These candles are, of course, sacramentals. Sacramentals are objects that have been blessed and used for sacred purposes by the church. Sacramentals are part of the prayer of the church and can confer grace through the power of that prayer, which connects us to the paschal mystery of Christ. Also, sacramentals often remind us of one or more of the seven sacraments which were instituted by Christ to strengthen us and give us grace.
But when a sacramental is old or partially used up — like an old candle — it cannot just be tossed out like other old things. Canon law states that sacred objects are to “be treated with reverence” and not “made over to secular or inappropriate use” (can. 1171).
By custom, when a sacramental is destroyed — technically returned to its basic elements, such as earth, water or air — and is no longer recognizable, it can be disposed of as you would any other groups of basic elements. So an old blessed candle may be burned, which destroys it.
For paschal candles, many religious goods sellers — such as where the candle first came from — will recycle old paschal candles. Some of these dealers will use the recycled wax to make initiation candles used at baptisms.
Another traditional way of disposing of old paschal candles is no longer used, but has a church history of more than 1,000 years.
In Rome, dating back to at least the ninth century and possibly even 400 years before that, old paschal candles were made into wax disks called Agnus Dei. The wax disks were stamped with the figure of a lamb. (Agnus Dei means “Lamb of God” in Latin.) The lamb — a revered symbol for Christ — usually carried a cross or flag. The back of the wax disk bore various images — such as saints or the name of the reigning pope.
The Agnus Dei disks were made on Holy Saturday from the old paschal candle. The candle was melted down and its wax was mixed with chrism and scented oils such as balsam. The disks were then blessed by the pope. Later, Agnus Dei disks were dipped into chrism and other oil as they were blessed by the pope.
The papal blessing took place on the Wednesday of Easter Week and the sacramental disks distributed the following Saturday. (That Saturday is sometimes called White Saturday.) Most often, the Agnus Deis were worn around the neck in the hopes of receiving strength and protection.
These Agnus Dei wax disks were distributed by the pope as he saw fit. Often they were given to visiting cardinals — placed inside the cardinal’s inverted miter by the pope – and the cardinals then distributed them as they chose.
Because they were blessed, the Agnus Dei disks were sacramentals. And they were rare. Traditionally, the pope would bless these wax disks in the first year of his reign, and then not again until seven years had passed. He would bless new Agnus Dei sacramentals at Easter once every seven years after that.
It seems that the last pope to bless Agnus Dei sacramentals was Pope Paul VI during the 1964 Easter season, the first of his reign. It does not seem that he did so again. After that, the blessing immediately fell out of practice. There are no reports of any subsequent pope reviving it.
Sources: Catholic Encyclopedia; the Diocese of San Jose, Calif.; sacramentals.org; fisheaters.com; the diocesan Worship and Evangelization department.