Jump to content
Buck Hedges

Is This Dark Straw Color?

Recommended Posts

I hardened a ball-peen 'hawk and my karambit last week, quenched in peanut oil, and then baked at 400 degrees for 2 hours. When they came out, they looked like this:

 

 

 

 

20161214_152115_zpscvijndzt.jpg

 

 

Is this the dark straw color we're trying to achieve?

 

If so, it's the high point of my week!

 

Share this post


Link to post
Share on other sites

Looks like a mix of dark straw, light straw, and a bit of brown and purple, but yep, that's pretty much what to shoot for visually. How does it feel on a file, and have you tried the brass rod test? Bending test?

Share this post


Link to post
Share on other sites

The file skated across it.

 

I don't know what the brass rod test is.

 

It's made from a horseshoeing rasp, so as for bending it...

 

I'm afraid to try.

 

The tomahawk I hardened with it is REALLY hard. I have one part of the edge I want to thin down. It's not cooperating.

Share this post


Link to post
Share on other sites

Ooh, yeah, don't try to bend it, then! You may want to hit it again at 425, ideally a file should barely bite. The brass rod test is pressing the sharpened edge sideways on a brass rod. The edge should be able to flex a tiny bit without chipping, cracking, or bending permanently.

 

And on hawks you want it softer, more like 575 degrees. I prefer axe-like thngs to dent instead of shatter if you hit a nail or something.

Share this post


Link to post
Share on other sites

Well, as the stove is already heat-treating another knife (just a RR spike and not worth any other details), I think I'll throw it in when the first one comes out.

 

Thanks for the advice. I'll remember the temperatures next time around!

Share this post


Link to post
Share on other sites

My advice is to go by temperature instead of patina. Temperature in a regulated oven is consistent whereas patina can be influenced by a number of factors and can be unreliable.

 

Doug

  • Like 1

Share this post


Link to post
Share on other sites

I don't have a way to check the temperature, other than how hot the stove tells me it is, so for now, I go by color.

 

Just for kicks, I threw it in for another hour at 425. It came out looking like this:

 

20161221_153543_zpsjr2q61yw.jpg

 

Too much?

 

Ironically enough, when it's done, this knife will be blued, and will I'm using blue plastic impregnated paper in the handle, and it will be called, "Blue," after the raptor in Jurassic Park IV, since it's all talon-pointed and toe-claw shaped..

Share this post


Link to post
Share on other sites

Get an oven thermometer at the local grocery store and put it on the rack by your blade. That will tell you the temperature of your oven well enough. You don't need a pyrometer.

 

Doug

Share this post


Link to post
Share on other sites

Well, the oven does have the temperature indicator at the top, and it's digital, so I assume (with all associated irony and sarcasm) that it's right. On the other hand...I assume it's right. May have to hit the 'ol supermarket tomorrow.

Share this post


Link to post
Share on other sites

i have two oven thermometers in my quick temper oven i average them out to get close to the temp im getting then kiln them the next day after its cool from heat treat

Share this post


Link to post
Share on other sites

The trouble with kitchen ovens is that they tend to cycle over a wide range of temperature. Mine, for instance, clicks on at 50 degrees below target and off at 50 degrees above target, but it's old. A pan of sand to bury the blade in atop a couple of foil-wrapped bricks to keep the oven clean helps stabilize the temperature, but an independent thermometer is a must.

 

Oil on the blade will skew the colors as well. A blade that shows bright blue with a little oil on it may be dark straw if clean.

Share this post


Link to post
Share on other sites

I completely ignore the oxide colors, they can be very misleading. Doug is right, spend the money (most are under $10) and get a good oven thermometer...Alan's suggestion of adding thermal mass is a good one.

 

Tempering is such a crucial step, yet so simple... There's no excuse not to do it right.

Share this post


Link to post
Share on other sites

As said already.

The colours can easily be misleading.
Any oil or fat on the surface will throw the colour.
Repeating the tempering without removing the previous colour will produce a darker hue.

To get anywhere close to readable colour, the surface must be freshly cleaned with abrasives and double checked to make sure it is fat free.

A good method for tempering is to use a hot oil bath. Use a frying thermometer and a large enough pan for your blades. With knives this is not problematic. For sword blades you have to get a bit creative.
Treat the hot oil with some care and caution as the situation quickly can turn pretty intense.

:-)

Share this post


Link to post
Share on other sites

The trouble with kitchen ovens is that they tend to cycle over a wide range of temperature. Mine, for instance, clicks on at 50 degrees below target and off at 50 degrees above target, but it's old. A pan of sand to bury the blade in atop a couple of foil-wrapped bricks to keep the oven clean helps stabilize the temperature, but an independent thermometer is a must.

 

Oil on the blade will skew the colors as well. A blade that shows bright blue with a little oil on it may be dark straw if clean.

I have bricks. I have a pan. Sand I can get (Which will give my family a reason to go to the beach this summer!). I'll try it.

 

I completely ignore the oxide colors, they can be very misleading. Doug is right, spend the money (most are under $10) and get a good oven thermometer...Alan's suggestion of adding thermal mass is a good one.

 

Tempering is such a crucial step, yet so simple... There's no excuse not to do it right.

 

I actually did learn that with my last batch of blades. I had left the peanut oil I quenched them in on, to prevent rust. Beautiful metallic blue color. Next time I'm shopping I'm going to raid the dollar store for a thermometer. My wife may actually have one stashed somewhere, too.

Share this post


Link to post
Share on other sites

Ooh, baked beach sand ought to smell, well...interesting. :lol:

Share this post


Link to post
Share on other sites

Ooh, baked beach sand ought to smell, well...interesting. :lol:

Sounds fishy, if you ask me!

 

I could not resist.

Share this post


Link to post
Share on other sites

Ooh, baked beach sand ought to smell, well...interesting. :lol:

 

Sounds fishy, if you ask me!

 

I could not resist.

 

Back in my college days, I had a side business making "wargames terrain," miniature terrain for tabletop wargames. One of the things I used was sand scrounged from the piles left behind on the streets every spring. After a few...odiferous results...I learned to dry it first, and sift it, to get rid of as much not-sand as I could. All it really took was some spread out newspaper, a thin layer of sand, and leaving it sit for awhile. I also learned just to take the loose sand from the top of the pile, because it was mostly sand, drier, and Sylvester and Tom hadn't visited it to deposit Tweety and Jerry's...remains.

 

The particular beach I'd visit is the North end of Bear Lake, Idaho. It's not Waikiki by any means, but the sand is fine, the water is only waist deep for a quarter of a mile out, and for Idaho, it's warm. Meaning non-frozen. But I don't want to wait that long.

 

This round, though, I'd planned on either waiting til summer, or just picking up a bag from Lowe's.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...