This later nineteenth-century tabernacle frame of ebony-veneered soft wood was designed to house reverse-painted glass. The technique of reverse painting on glass, often called "verre eglomisé", dates to the Roman era, and was widely practiced in Europe by the early sixteenth century. Essentially, an image is painted on the back of a transparent glass or polished rock crystal support and meant to be viewed through it, the substrate becoming an integral part of the painting. The Lehman glass panels were probably painted in Lombardy in the second half of the sixteenth century.
This tabernacle house altar has a semicircular pediment and rock crystal columns with silver-gilt Corinthian capitals and bases. A cast silver-gilt relief of God the Father in Benediction fills the pediment, which is surmounted by an agate urn with silver-gilt mounts flanked by two pointed agate finials. Cast silver-gilt appliqués decorate the entablature, the columns and the predella. The reverse-painted central arched panel represents the Adoration of the Shepherds while below, a narrow frieze of smaller vertical plaques shows the Adoration of the Magi in the center, flanked by the Angel Gabriel and the Virgin of the Annunciation. The outer panels show the Eucharistic host, chalice, and paten on the left and the "Arma Christi" on the right.
Although its style dates from the early seventeenth century, the wooden framework for this house altar was built in the nineteenth century, probably by Reinhold Vasters (1827-1909) or someone in his workshop. Vasters was a highly skilled German silversmith and goldsmith who for a time served as restorer at the Aachen Cathedral treasury. There, in the spirit of nineteenth-century historicism, he not only restored but also replaced worn or damaged liturgical objects. It is likely that the Lehman tabernacle house altar was made expressly to house a set of sixteenth-century reverse-painted panels. The unified program and the similarity of the style of the painting on the ten rock crystal panels suggest that they were scavenged from a single piece.