Selvage and selvedge mean exactly the same thing - different companies spell it differently and there apparently is no "right" way to spell it. It comes from the phrase "self-edge" which refers to the edge being finished by the loom instead of sewn together after weaving. thanks Geowu
. Selvage is the term commonly used to refer to denim that has been produced on a shuttle loom. Since the amount of fabric produced from a shuttle loom is significantly narrower than a projectile (wide) loom, the cotton consumption is higher and the time required is greater. In selvage jeans, you will see the actual edge of the fabric where the weaving stops and is finished by the loom, as opposed to denim woven on a projectile loom, where the fabric has been cut off at the ends. The "redline" selvage is Levi's signature and was used in all their jeans up to 1982, before Cone Mills nixed them for the more modern projectile looms, which are faster and much more efficient.
I've sold brand new raw selvedge Evisu's