Construction (Exodus 30:17–21)
"Thou shalt also make a laver of brass, and his foot also of brass, to wash withal: and thou shalt put it between the tabernacle of the congregation and the altar, and thou shalt put water therein. For Aaron and his sons shall wash their hands and their feet thereat: when they go into the tabernacle of the congregation, they shall wash with water, that they die not; or when they come near to the altar to minister."
Bronze, like the altar — judgment-metal. No specified dimensions; the size was apparently left to artisan judgment. The laver had a basin and a foot (a base) — both of bronze. Water filled it; the priests washed there.
The mirrors of the women
"And he made the laver of brass, and the foot of it of brass, of the lookingglasses of the women assembling, which assembled at the door of the tabernacle of the congregation" (Exodus 38:8). Ancient mirrors were polished bronze, not glass. The women who served at the entrance of the tent of meeting brought their personal mirrors and gave them. From those mirrors the laver was cast.
The instrument of self-examination became the instrument of cleansing. The thing once used to study one's own face was melted down to hold the water that washed feet. Henry (PD): the women parted with their ornaments to advance the work of God; the very glass that fed their vanity now nourished a higher service. The progression is theological — what is laid down in worship returns as means of grace.
Purpose — wash, or die
The text repeats the warning twice in five verses: "that they die not" (Exodus 30:20–21). This is not metaphor and not exaggeration. The unwashed priest who entered the tent or approached the altar would not survive the encounter. Holiness is not an aesthetic preference of God; it is a structural reality of his presence. Approach without cleansing was as fatal as approach without sacrifice.
Position — between the altar and the tent
The laver stood between the Bronze Altar and the entrance to the Holy Place. Cleansing follows sacrifice. The laver is not the place where one gets righteousness — that happened at the altar. The laver is where the priest, already accepted on the basis of the blood, washes for ongoing ministry. Daily washing follows once-for-all sacrifice.
The typological argument
Ephesians 5:25–26 — "that he might sanctify and cleanse it with the washing of water by the word." Christ sanctifies the church by water and word — a clear gesture toward the laver. John 13:1–11 — Jesus washes the disciples' feet at the Last Supper, and Peter's objection prompts a precise statement: "He that is washed needeth not save to wash his feet, but is clean every whit." The Greek distinguishes the bath (leloumenos) from the foot-washing (niptō). The believer has had the bath of justification; the daily washing of sanctification is the foot-laver of the Christian life. Titus 3:5 — "the washing of regeneration" — names the same act under a different angle.
The laver, then, is what the believer returns to between justification (altar) and ministry (the Holy Place). The blood was once-for-all; the washing is daily.
Commentary
Matthew Henry, Exposition (PD): the laver was filled with water that the priests might wash often, signifying the believer's perpetual need for cleansing by the Word and the Spirit. John Calvin, Institutes IV.15: ministry-grade cleansing is a particular work of the Word; the laver is not the sacrament of regeneration but the daily instrument of the Word's ongoing application.
→ Cross-link: The Bronze Altar (cleansing follows sacrifice) • The High Priest (consecration washing) • The Day of Atonement (priest's preparation).