A Question on Blueing

Travis Talboys

Travis Talboys

Knifemaker / Craftsman / Service Provider
Joined
Oct 30, 2018
Messages
442
Has anyone had any issues cold blueing 52100? I'm using Birchwood Casey's, and I'm struggling to get a blotch/streak free result. I've used it before with no issues on 1084 and 1095. The steel was cleaned, then cleaned again, so it's not oils or something like that. I was just.wondering if anyone has had similar issues, or can at least explain what's going on.

Thanks in advance,
Travis
 
I like the Brownells Oxpho Blue for cold bluing. I find that the process can be a little finiky and different steels respond quite differently. I would expect 52100 to respond well given the low chromium, but I haven't tried it.

My best results are starting with a clean 400 grit finish. Wash/degrease the part. Wipe bluing on with a cotton ball. Let sit for a minute, then keep wiping and rewetting the part for 5 minutes. I used to wash in hot water between cycles but have skipped that recently. Next, lightly scrub with fine steel wool. Work on making the finish even and not blotchy, even if that means removing more of the color than you hoped. Then repeat another cycle applying with a fresh cotton ball. I usually do 4-5 cycles. Then lightly wipe with WD40 using a microfiber cloth and don't touch it for 24 hours. Hopefully it looks good by then.

The most important thing is the initial 400 grit clean finish.
 
Richard338 said:
The most important thing is the initial 400 grit clean finish.
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Perhaps that's my problem. I sanded my blade to 800 grit. I cleaned it throughly and used steel wool to blend. I repeated this several times, all with blotchy results. I even tried the method Jason Knight suggested by using a spray bottle and leaving it to sit overnight. Same results as wiping it on, but used up a lot more solution.
 
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#notaknifemaker: I have limited experience with cold blueing, but warming the surface was often recommended. Some even wet the warm surface with distilled water.
 
Steel wool has oil in it. Use a Scotch-Brite pad. Wash the pad well first.

Cleanliness is an absolute necessity. Not just washed off, but surgically clean. Try boiling the blade for 10 minutes in a solution of water and a tablespoon of TSP before a hot water rinse and bluing. Lightly scrub and rinse off between repeated bluing cycles. It can take 5-6 cycles to get it more-or-less even. Even though it is called "Col Blue", a warm blade (hot water rinse) blues better.


All that said, results will still vary. I never got what I would call a good bluing on a knife. I etch with FC.
 
Travis Talboys said:
Perhaps that's my problem. I sanded my blade to 800 grit. I cleaned it throughly and used steel wool to blend. I repeated this several times, all with blotchy results. I even tried the method Jason Knight suggested by using a spray bottle and leaving it to sit overnight. Same results as wiping it on, but used up a lot more solution.
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I only use cold blue on fittings and handle parts. I would etch in FC if you're doing the entire blade.
 
There is also the more time consuming rust blueing, if you are up for the challenge.
 
I've used Oxpho Blue with some success. As stated, perfectly clean is important. I've also found it "takes" better at a few hundred degrees. Sometimes I'll put my fittings in my oven at 250 or 300 degrees and apply the blue.
 
SharpBits said:
There is also the more time consuming rust blueing, if you are up for the challenge.
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I am, just not two weeks before a show.

Jason Fry said:
I've used Oxpho Blue with some success. As stated, perfectly clean is important. I've also found it "takes" better at a few hundred degrees. Sometimes I'll put my fittings in my oven at 250 or 300 degrees and apply the blue.
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I thought about heating slightly, but the directions call for cold water.
 
No cold blue is durable. No cold blue gives a nice finish.
Cold blue stinks. Most of the solutions simply plate a thin coating of copper sulphate on the steel. Real bluing is actually a controlled rust process.

Rust bluing is a more involved process. It's more durable than cold bluing, and looks better.

Bluing itself is a terrible finish for a carbon steel blade. No bluing is particularly durable-especially for something that is going to be rubbed while it's cutting.

Parkerizing is more durable, but will still wear.

Paints like Cerakote are more durable, but they are still paints.

PVD coating and nitriding are the only really viable options for darkening a blade. And guess what? They will wear eventually.
 
This took several 30+ minute dips in my ferric chloride, but it eventually got nice and dark! I started with a clean surface, fully degreased with Dawn Platinum, then did the 30-40 minute soaks and checked, rinsed off, and dunked again. Probably about 3-4 hours all told. I hate the smell of cold bluing, so I just acid etch instead.
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TSP is'nt what it used to be.
We used to wash walls tp paint prep when I was a kid.

The last time I used it to clean bones, it turned bones into a chalky dusty brittle mess like chlorine does.

We can still get lye in a pretty pure state in the hardware store and I think it de-greases steel without damage.
 
Bill DeShivs said:
PVD coating and nitriding are the only really viable options for darkening a blade. And guess what? They will wear eventually.
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That's just not true.
I don't even know what those coatings are - but if you want my black off - you have to grind it off.
I even buff it to a shine.
And it's not a coating.
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^no one I've seen does it better! This guy knows what he's talking about, and I for one would be happy to know some of his tips and tricks.

also, some of the coatings mentioned earlier require heat and in some cases the amount of heat it higher than the tempering temperature, so...there's that.
 
Mr. Anderson's coloring looks great. Perhaps he will share how he does it.
 
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Interesting video and great results. 292 degrees should be below the tempering temperature. Kyle Royer does some of his fittings by a similar process except that he doesn't boil it so long, presumably because his mild steel fittings blacken quickly.

One thing in the video puzzled me and that's the use of melted snow as a water source which the video implies is clean. In second grade our teacher noticed kids eating snow at recess so she had us fill a pail with the cleanest freshest looking snow we could find. Once it melted we saw how dirty and full of grit it was.
 
Dalwhinnie Single Malt is suppose to use water from snowmelt too. OK lil off topic back to your regular programming........
 
I'm very familiar with hot bluing, and it's not particularly durable.
If the blades are not hot blued, what is the process?
Or, is it a secret process?
 
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