Coating Parallels

Hello,

I have a set of Fowler Parallels (.125" thick), and every now and then when I leave them in the CNC for a longer than I anticipate, they come out with some small and very light rust spots. I hit them with some really really fine sandpaper lightly, and it goes away, so there isn't any damage to the parallels. However, it's still annoying. So my question, can we black oxide them without warping? We have a local shop that does jobs for us regularly, but they are usually a lot thicker parts, so I wouldn't know if they had any warp to them.. I do know the size change is in the millionths, so I wouldn't worry about that affecting the parallels.

I just would like some heads up if they are going to ruin my set of $350 parallels.

Thanks in advance!

You can room temp black oxide 65-85F. Your vendor should be able to confirm whether or not it will warp though.

I do believe they do heated bath I've been out there a couple of times dropping/picking up the stuff. I've never technically seen them do it though, looks like a hanger dip to be honest.