General Instruction of the Roman Missal: Chapter VI, The Requisites for the Celebration of Mass
I. The Bread and Wine for Celebrating the Eucharist
319Following the example of Christ, the Church has always used bread and wine with water to celebrate the Lord’s Supper.
320The bread for celebrating the Eucharist must be made only from wheat, must be recently baked, and, according to the ancient tradition of the Latin Church, must be unleavened.
321The meaning of the sign demands that the material for the Eucharistic celebration truly have the appearance of food. It is therefore expedient that the Eucharistic bread, even though unleavened and baked in the traditional shape, be made in such a way that the priest at Mass with a congregation is able in practice to break it into parts for distribution to at least some of the faithful. Small hosts are, however, in no way ruled out when the number of those receiving Holy Communion or other pastoral needs require it. The action of the fraction or breaking of bread, which gave its name to the Eucharist in apostolic times, will bring out more clearly the force and importance of the sign of unity of all in the one bread, and of the sign of charity by the fact that the one bread is distributed among the brothers and sisters.
322The wine for the Eucharistic celebration must be from the fruit of the grapevine (cf. Lk 22:18), natural, and unadulterated, that is, without admixture of extraneous substances.
323Diligent care should be taken to ensure that the bread and wine intended for the Eucharist are kept in a perfect state of conservation: that is, that the wine does not turn to vinegar nor the bread spoil or become too hard to be broken easily.
324If the priest notices after the consecration or as he receives Communion that not wine but only water was poured into the chalice, he pours the water into some container, then pours wine with water into the chalice and consecrates it. He says only the part of the institution narrative related to the consecration of the chalice, without being obliged to consecrate the bread again.
II. Sacred Furnishings in General
325As in the case of the building of churches, so also regarding all sacred furnishings the Church admits the artistic style of each region and accepts those adaptations that are in keeping with the culture and traditions of each people, provided that all fit the purpose for which the sacred furnishings are intended.[135]
In this matter as well, a noble simplicity should be ensured such as is the best companion of genuine art.
326In the choice of materials for sacred furnishings, besides those which are traditional, others are acceptable if by contemporary standards they are considered to be noble, are durable, and are well suited for sacred use. In the dioceses of the United States of America these materials may include wood, stone, or metal which are solid and appropriate to the purpose for which they are employed.
III. Sacred Vessels
327Among the requisites for the celebration of Mass, the sacred vessels are held in special honor, especially the chalice and paten, in which the bread and wine are offered and consecrated, and from which they are consumed.
328Sacred vessels are to be made from precious metal. If they are made from metal that rusts or from a metal less precious than gold, then ordinarily they should be gilded on the inside.
329In the dioceses of the United States of America, sacred vessels may also be made from other solid materials that, according to the common estimation in each region, are precious, for example, ebony or other hard woods, provided that such materials are suited to sacred use and do not easily break or deteriorate. This applies to all vessels which hold the hosts, such as the paten, the ciborium, the pyx, the monstrance, and other things of this kind.
330As regards chalices and other vessels that are intended to serve as receptacles for the Blood of the Lord, they are to have bowls of nonabsorbent material. The base, on the other hand, may be made of other solid and worthy materials.
331For the consecration of hosts, a large paten may appropriately be used; on it is placed the bread for the priest and the deacon as well as for the other ministers and for the faithful.
332As to the form of the sacred vessels, the artist may fashion them in a manner that is more in keeping with the customs of each region, provided each vessel is suited to the intended liturgical use and is clearly distinguishable from those intended for everyday use.
333For the blessing of sacred vessels, the rites prescribed in the liturgical books are to be followed.[136]
334The practice is to be kept of building a sacrarium in the sacristy, into which is poured the water from the purification of sacred vessels and linens (cf. no. 280).