. There is a greenish brown glaze over much of the paint, which is possibly the "wax rosin" mentioned by Miss Boyd in her letters of June, 1964, and December, 1965, a "native varnish" applied over the paint to further protect it.
The hides are dry but not brittle. On the upper layer the paint is firmly attached to the hide but the surface of the skin has deep scales: small sections have drawn apart, leaving the surface with a network of cracks. Except for a few losses the paint surface is intact. As apparent from a comparison of the photographs, the surface is covered with a thick layer of dust.