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Old August 3rd 08, 01:30 PM posted to uk.d-i-y
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Default Blueing/oil quenching of mild steel

When I was a lad, if memory serves correctly, we used to dip hot ferrous
parts into a bucket of old engine oil. This gave them a blue/black
finish and I'm pretty sure we called it "blueing".

Anyway, I've been Googling and I'm a bit confused, cos blueing seems to
be a rust-proofing process which does not involve oil and oil-quenching
is a hardening process, not a rust-proofing process.

Can anyone put me straight? I was idly thinking about DIY oil quenching
to achieve moderate rust-resistance.

Do I need to use old engine oil, or will new be good/better/safer?

ISTR we heated the parts up to a dull red before quenching. Does this
sound right?


Cheers,

Rumble

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Old August 3rd 08, 01:40 PM posted to uk.d-i-y
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Default Blueing/oil quenching of mild steel

Dave Osborne wrote:
When I was a lad, if memory serves correctly, we used to dip hot ferrous
parts into a bucket of old engine oil. This gave them a blue/black
finish and I'm pretty sure we called it "blueing".

Anyway, I've been Googling and I'm a bit confused, cos blueing seems to
be a rust-proofing process which does not involve oil and oil-quenching
is a hardening process, not a rust-proofing process.

Can anyone put me straight? I was idly thinking about DIY oil quenching
to achieve moderate rust-resistance.

Do I need to use old engine oil, or will new be good/better/safer?

ISTR we heated the parts up to a dull red before quenching. Does this
sound right?


Cheers,

Rumble

from memory quencing in engine oil adds carbon and surface hardens the
steel, old oil has more carbon and therefore hardens more, I did this as
an apprentice years ago and i seem to remember they still rusted

--
Kevin R
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Old August 3rd 08, 01:57 PM posted to uk.d-i-y
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Posts: 339
Default Blueing/oil quenching of mild steel

In message , Kevin
wrote
Dave Osborne wrote:
When I was a lad, if memory serves correctly, we used to dip hot
ferrous parts into a bucket of old engine oil. This gave them a
blue/black finish and I'm pretty sure we called it "blueing".
Anyway, I've been Googling and I'm a bit confused, cos blueing seems
to be a rust-proofing process which does not involve oil and
oil-quenching is a hardening process, not a rust-proofing process.
Can anyone put me straight? I was idly thinking about DIY oil
quenching to achieve moderate rust-resistance.
Do I need to use old engine oil, or will new be good/better/safer?
ISTR we heated the parts up to a dull red before quenching. Does
this sound right?
Cheers,
Rumble

from memory quencing in engine oil adds carbon and surface hardens the
steel, old oil has more carbon and therefore hardens more, I did this
as an apprentice years ago and i seem to remember they still rusted


From my often faulty memory from 40 odd years ago, wasn't blueing also
just an aid for 'marking out' the work. An easily removable dye gave a
blue surface colour on the 'shiny' metal on which you could scribe out
lines, by cutting through the dye so that you could easily see them..
--
Alan
news2006 {at} amac {dot} f2s {dot} com
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Old August 3rd 08, 02:12 PM posted to uk.d-i-y
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Posts: 305
Default Blueing/oil quenching of mild steel

Alan wrote:
In message , Kevin
wrote
Dave Osborne wrote:
When I was a lad, if memory serves correctly, we used to dip hot
ferrous parts into a bucket of old engine oil. This gave them a
blue/black finish and I'm pretty sure we called it "blueing".
Anyway, I've been Googling and I'm a bit confused, cos blueing seems
to be a rust-proofing process which does not involve oil and
oil-quenching is a hardening process, not a rust-proofing process.
Can anyone put me straight? I was idly thinking about DIY oil
quenching to achieve moderate rust-resistance.
Do I need to use old engine oil, or will new be good/better/safer?
ISTR we heated the parts up to a dull red before quenching. Does
this sound right?
Cheers,
Rumble

from memory quencing in engine oil adds carbon and surface hardens the
steel, old oil has more carbon and therefore hardens more, I did this
as an apprentice years ago and i seem to remember they still rusted


From my often faulty memory from 40 odd years ago, wasn't blueing also
just an aid for 'marking out' the work. An easily removable dye gave a
blue surface colour on the 'shiny' metal on which you could scribe out
lines, by cutting through the dye so that you could easily see them..

that was engineers blue

from the web
Prussian blue is mixed with methylated spirits it forms a quick drying
stain which is known as marking blue or layout dye. This stain is used
in the marking out operation in metalworking.

--
Kevin R
Reply address works
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Old August 3rd 08, 02:38 PM posted to uk.d-i-y
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First recorded activity by DIYBanter: Jul 2006
Posts: 2,112
Default Blueing/oil quenching of mild steel


"Kevin" wrote in message
...
Dave Osborne wrote:
When I was a lad, if memory serves correctly, we used to dip hot ferrous
parts into a bucket of old engine oil. This gave them a blue/black
finish and I'm pretty sure we called it "blueing".

Anyway, I've been Googling and I'm a bit confused, cos blueing seems to
be a rust-proofing process which does not involve oil and oil-quenching
is a hardening process, not a rust-proofing process.

Can anyone put me straight? I was idly thinking about DIY oil quenching
to achieve moderate rust-resistance.

Do I need to use old engine oil, or will new be good/better/safer?

ISTR we heated the parts up to a dull red before quenching. Does this
sound right?


Cheers,

Rumble

from memory quencing in engine oil adds carbon and surface hardens the
steel, old oil has more carbon and therefore hardens more, I did this as
an apprentice years ago and i seem to remember they still rusted


No, it's the quenching (i.e. rapid cooling) which hardens the steel, as long
as
it contains enough carbon. For surface hardening you need to heat the steel
to
red heat in a carbon rich source for long enough for carbon to diffuse into
the
surface, and then you quench it. Look up case hardening.

Oil quenching is faster and better controlled than water quenching because
you don't get the steam blanket, so it is more commonly used in industry,
also
it is better for some alloy steels.

You'll get some rust resistance from hot quenching, and more from proper
chemical blue or chemical black treatments as used on guns, for example.
Lots of proprietary suppliers or you can mix your own. Look up chemical
black
or blue




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Old August 3rd 08, 02:43 PM posted to uk.d-i-y
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Default Blueing/oil quenching of mild steel


"Kevin" wrote in message
...
Alan wrote:
In message , Kevin
wrote
Dave Osborne wrote:
When I was a lad, if memory serves correctly, we used to dip hot
ferrous parts into a bucket of old engine oil. This gave them a
blue/black finish and I'm pretty sure we called it "blueing".
Anyway, I've been Googling and I'm a bit confused, cos blueing seems
to be a rust-proofing process which does not involve oil and
oil-quenching is a hardening process, not a rust-proofing process.
Can anyone put me straight? I was idly thinking about DIY oil
quenching to achieve moderate rust-resistance.
Do I need to use old engine oil, or will new be good/better/safer?
ISTR we heated the parts up to a dull red before quenching. Does this
sound right?
Cheers,
Rumble
from memory quencing in engine oil adds carbon and surface hardens the
steel, old oil has more carbon and therefore hardens more, I did this as
an apprentice years ago and i seem to remember they still rusted


From my often faulty memory from 40 odd years ago, wasn't blueing also
just an aid for 'marking out' the work. An easily removable dye gave a
blue surface colour on the 'shiny' metal on which you could scribe out
lines, by cutting through the dye so that you could easily see them..

that was engineers blue

from the web
Prussian blue is mixed with methylated spirits it forms a quick drying
stain which is known as marking blue or layout dye. This stain is used in
the marking out operation in metalworking.

--
Kevin R
Reply address works


Not what the person is wanting - he is looking for an effect similar to that
found on a gun barrel.

I recall processes such as Parkerising and Walterising - better than just
blacking with oil.

I have a scribing block I made as an apprentice which is still a nice
black - it was Parkerised.



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Old August 3rd 08, 03:50 PM posted to uk.d-i-y
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Posts: 357
Default Blueing/oil quenching of mild steel

Dave Osborne wrote:
When I was a lad, if memory serves correctly, we used to dip hot ferrous
parts into a bucket of old engine oil. This gave them a blue/black
finish and I'm pretty sure we called it "blueing".


I remember doing this at school, too. This was recently enough for the
subject to be called "Design and Technology (Resistant Materials)", but
was essentially still metalwork taught in the metalwork workshop by
crusty old metalwork teachers :-).

Can anyone put me straight? I was idly thinking about DIY oil quenching
to achieve moderate rust-resistance.


The other day in my dad's garage I came across the mild steel gadget
that I made in 3rd-form DT. The surface didn't look all that great
(probably didn't when new either :-) ), but it wasn't rusty. So I reckon
"moderate rust-resistance" is about right.

Do I need to use old engine oil, or will new be good/better/safer?


I do remember the aforementioned crusty old teacher telling us that the
older the oil, the better.

ISTR we heated the parts up to a dull red before quenching. Does this
sound right?


I think so.

Pete
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Old August 3rd 08, 11:12 PM posted to uk.d-i-y
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Posts: 5,180
Default Blueing/oil quenching of mild steel

On 3 Aug, 12:30, Dave Osborne wrote:
When I was a lad, if memory serves correctly, we used to dip hot ferrous
parts into a bucket of old engine oil. This gave them a blue/black
finish and I'm pretty sure we called it "blueing".



Hot oil: Heat them up (not glowing) and wipe with oil. Vegetable oils
give browns, clean engine oil gives blues, old engine oil gives black.
Not rustproof against weather. You only need a gas blowtorch to heat
the steel up, then wipe with an oily paper towel. Use paper, as it's
easier to extinguish than rags. Wear a good leather welder's glove
when doing this, and not one with a hole in!

Cold blues: Selenium compounds. Phillip's is best (gunshop),
Birchwood Casey a long way behind. Follow instructions. Cleanliness
and degreasing with acetone is vital. Toxic. Not rustproof.

Browning. Controlled rusting to give the finish of old steelwork or
shotguns. Read a pre-war gunsmithing book. Harder than it sounds to
get good results.

Weatherproof bluing. Look up "Parkerising", buy the kit from Caswells.
Complicated.


Hardening, tempering and quenching relies on using a steel with some
useful amount of carbon in it, not mild steel. Carbon won't migrate
from an oil quench. For a good text on hardening, knifemaking books
from Barney & Loveless (cheap), Wayne Goddard or Jim Hrisoulas
(excellent) are good primers. 1950s engineering textbooks are pretty
good too. Weyger's book is crap.

If your steel has insufficient carbon to start with, add some by case-
hardening. The wikipedia article is decent.


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