Rust Blue

nac7789 · Jun 13, 2021

Any tips on getting some pesky metals to rust? I have a damp box that has worked well for several receivers and barrels but for some reason I have a batch of parts that simply won't rust. I have them sanded down, stripped, coated and they've been sitting in the box @ over 100 degrees/80% humidity for 12 hours. Virtually nothing. Barrel and receiver rusted out perfectly.
The parts are all mauser; trigger, bolt shroud, bolt release, mag floor plate, bolt cocking piece.
How do I make them rust!
I'm in miami and ambient humidity is plenty high. My damp box has a heater and steamer inside. I am using rust blue german formula bluing solution.

troy fairweather · Jun 14, 2021

Try hanging them over a pot of simmering water, maybe go up a grit size.

Ryden · Jun 14, 2021

Hydrogen peroxide and table salt.

There's lots of videos on the process

nac7789 · Jun 14, 2021

Ryden said:
Hydrogen peroxide and table salt.

There's lots of videos on the process

You aren't wrong- just couldn't find any related to firearms finishing.
I have them in a box with a steamer currrently, and they are coated with a rust blue solution. Every guide I saw related to peroxide and salt recommended spraying it directly onto the items to be rusted. I assume I can just sand back down if things go sideways but is this the method you recommend? Direct application after the bluing solution? Does the bluing solution even play a part at that point?
Just curious, I googled but again found no firearm related input here. I have blued several actions but I have never strayed from the directions associated with the rust bluing. Thanks for your help!

Ryden · Jun 14, 2021

I've tried it a few times and then I just spray it on and let it rest before boiling. No bluing solution involved.

This is a shortcut to quickly get the red oxide and then it will turn black by boiling as usual.
Then card it and repeat until you get the depth of colour you desire.

I've done some knives and tools and small parts, I've been meaning to do the floor plate on my Mauser but there's always something else to be done...

For tools I no longer use this, I just drop them in the bucket of citric acid and forget them.
They come out of it rust free and with a good flat black coat of oxide.
If you just want to remove the rust, dip for a couple of hours or over night, then oil and polish.

edwardware · Jun 14, 2021

Perhaps not applicable. . . I use Laurel Mountain Forge's barrel brown to rust blue. I've been very happy with it. I go to blue a barrel band for my M70, and the darn thing makes like stainless. . . won't even discolor.

Come to find out, it's 12L* (0.15-0.35% lead) free-machining steel. It can be caustic-salt blued, but not rust blued.

nac7789 · Jun 14, 2021

Ryden said:
I've tried it a few times and then I just spray it on and let it rest before boiling. No bluing solution involved.

This is a shortcut to quickly get the red oxide and then it will turn black by boiling as usual.
Then card it and repeat until you get the depth of colour you desire.

I've done some knives and tools and small parts, I've been meaning to do the floor plate on my Mauser but there's always something else to be done...

For tools I no longer use this, I just drop them in the bucket of citric acid and forget them.
They come out of it rust free and with a good flat black coat of oxide.
If you just want to remove the rust, dip for a couple of hours or over night, then oil and polish.

Awesome thank you for your input there buddy, I will definitely give this a shot today and see if I can make anything happen! Good tips on the citric acid too btw. Going to start doing that with my oldies.

nac7789 · Jun 14, 2021

edwardware said:
Perhaps not applicable. . . I use Laurel Mountain Forge's barrel brown to rust blue. I've been very happy with it. I go to blue a barrel band for my M70, and the darn thing makes like stainless. . . won't even discolor.

Come to find out, it's 12L* (0.15-0.35% lead) free-machining steel. It can be caustic-salt blued, but not rust blued.

This is what I was somewhat concerned about- definitely must be some sort of different alloy given that they were all prepped together and the barrel/receiver rusted out perfect and these are yet to budge after a full 24 hours in the damp box.
I'm going to try the method above with the peroxide and vinegar. If that doesn't work I'll look into a small nitre blue operation to setup. Looks pretty straight forward just a little involved and perhaps risky with the whole molten sulphur eruption stuff. Thanks for sharing!

troy fairweather · Jun 14, 2021

Sounds like it's high in nickel, so hot bluing won't work to sell either, parts may come out reddish or Purply. I use the pinkertons solution and has always worked, some metal parts just take forever. Sometime I'll heat blue Stubborn parts, I've seen were parts that are case hardened won't rust blue.

wiscoaster · Jun 15, 2021

Oven.

(PS - probably n/a for rifles, unless you've got a pizza-shop sized oven!! ... but, running boiling water down the barrel doesn't work all that bad, either; been there, done both.)

(PPS - If you're married, be prepared for some outrageous excuses and promises of cleanup!!)

Rust Blue

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