(It is rust blued.) The question is: What do I use to strip the existing rust blue?
Why are folks talking about all these chemicals when it's rust blue?
A sanding block and 220 grit will do fine.
Yes polishing it off works just fine.
220 will cut it off quickly. If the original polish was 320 or 400 as I usually do on rust blue,,that'd leave me with a lot of extra polishing.
Starting right in w/320 isn't too bad but the paper loads up quickly. 400 is near a waste of time over existing rust blue of any density.
Even striking it off with a file (draw file) can load the file up quickly. The beauty of a rust blued finish,,it's tough.
The need to take it all off to bright metal isn't always there however. As long as you can score through the dense rust blued surface and blend the new 'in the white' polished areas to it,,everything will re-rustblue satisfactorily and match up more often than not.
If you do want to take all the old finish off and start new,,,Chemical stripping of the bluing no matter if it's rust blue, hot salt blue or nitre or charcoal blue is also done.
It can save time and labor and an awful lot of black dust floating around.
One simple oct bbl may not be worth it,,pretty easy polishing.
Sets of SxS tubes, raised rib single bbls with attachments to polish around,,definate labor savings especially when you're looking at a bunch of work to do.
Having the 1930's coal miner face look after a day of polishing out bbl's in preparation for a run of rust bluing is not a favorite (anymore). Anything that'll get me there safer and w/less labor but keeping the same bluing results is a plus,,both for me and the customer. None of us are getting any younger!
They'll still need some hand finish polishing afterwards no matter how nice condition the base metal is. But it's a few minutes work at that point.
It's just another way to do things,,Nothing more than that.