The Priestly Robes were white, they were to remain brilliantly white at all times. They were an integral part of the his covering which allowed him into the presence of the Most High.
Exodus 28:4 “And these are the garments which they shall make; a breastplate, and an ephod, and a robe, and a broidered coat, a mitre, and a girdle: and they shall make holy garments for Aaron thy brother, and his sons, that he may minister unto me in the priest‘s office.”
This was not done to excel them above anyone else, nor to magnify their authority, it was, to make them presentable before YHWH.
The significance for us today lies in the concept of a covering acceptable to YHWH. This is, as many Christians have come to know, is the Marriage Covenant secured through Yahshua the Messiah.
Ephesians 5:27 “That He might present it to Himself a glorious church, not having spot, or wrinkle, or any such thing; but that it should be holy and without blemish.”
The part of the story often untold is what happened to the robes that became spotted?
The priests went to extraordinary lengths to keep them clean. The robes were not on shelves or racks at the local department store. There were thousands of priest in all shapes and sizes, so, these were custom made.
Even after their best effort, due to the fact they were handling animals that were being butchered (like the local grocer) to be put on a burning altar, they would be covered in blood.
The bloody robes would then be washed but still stained by the blood. After washing they would be torn into strips of cloth for other uses., such as, wrapping the bodies of the deceased.
Yahshua, our Messiah, would have been cared for in the same way. He would have been wrapped in the cloth stained by the blood of sacrifice while He was offering Himself as our sacrifice.
Revelation 7:13-14 “And one of the elders answered, saying unto me, What are these which are arrayed in white robes? and whence came they? And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb.”