I've been waiting for the linseed oil I put on a new one's handle to dry before I took the paper and tape off the blade.  Finally did yesterday and the first thing I noticed was rust on both sides of the blade and across the spine right where the scales meet up.  After I sanded the blade I put a good coat of WD 40 on it to keep the rust off, but before I put the scales on I wiped the tang down good with acetone to get rid of it.  My only guess is I got a little careless with the acetone and took some of the WD 40 off the blade, too.  I'm guessing I'm stuck sanding it all off, but if anybody has a better idea I'd love to hear it.

What kind of tape did you use?

I used duct tape, but didn't apply it directly to the blade.  I wrapped the blade with construction paper, mostly because my son had left some laying in the garage, then secured that with duct tape.

OK, I'm not saying I know what caused it. I'm just trying to help. But, the construction paper might react with the WD-40 and cause some problems. Dont know. I use WD-40 for clean up, but I use shop towells and painter's tape to cover the blade. The blue towells and tape from Walmart. I have not had any problem, but I put Ballistol on the towell.

Thanks Lin, I'll give that combo a try on the next one.  I'll try to get a photo of what happened up later.