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Oil black treatment..... very nice

JST

Diamond
Joined
Jun 16, 2001
Location
St Louis
A thank you to Limi Sami and Cizewski for putting me onto that process. Had a little time to try it out and got what I regard as very nice results. Did just what was suggested, heated the parts through the blue into the gray oxide, then dumped them in the oil. No hassle. Used some oil out of the misc odds and ends container, no idea what it was, looks like mostly 90 wt gear oil.

The other piece of steel is just a reference to show what regular steel looks like in the same light.





Thanks again, couldn't be easier and result looks good.
 
Yesterday, SWMBO oven roasted a chicken in a stainless pan with no lid. Chicken fat sprayed in drops onto the hot pan and left black spots that did not want to be scrubbed off with a copper mesh pot scrubber. I gave up and left some spot on the pan.

All of which suggests another way of blacking steel parts and getting a very durable finish.

Larry
 
Yesterday, SWMBO oven roasted a chicken in a stainless pan with no lid. Chicken fat sprayed in drops onto the hot pan and left black spots that did not want to be scrubbed off with a copper mesh pot scrubber. I gave up and left some spot on the pan.

All of which suggests another way of blacking steel parts and getting a very durable finish.

Larry

...And preparing a delicious roast chicken at the same time...:D
 
Almost every steel part we make gets oil blackened. Its easy and effective.:) Also gives parts a form of "wear indicator," which is handy for warrenty service. Most parts don't reqire any prep as cutting oil and coolant residue just bake off.
 
Thanks for posting your results. Since reading that thread I've been wondering just how it would look. This has always been my plan for the nuts/bolts on my 1913 Metz (car) so it is nice to know that it is going to work.
 
Since you do have to temper the parts to prety soft to do it, past blue temper, it's nit for everything. But it does look good.
 
Thanks for posting with pics JST, and I'm glad you're happy.

Just a thought -long time since I've done it, get 2 pieces of identical material leave one machined finish, one heat blacked, and one oil blacked clean em off and spray liberally with something like WD40 then leave outside but under cover, and watch how they ''weather'' over time - might be interesting and some pics would be nice ?????

:cheers: & take care

Sami
 
I made up a t-nut and stud to mount a BXA tool post on my 14" ATW's compound, I did the black oil treatment on it- came out great. I used waste motor oil from the recycle container. I didn't get the dark color, I think because the part wasn't hot enough.
 
I showed my boys that process. Generally we use old crap oil and the vapors really smell bad. Several times they have done it in the basement. Talk about something that gets momma fired up!
 
As to oil black durability I find it good for a year or two, often more, as anti rust on outdoor, garden type, jobs. Varies a lot depending on exposure and how well the black got done. Very much on par with ordinary commercial black bolts.

Lasts effectively forever inside. Got some parts I did maybe 30 years back in the workshop still looking decent.

My usual mistake is to try and run too many parts per session through a fairly small pot of oil. Once the oil gets past a bit warm the blackness tends to drop off along with level of protection. I donated a pint of fresh Castrol Magna BD 46 to my pot last time round. Somebody overfilled the P&W gearbox and something had to be done with the excess after syringing it out.

Clive
 
I was turned onto hot oil bluing years ago by someone who was helping restore an antique wagon. The first piece I did was a stamped steel trigger guard off an old Marlin .22 and the blue/black finish that resulted was IMO as good as the average factory bluing.

On the wagon they used multiple treatments of heat and olive oil that built up a weather resistant finish that was matte black and was actually more of a coating than a blue.
 
I made up a t-nut and stud to mount a BXA tool post on my 14" ATW's compound, I did the black oil treatment on it- came out great. I used waste motor oil from the recycle container. I didn't get the dark color, I think because the part wasn't hot enough.

It usually works best with an oil that smokes at a fairly low temperature.
 
One of the best I ever saw was the old black sulphurised cutting oil - well used and out of a cam auto lathe or similar, stinks worse than shit but no pain no gain.

I dunno, my neighbor bought the rear section of a Farmall M, just for a gear,
it had been sitting for a LONG time, and the oil that came out was
the blackest I have ever seen, stained your hands so bad, it was hard
to get rid to the stains even when your hands were clean.

I've seen some used oil from diesels, that where really black.

I wonder if the process could use a lower temp, if the oil is heated
to almost boiling, cold the parts dropped in, and left for 1/2 hour or so.
 
Beginner's luck!

Did a small batch, and they turned out with a clear grey. I suspect that eother the oil got too hot, (no idea why that would be an issue), or the parts were not all the way back to a steely grey after passing through boue and purple... not hot enough. But the oil sure bubbled as if it was OK.

ONE part did come out black and it was not the first one into the oil. Same material for all parts.
 
Beginner's luck!

Did a small batch, and they turned out with a clear grey. I suspect that eother the oil got too hot, (no idea why that would be an issue), or the parts were not all the way back to a steely grey after passing through boue and purple... not hot enough. But the oil sure bubbled as if it was OK.

ONE part did come out black and it was not the first one into the oil. Same material for all parts.


IME I'd say not hot enough, and not helped by cold oil.

FWIW ignoring the colour requirement, the clear grey is still a quite durable finish.
 
Funny thing.

The finish looked steel gray when pulled out of the oil. But I left them sitting to cool off and most darkened to a near-black. No idea how, or why. They were not very hot by then, but still quite uncomfortable to hold.

When they went in, they were hot enough that the oil bubbled and smoked. For the least black one, which was the first in, the oil was still bubbling when the next part went in, which was a smaller part.

SHOULD the oil be hot, or cold? You seem to suggest not cold, someone else above thought that the color was not as good after the oil was hotter.

Also: If the color is not good the first time, is there a best way to redo it? I cleaned off the first try for this small run, using detergent to remove the oil so the oil would not burn onto the surface and block oxidizing. Then I heated them to as uniform a gray oxide as possible, and dunked them again. Still got the gray color oout of the oil, but it did darken apparently just from sitting out to drain off oil.
 
Drain oil from the tractor gives the deepest color!

When the parts are large enough, and hot enough, a wonderful "open flame event" can be part of the experience.

Pyros like that a lot! '-)

Indoors, the baked and blackened oil finish lasts a life time.!
 








 
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