Weird mark on swords 2 days after oiling

by Darian
(Canada)

QUESTION: I recently purchased my first functional katanas from musashiswords and immediately cleaned and oiled them. Two days after, I unsheathed them again to take in their beauty, but much to my astonishment there were strange marks (more like the rainbow designs seen when oil is on a wet road, just as wavy, but not the rainbow colour) on some areas of the katana. What does this mean? Did I improperly oil the katanas? Is this the start of rust?

If it helps solve this mystery, here is how I oiled my swords:
-first used lint free cotton pads to wipe off the original thick gunky oil
-then used rubbing alcohol and lint free cotton pad as a solvent to remove any missed remaining oil
-then used rice paper and light mineral oil to apply a thin layer on the entire katana blade surface

After seeing this, I was planning on cleaning and oiling them again. But since I had only oiled them 2 days ago.. so I was a bit skeptical in suspecting rust. So I touched it (i know you're not supposed to, but I was planning to completely clean and oil it again after) and it was still oily on the wavy rainbow like marks. So I re-cleaned and oiled that katana. My second katana had the same marks, this time I did not re-clean and oil, but just used some rice paper and a drop of light mineral oil over the area and the strange wavy rainbow like design dissappeared. It was only 2 days since oiling but could those marks have just been from the oil drying? or the start of rust?

ANSWER:Hi Darian,

It's not rust, but the rainbow effect you are seeing is probably some of the residual rubbing alchohol.

My advice is to wipe to sword clean with a new cloth, spray with some WD-40, wipe again and then reoil. I am pretty sure that should take care of the problem.

Hope this helps.

- Paul