Pendleton Woolen Mills bought Columbia Wool Scouring Mills in 1971. If this building is still in use, they receive raw wool fiber in fleece form here where it's graded, sorted and scoured, which is a washing process. So sometime between the sheep and your comfy blanket, the fleece/wool probably goes through this building.
The sign is quite easy to see at 2030 N. Columbia Blvd. You can also see it from the MAX train or crossing N. Denver.