Hey All-

I know this has been discussed in forums, but at the moment I can't seem to find any stored info.

Ed, I emailed Tom about possibly differentialy heat-treating a dagger blade out of 1084, or maybe 5160. For now, with my lack of forging skills, I'd cut and grind it. Maybe forge the blade width out and the tip a little, but I couldn't forge the bevels yet.

Anyway, I read somewhere that you can paint the blade with some sort of chimney sealer, then go about normal heat-treating and get a nice temper line, since the sealer blocks off so much heat to where it's painted on...

What do you think???

Thanks,
Nick

ps- I've emailed you about coming over, but I don't know if my email account is working...any chance you got an email from me Ed? thanks!

There's a couple of techniques that work. One is to coat the blade with a refractory paste (available at most places that sell wood stove or fire place supplies)--about 1/4" inch thick in the center of the blade tapering down to very thin to none on the cutting edge--then heating and quenching. Rob Hudson, told me about a product called Satanite. He made a runny slurry of the stuff and painted the whole blade with a light coat. After drying, he coated the spine (in your case the center ridge) with a 1/4" thick coat tapering down to nothing on the cutting edge. Then he heated his oil to somewhere around 400+ degrees, heated the blade to where the edges were at critical temp (no longer magnetic) then quenched it in the hot oil--there by quenching and tempering in one move. I've not tried this, but Rob Hudson is no light weight, and I'd take his word on it. He wrote an article for Blade magazine several years ago on this--the article is about achieving good temper lines, but the same would apply for hardening or tempering daggers.

Another thing you can do is to heat and quench the blade as you normally would. After it has cooled, clean it to bright steel. Using a small nozzle propane or MAPP gas torch and keeping the flame in the center of the blade--"paint" the flame back and forth until the edges turn a golden brown (straw color) and the center ridge is a bright blue. A heat sink paste such as Anti-heat or Block-it paste applied to the edges can help, if you have problems with the colors running too fast. Keep a bucket of water handy for quick quenches if the blue starts to travel to the edges begin to darken beyond the straw stage--like to brown or purple. Until you get a feel for it, be prepared to move quickly, otherwise you will need to re-quench your blade. If you're new to this, all I can say is do it a lot. At first it can be the most friustrating thing under the sun, but you will, with enough practice, get the "feel" for it.

One more way is to heat a piece if 1/4"--3/8" round stock (can be mild steel) red hot and hold it (with vise grips or secure tongs :) ) against the center ridge of your dagger until the colors (blue on the center ridge and straw on the edges) start to run.

Good luck with this, Nick. Not knowing you or your skill level, I added a lot of "basics," like defining critical temp, and talking about the colors evident during tempering, etc. I didn't mean to imply that you may not already know some of the things I wrote above, but, just in case you didn't, I figured better safe than sorry. Also a lot of new knifemakers read these posts and the extra info might help answer some questions for them.

Hi Nick!
Maybe not as accurate, but a very simple way to differentially heat treat a dagger is to heat it in the forge to the point where only the two edges reach critical (the edges will of course heat more quickly due to the thin cross section, and the center ridge, due to it's mass, will not reach critcal by the time the edges are there) Then using a quench tank that will handle the job, quickly place the dagger, point down, all the way into the oil, doing your best to not swish it around. I have done this many times, and once finished and etched, you will achieve a very nice temper line. This method is not nearly as exact as the clay/coating method, but then again I have never figured out too many uses for a dagger outside of a stabbing type weapon.

Thanks for the replies guys.

I do understand all of the terminology, and have seen most of the heat-treating processes done...but don't have too much experience doing it myself yet as I've been a stock removal maker since I started (until recently).

You're right Ed, they're just pointy...but for some reason I like making them. I just thought a dagger with hamon lines would be cool.

Tom, Bill, and I are, hopefully, getting together this week-end and we'll get something figured out.

To get the temper line to really come out, what kind of acid etch am I looking at? Ferric chloride? for how long? at what point in the finishing process? It seems like most guys take blades like this to about 600x.

That one Terry Primos poster in the Display Case is awesome!

Thanks again!
Nick

For a dagger, getting a good hamon using the clay-resist method is difficult if the blade is thin. What works really well is using the above mentioned technique of allowing just the edges to reach critical combined with a clay coat.

Coat the ridge of the blade with around 1/8" of your clay (I swear by Parks Furnace Cement rated for 3000 degrees and available from www.mcmaster.com). Slowly bring the whole blade up to around 1000 degrees and then tweak your gas to bring the edges up to temp quickly. A vertical quench is definitely going to be the way to go.

If you're using a deep hardening steel like o-1 or 5160 or 1084 (strange stuff in that regard), you almost have to use the above method. If you have a shallow hardening steel like 1050-1080, the clay-resist method will work.

The clay doesn't work by insulating the steel, which is why it works poorly with deep hardening steels (with the exception of a thick coat on a single edged blade), rather the clay works because it keeps the water off of the blade long enough to get it under the nose of the curve (about one second with the 10xx steels). You can add lime or ash or powdered fire-brick to the clay to make it insulate a little, but this is really more a control of the body of the blade as opposed to the hardened edge (ie., you'll have more martensite mixed in with the pearlite in the body if you use the more insulating clay). It takes about 1 second to get your steel below 900 degrees F in a waterquench, longer for oil. Go with water if you have good control over your temperatures (like a salt-bath), go with oil if you're eyeballing it.

Joe,
I've been impressed with the replies you've given on various forums around here lately. It's been obvious from your responses that you have more than just a little experience in the fascinating world of bladesmithing. :)

We need to get you registered and logged in so that you will have the full benefit of the forums.

Registering and logging in will change your status from "Unregistered User" to "CKD Elite Member", will start off your post count, and will allow you to edit your posts. If you have your email address in your registered profile, you will also be able to receive the CKD Newsletter.

Umm, out of curiosity, you wouldn't happen to be from Arkansas would you?