Hi gang, We just wrapped up a delightful week of Knifemaking with Tim
McCreight here. He’s an inspiring teacher! We used O1 tool steel and
hardened it in motor oil. What kind of oil do you all use to harden
steel? (I am looking for something that won’t go rancid and smells
better than motor oil). Thank you! Kate Wolf in drizzly Portland,
Maine http://www.katewolfdesigns.com
I use olive oil for quenching steel. A tip courtesy of Valentin
Yotkov. The steel I am using is Sheffield steel. Natasha Wozniak
Kate, I just completed a Northwest Coast-style carving tool class
taught by noted author and artist, Steve Brown. We used mineral oil
to harden our tools. It had very little odor and shouldn’t turn
rancid (I don’t think motor oil will either, but certainly some
vegetable oils could). We were quenching bent knives as well as
adze blades, so we used two gallons in a galvanized bucket. I think
if you were quenching small knives only, you wouldn’t need as much
oil.
Good Luck,
Chris Hanson
Abo Originals
Ketchikan, AK
Hi gang, We just wrapped up a delightful week of Knifemaking with Tim McCreight here. He's an inspiring teacher! We used O1 tool steel and hardened it in motor oil. What kind of oil do you all use to harden steel? (I am looking for something that won't go rancid and smells better than motor oil). Thank you! Kate Wolf in drizzly Portland,
Kate, there is a fine interaction between the type of steel and the
speed which it must be cooled to obtain the desired hardness. The
oil hardened steel needs the slower cooling process obtained with an
oil. You could use water, but it might over harden and even crack
the steel. There is basically three types of steel which can be
hardened by heat treatment. They are Water Harden, Oil Hardened,
and Air Hardened, listed in the sequence of cooling times, with the
Water being the fastest. There are many sub types in each group.
How does this apply to your question? Well I guess that I am
pointing out that the type of oil used is important to obtaining the
desired hardness. The amount of oil in relationship to the piece
and the starting temperature are all a part of the equation. Motor
Oil, SAE 30 with no additives (hard to find now) is the most
generally used quenching oil. It is also sometimes desirable to
pre-heat it to 100 to 150 degrees for the best results. While other
oils will work, olive oil has been suggested, they might not give
the optimum results. There is also the question of Flash Point.
Some other oils might actually flame up when presented I have never
been in a blacksmiths shop that smelled good, although the odors to
bring back some good memories. You will be doing a limited amount
of heat treatment of steel so why not There is a book I used while
on an apprenticship several years ago called Elements of Heat
Treatment. It gives a very good description of ways to harden
metals, although it talks almost exclusively to steel and iron. It
talks specifically to the quenching process. The book is no longer
in print, but it is sometimes available on-line. You might check it
out at your local library also. It will answer a lot of questions
on hardening and a lot of the translates to the problems
we work with and around as gold and silver smiths.
Don Rogers
Kate -
My toolmaking instructor used transmission oil to quench after
tempering.
Debby Hoffmaster