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Thread: 1 Hour Red Rust Bluing (DIY Black Oxide for your tools)

  1. #1

    1 Hour Red Rust Bluing (DIY Black Oxide for your tools)

    Hi everyone,

    I do a number of wood and metal working projects (I'm a really green wood worker but I hope to build up my skill). Over the years I have deal with the rust issue due to working in a humid climate.

    I have some older wood working hand tools that I would like to refinish. I've been doing some reading on various processes used to provide a protective coating. Specifically I was looking for a process that I could easily do in the home shop. I've been thinking about buying some cold blue and I was just about to until I started reading about some of the rust bluing processes. The only problem was that traditional rust bluing takes a long time.

    I did some more reading and I recalled an experiment we did in high school chemistry involving a mixture of hydrogen peroxide and salt applied to steel wool. The hydrogen peroxide and salt rusted the steel wool so quickly that you could measure the temperature change. I then did some further searching and I found someone beat me to the idea of quickly rusting parts using hydrogen peroxide and salt: http://mypeculiarnature.blogspot.ca/...-in-black.html

    I tried it out on some vise clamps I made (I didn't want to do it immediately on my set of older chisels in case it didn't work), it took only about an hour or so, and I'm very pleased with the results:


    viseclamps-lowres1.jpg

    I also made a video out of the process as a sort of instructions:



    Here is the direct link if you wish to watch it via Youtube's site: https://youtu.be/xmv58Z3RZ9c

    Hopefully this helps anyone with a future project they want to protect from rusting.

  2. #2
    Thanks. Very cool. I will try this out. No doubt it's way more reliable and durable than "cold blue" - which often looks funny to me..

    An old fashioned way to do this (slower and without the salt) is to clean the parts very well and then use a wet box to rust them... It's just high humidity... Then just boil as shown to turn it black..

    I have also gotten good results by just torching rusted parts... The red rust turns to black rust and off you go.. Just don't do it with heat treated parts...

  3. #3
    Join Date
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    Howdy Justin and welcome to the Creek.

    Neat idea for rust prevention.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  4. #4
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    Thanks for the video, those parts turned out nicely. I've rust blued a bunch of tools and tool parts over the past year or so- I like the look and it improves the appearance of mangy old tools. I started out using the peroxide-salt mixture, inspired by the same blog. It does work, but I had some issues with getting an even coloring on some parts. Particularly some Japanese blades- the hard high-carbon steel would blue nicely but the soft steel/iron would not. It also caused tiny pitting- nothing major like you'd find on an old rusty tool, but I noticed it when I had to polish the backs of chisels that had been rust blued. It took a few minutes on a 1000 grit stone to get through it.

    I ended up doing enough blue-ing that I decided to try a bottle of Pilkington's rust blue. This seems to be recommended by gunsmiths for firearm restoration. It is less aggressive than the salt/h2o2 mixture- no foaming, no instant dramatic rusting. You let it sit out an hour or two and it just kind of discolors, with a very thin layer of surface rust. But when you boil it for 10 minutes the color forms nicely. It takes 3-5 iterations before you hit diminishing returns, so the process is done over a couple of days usually, though it is still not that much labor. Overall the color was more even, with no mysterious areas that didn't turn. And when polishing the backs of blades there were no visible pits, so there is less metal to remove to get the tool back into shape- especially important on japanese blades where you don't want to increase the lands on the back.

    I'm curious about your comments on Hydrogen embrittlement being a potential hazard when rust-blueing hardened steel. Most of the parts I've done have been chisels and plane irons- so far I have not had issues. Can you elaborate on what would cause embrittlement and how to avoid it?

  5. #5
    Thanks Justin, that looks great. Something to try again.

  6. #6
    Thanks everyone!

    Quote Originally Posted by Robert Hazelwood View Post
    I'm curious about your comments on Hydrogen embrittlement being a potential hazard when rust-blueing hardened steel. Most of the parts I've done have been chisels and plane irons- so far I have not had issues. Can you elaborate on what would cause embrittlement and how to avoid it?
    Hydrogen embrittlement is caused when hydrogen atoms deposit themselves into the molecular lattice of the steel. It does exactly what it sounds like - makes the steel very brittle and cause cracking. The hydrogen is from moisture in the atmosphere - although just the atmosphere conditions alone are usually not enough to cause the problem. More often it happens when water is directly involved in a process.

    Hardened steel is particularly susceptible to it. It is a common problem in welding hardened plate (often times a shop will bring in steel that has been sitting outside in the rain and weld it). In these cases it often cracks within a very short period of time after welding - cracks can show up in as little as 4 hours. It is also a problem in the plating process (like zinc plating). High strength bolts (ie Grade 8) are susceptible to hydrogen embrittlement when they are zinc plated. The zinc plating process uses a significant amount of water in various stages.

    To prevent it you simply need to bake the parts (a common household oven will work) for a few hours after the plating process, or whatever process you are doing. Not at a high enough temperature to temper the parts.

    I've seen a number of hydrogen embrittlement failures. Most cases it involves newly formed products (ie just welded, bolts that were just manufactured and then plated).

    Hydrogen embrittlement in older steels I think isn't as common for some reason, although it could still happen. If you are worried about it an hour bake in the oven at around say 250 - 300 degrees F will significantly reduce the risk. It is also much more problematic in through hardened parts, case hardening isn't as much of a problem. And the softer the part (the clamps I made were not hardened whatsoever) the problem is much rarer.

  7. #7
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    The reason professional metal finishers use chemicals like Pilkington, or homemade brews based on partially-neutralized nitric acid, is that the oxidation process is predictable, and easy to stop. These mixtures never contain salt.

    The problem with salt is that the chlorine it contains bonds with the iron, and continues oxidation for a long period of time. Indeed, it is very difficult to stop, and will cause pitting to develop long after the desired effect is achieved.
    Last edited by Stanley Covington; 03-12-2018 at 9:38 PM. Reason: Stuttering

  8. 2 year update?

    Quote Originally Posted by Stanley Covington View Post
    The reason professional metal finishers use chemicals like Pilkington, or homemade brews based on partially-neutralized nitric acid, is that the oxidation process is predictable, and easy to stop. These mixtures never contain salt.

    The problem with salt is that the chlorine it contains bonds with the iron, and continues oxidation for a long period of time. Indeed, it is very difficult to stop, and will cause pitting to develop long after the desired effect is achieved.
    Hi all, going through this rust bluing process with some old tools and I'd love your thoughts on this quote from Mr. Covington. With the possibility of the chlorine causing continued oxidation over a long period of time, maybe Mr Siemens could give an update on these machine clamps after 2 years and see whether he has noticed any continued pitting or continued oxidation on these parts?

    Thanks!

  9. #9
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    Wouldn't hold your breath. Justin was only around for 2 weeks, and that was almost 3 years ago.

  10. Ah, gotcha, appreciate the quick response and the candor!

  11. #11
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    Quote Originally Posted by Christopher Olsen View Post
    Hi all, going through this rust bluing process with some old tools and I'd love your thoughts on this quote from Mr. Covington. With the possibility of the chlorine causing continued oxidation over a long period of time, maybe Mr Siemens could give an update on these machine clamps after 2 years and see whether he has noticed any continued pitting or continued oxidation on these parts?

    Thanks!
    Not the OP, but the first batch of tools I rust blued were done with a salt/hydrogen peroxide mixture, about 3 years ago. I still use most of these tools frequently, and they are not forming rust or pitting that I can see. To be clear, there was some minor pitting created during the rusting, which is not noticeable on the blued areas, but where I needed to remove the blueing by abrasion (as on the back of a chisel) you could see pits (deeper black areas) that too a little more work to get out. But after the blueing process was completed, I have not noticed any further corrosion.

    The Pilkington's solution does not cause as much (if any) pitting, and in general creates a more even coating of surface rust, which yields a better looking rust blue. But the H202+Salt does work

  12. #12
    Brownell's, Inc., a gunsmithing supply outfit in Montezuma, IA, sells a cold blue product called OxphoBlue. I've had good luck with it over the years.

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