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Metal blackening

Janger

Janger

(John)
Vendor
Premium Member
Hi,
I've been trying to understand black oxide treatments of various kinds for ferrous metal. I see the "hot" black oxide method is traditional, effective, and sounds like a big pain with heated tanks and endless buckets of goo. Good for an assembly line, not good for me with just a few parts at a time.

I've tried "Jax Black" and really don't like the results. Just looks like I put the mill scale back on along with some rust.

Has anyone tried these various cold oxide treatments? Or something similar?

gel type:
http://www.caswellcanada.ca/shop/product.php?productid=29709&cat=128&page=1
room temp type:
http://www.caswellcanada.ca/shop/black-oxide-kit.html

fancy ?
Insta-Blak 333 Blackener

also fancy ?
http://www.epi.com/c/black-oxide/steel/room-temperature-black-oxide
 
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Here's a couple of shots. One is before Jax Black, the clean bright steel. The second is after Jax Black, the one that looks rusty and awful. lilke I put the mill scale back on and salted it.
 

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I haven't tried any blackening yet but i have been thinking about it allot. Have you talked to Alberta plating about prices for zinc plating? I had some home made tools brass plated there and they did a really nice job.
 
Some before/after pics of my milling machine X-stop parts made of plain CR steel. Its generic blackening stuff from KBC, kind of a transparent blue liquid. It works OK, so-so, mostly I do it just to prevent rust. Parts need to be completely degreased (brake cleaner). The better the machine finish, the better it looks. I find a couple of dip/dry/wipe/repeat treatments helps. Instructions say to rinse under water but I found it doesn't really do anything beneficial & actually risks making it blotchy with a redish rust. Maybe they mean distilled water? After my black final dip & wipe I just rub it with WD40. Don't know why but it seems to work. They do sell a sealer but I'm not sure what's in it. The blackening isn't very penetrating so if you hard scratch it, it will show. I have also re-blackened with mixed success. If its to cure a missed area or blemish its ok. An old part that's been in service, nyeahhh.. I think oils is the culprit.
 

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Yes that looks like the brand. But I just got the blackening component, not the cleaner/sealer kit. I recall the blackener was ~35$ for a litre back in the day You might also want to try Kens Gems. He sells smaller quantity metal patinas for other alloys & I recall seeing one for steel.Guessing its the same stuff. I've also seen a gun blue/black repair kit size at Wholesale sports in the gun section, but it struck me as spendy for small qty. Maybe if you just want to try though. I only do small parts here & there so this should last a while. After it reacts to steel it goes a turd color & loses ability to blacken. So you have to dispose as spent. I swab it on with one of those foam brushes & try use the new stuff sparingly.

My understanding (might be wrong) that the gel is used for spot repairs & irregular parts you cant normally dip. I think that Caswell or one of the coating places has a forum where I read that.

I've also seen some parts that looked as good (maybe better) where the guy oven heated steel it & dipped in oil. I have a small toaster oven in the shop that goes to 475F or so & gave a try on some scrap parts. It kind of worked but with all the rigmarole & smoke... the cold dip was just easier. Actually I should mention spray bomb engine enamels can give much better aesthetic results & there are some you post heat so they are very tough. But if you are trying to hold dimensions or have hole/thread features or concerned they may chip with use or flake off under say clamping, the black dip is pretty easy.

Also, I had HORRIBLE experience with the black or blue intended for aluminum. The part looked real good sitting in the liquid, when I pulled it out it just got ugly. Almost like a weird velvet texture & it smeared off quite readily. I cleaned the aluminum spotty good with various types, alcohol, acetone, brake cleaner, tried pre-heating... same ugly part every time. One of you smart guys needs to build an anodizing system, I think that's the proper way to go on aluminum.
 
My own view is blackening helps slow normal rusting, but its not permanent. I read somewhere that the blacking is a form of oxide, not unlike regular rust, but different composition. Its probably getting the most corrosion resistance from the sealant/oil. My own theory is the blackening whatever, chemical or carbon from oil, sticks pretty well to the bare metal. Even though its very thin, its kind of like a matt primer coat substrate that gives the oil something to absorb into. This link talks about some aspects of the oil dip. They also mention another technique where they bake the metal all wetted with oil. The smoke would probably be even worse than dipping.
http://www.practicalmachinist.com/vb/general-archive/oil-blackening-rust-protection-84713/
 
I totally forgot about Jangers nice anodizing. I think the summer outside my shop is starting to bake my brain.
 
Here are some examples of blackening I did via hot oil dip:
2015-05-18 17.36.20.jpg 2015-05-18 14.36.28.jpg 2015-05-18 14.35.41.jpg
In hind site I think it may have been metal bluing via the temper color chart, but I don't really remember the procedure that well. (First lathe project ever)
 
Coincidentally on another forum a guy just finished a nice tool. I asked about his method & he replied:
The process is very simple but effective , The part needs to be cleaned , then cleaned some more with Acetone of some other such cleaner that will remove all traces of oil and grease /finger prints so were gloves when handling the part , then the part is heated up slowly and EVENLY , most reach for the propane touch , me I prefer to use a cheap heat gun , the type used for stripping paint .
Work the heat evenly over the part until the desired colour is achieved , from straw yellow through to purple (the tempering) colours . Whats happening is an oxide layer is being built up on the part as it is heated .
 

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There is an interesting video by the welding tips and tricks guy Jody showing Caswell brand black oxide being applied. The video starts with TIG welding parts and is interesting but if you don't care the Black Oxide application starts at about minute 8:02. The results look nice and not too complicated a process.

 
Interesting. That pale blue blackening liquid visually looks identical to what I'm using from KBC. I know that's not really a confirmation its the same chemically, but just say'n. I also experimented with heating the part using my heat gun. I cant say it came out any more even looking or resistant, but I've heard that it helps on other forums. I do think there is something to the surface prep & maybe the blasting conditions it a bit better to absorb. I never sprung for the dedicated sealer. Does anyone have any results of it vs. other methods? I also read somewhere they can have light waxes in there. I tried some aerosol, what is essentially wax based mold release. It lustred a bit better but I really cant seeing it staying put for very long. And anything like that would just require more work to remove if you ever wanted to tune up the surface later. Just a thought - I might be wrong.
 
So that blue liquid in the video is also identical in appearance to the "jax black" I bought at Kens gems which has given me such poor results. But I didn't clean it other than with the angle grinder and the part wasn't heated like in the vid in the hot cleaning bath or hot rinse after. Those cleaning and temp details made a big difference with the anodizing I was experimenting with. Maybe a test with hot degreasing bath NaSOH lye and warm blue jax black and a warm rinse.
 
According to that little German dude on YouTube if you can heat your parts to something like 350f it takes all the moisture and then burns off any hydrocarbons.. If you haven't watched his videos I'd suggest it.. But the one about painting covers it.
That may be helpful when doing this, his reasons for doing it is the single atom layer of hydrocarbons that is left and fucks up painting, may apply in this instance as well.

Here's the first one
 
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