Charles Ellicott Commentary Exodus 29:36

"And every day shalt thou offer the bullock of sin-offering for atonement: and thou shalt cleanse the altar, when thou makest atonement for it; and thou shalt anoint it, to sanctify it." — Exodus 29:36 (ASV)

You shall cleanse the altar, when you have made an atonement for it. —Rather, by making an atonement for it. The atonement was made by smearing the blood of the bullock upon the horns of the altar (Exodus 29:12, compared with Leviticus 8:15).

And you shall anoint it. —Compare Leviticus 8:11, where we find that the altar was anointed by having the holy oil sprinkled upon it seven times. It is not quite clear at what period in the ceremonial this was done.