Strange Color on knife when sanding

[xievier]

Im currently working on my first knife. I made it from a piece of scrap steel and ive done it all by grinding. I dont have a forge yet :cry: So that was the only option I had.
Im trying to polish the blade with a finishing sander and a wierd brownish color appeared on the blade as the blade became more polished. I thought at first it might be oxidation from the friction of the sander but when I felt the blade it was only slightly hotter then room temperature. I dont think its in the metal because it changes as I sand it.
I havent been able to remove it from the blade and it is frustrating me. Does anyone know what this is and how to remove it?

[dan@modernblacksmith]

gone

[T-Gold]

Could be flash rust. Happens when your surface is too clean. You can put a few drops of oil on top of your water bath, or add some baking soda, and see if this helps.