Why some parishes use unbleached candles during Lent

While not a requirement, some parishes use unbleached candles to highlight the penitential character of Lent.

Prior to the Second Vatican Council, unbleached candles were a more common sight in parishes, though typically reserved to Requiem Masses and Good Friday. However, some liturgists of the late 19th and early 20th centuries even recommended unbleached candles to be used during Advent and Lent.

For example, in The Irish Ecclesiastical Record in the late 19th century, the question of using unbleached candles was answered according to the rubrics at the time.

There is … a kind of congruity in using unbleached wax in the Masses de tempore in Advent and Lent … [Alban Butler] is speaking, we take it, of the Sundays from Septuagesima until Lent and as these Sundays partake of the character of the Sundays in Lent and have the same color and the same rite, what is congruous for Lent is congruous for them also. Alban Butler cannot therefore mean that there is an obligation of using unbleached wax on the occasions to which he refers, but merely that it would be more or less becoming to use it.

Using unbleached candles during Lent was never an obligation, but it was also never forbidden. Current liturgical rubrics do not mention the exact color of the candles, and the USCCB only mentions that they can not be electric lights or oil lamps.

[T]he USCCB has never employed this faculty to permit materials other than wax in the production of candles, so candles for use in the Mass and other liturgical rites must be made of wax and provide “‘a living flame without being smoky or noxious.’

Symbolism of unbleached candles

Alban Butler, in his book The Moveable Feasts, Fasts, and Other Annual Observances of the Catholic Church, briefly mentions the symbolism of these unbleached candles.

These candles are not to be white or made of blanched wax, but of common or yellow wax, as the ancient Roman Ceremonial of Bishops prescribes, because such are used by the church in times of penance or mourning, whenever she makes use of purple or black ornaments.

Generally speaking, candles represent the light of Jesus Christ, and during Lent the Church is in mourning until the great feast of Easter, when the bright white of the Easter candle is brought into the darkness of the church.

While this tradition is not widely adapted by many parishes in the world, it does provide another way to highlight the glory of Easter and to prepare our hearts for the coming feast.