What's the best way to remove old bluing in preparation for re-bluing?

I polish it off and never bother with chemical removers.
Steve

Naval Jelly works well...may take a few applications to get really clean. For a re-bluing you will want to polish anyway so Steve's way may be best.

Phosphoric acid as in the concrete etch from Home Depot will work and it doesn't etch as much as Naval Jelly. Have a tank large enough for the part. Plug the bores and let it soak.

Steve: when you are starting with a blued gun, what's your process? Paper at 320 on up? Then soft wire wheel as with the rust blue?

For those who start with chemicals, like Mark and Sam suggested, anyone ever try something like evaporust? It's my go to for rust removal.

Post above detailing my process. Questions and comments encouraged.
Steve

Steve, if a rust-blued barrel did not need the polish, but did need to tidy up thinning blue, could you just clean it well blue over it? Seems that the well blued areas would not really change much while the thin spots caught up. Never had the courage to try this however.

Brent....that is the "old gunshow trick", Never "re-finished"...

You certainly can do that. Rust blue is a chemical process that can be stopped and started at will. It actually works quite well in certain situations, especially for small areas of repair. I do that regularly after re-attaching fore end lugs that have come loose.

In some ways it is not that different than blending an area of stock repair in to an existing finish.

Steve

I've used CLR, its mild compared to the other methods and is available at your local grocery store.

If it is still on the market, brick cleaner "Sur Kleen"(?) used full strength works immediately, but has to be washed off immediately also, or it will cause pitting. As far as bluing over old finish that doesn't need polishing, SKB is absolutely correct.
Mike

Would those acidic or other rust removal options work for hot blue, cold blue, etc? Or just for rust blued steel?

I haven't tried the phosphoric on hot blued parts so I don't know for sure. Best guess it would. Unless there is lots of pits with active rust I just polish of the old finish. Polish to 320 or 400 depending on how high a polish you want the finished product. I clean and blend by using Comet and grey scothbrite and hot water.

I have used Birchwood Casey blue and rust remover in the past. Is there a metal or finish where previous shared methods would be better than the BC option?

Looks like the BC remover is a mixture of acids according to the SDS. As far as I can tell, all rust removers are either acid (vinegar, etc) or chelators (like evapo-rust). If I'm understanding the posts here correctly, there is nothing to say that these methods wouldn't work on all the typical bluing methods.


Here's the SDS of BC rust and blue remover:

Naval Jelly (Phosphoric) works on hot dip and the various rust blues equally.

Here is an example...rust blued butt plate with bluing removed from scene. I applied Naval Jelly 3 times, washing with hot water between and then gave the scene 2 coats of Renaissance wax with lamp black added and then 2 coats without the lamp black.

Thanks Jim. That's a great looking butt plate Sam.
Scott

I've used the BC blue and rust remover as well. It seems to do a decent job of blue removal. I've used it to remove hot and rust bluing....seems to work equally well on either.

I've also just polished off the blue.

Very nice looking butt plate!

toilet bowl cleaner works good.

This has always appealed to my mean streak for removing Blue because it is cheap and works well, Distilled White Vinegar it is usually around 6% Acetic Acid so does not damage the metal.

OOps!!!