Numbers 4:13

They will remove the fat-soaked ashes from the altar and spread a purple cloth over it;

Exodus 27:1-8

"And you will make the altar of acacia wood, five cubits long and five cubits wide; the altar will be square, and its height [will be] three cubits.

Exodus 39:1

And from the blue and the purple and the crimson [yarns] they made woven garments for serving in the sanctuary, and they made the holy garments that were for Aaron, as Yahweh had commanded Moses.

Exodus 39:41

the woven garments for serving in the sanctuary--the holy garments for Aaron the priest and the garments for his sons to serve as priests.

Leviticus 6:12-13

but the fire on the altar must be kept burning on it; it must not be quenched. And the priest must burn wood {every morning} on it, and he shall arrange the burnt offering on it, and he shall turn into smoke the fat portions of the fellowship offerings on it.

Numbers 4:6-9

They will put on it a covering of {fine leather}, and they will spread a cloth of perfect blue over it, and they will place its poles.

Numbers 4:11-12

Over the altar of gold they will spread a blue cloth, and they will cover it with a covering of {fine leather} and place its poles.

Treasury of Scripture Knowledge

Summary

And they shall take away the ashes from the altar, and spread a purple cloth thereon:

The embers of the sacred fire seem to have been removed in the grate, which was carried apart from the brazen altar; both being covered from view by purple cloths

General references

Bible References

The embers of the sacred fire seem to have been removed in the grate, which was carried apart from the brazen altar; both being covered from view by purple cloths

Numbers 4:6
They will put on it a covering of {fine leather}, and they will spread a cloth of perfect blue over it, and they will place its poles.
Exodus 27:3
And you will make its pots for removing its fat-soaked ashes and its shovels and its sprinkling bowls and its forks and its fire pans; you will make all its equipment [with] bronze.
Exodus 39:1
And from the blue and the purple and the crimson [yarns] they made woven garments for serving in the sanctuary, and they made the holy garments that were for Aaron, as Yahweh had commanded Moses.
Leviticus 6:12
but the fire on the altar must be kept burning on it; it must not be quenched. And the priest must burn wood {every morning} on it, and he shall arrange the burnt offering on it, and he shall turn into smoke the fat portions of the fellowship offerings on it.

General references

Numbers 4:8
They will spread over it a scarlet cloth, and they will cover it with a covering of {fine leather}, and they will place its poles.