Heat Treat With Borax

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peter nap

peter nap

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Nov 27, 1999
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The Herring aren't running real well yet so I decided to try something different today. I wanted to see if I could cut down on the amount of scale on my 5160 knives when I heat treated.

I took one of the ugly blades I forged and ground and warmed it in the forge. I dunked it in Borax just like I was going to weld. Just to see what was going to happen I overheated a lot and left it in much longer than I would for heat treating.

I pulled it out and quenched in water. I couldn't believe it. It didn't break. I cleaned it off with a quick pass on the wire wheel. No scale, no pitting.....I repeaated it this time quenched in motor oil. Same result. One more time in crisco. Same thing.

All three were hard. File just skated off. I tempered them and made two passes on the grinder. Not a pit to be found, just bright smooth metal.

I'm not sure what this proves but I'm going to try a blade to finish and see if it really saves time.

I also want to see what it does with oil quenched 440C. I don't have any right now but as soon as I make some more Christmas tree do-dads, I'll try it!:D
 
Hey Peter,

I used to boil water and borax and dip my blades in it and let dry before heat treating, but found it a lot easier and better to leave quite a bit over sized, then heat treat, then grind to finished shape with a new 50 grit belt and then go straight to a new 400 grit, just like steve johnson does it, I stop there and go to hand sanding because I'm doing mostly flat grinds off a platen, but if your doing hollow grinds off a softer wheel, he says you can take them to a mirror finish with just a couple of cork belts and the buffer. His tutorial is on CKD, several say it works great.

Bill
 
It acts as a flux and seals the steel from oxygen. This prevents scale from forming between the layers.
 
Peter,

I was going to use Borax as well, but got confused with the step process. My understanding was to heat the blade to a dull red, then dip or sprinkle on borax. Replace the blade in the forge/oven and take to non-magnetic, then quench in oil, temper, and then boil in water to remove borax. Sounds like you've eliminated a lot of steps I would have taken. You've indicated you took to non-magnetic and then quenched in water? No need for oil quench after that? Proceed with tempering in oven as usual? I normally use 01 and use a Wayne Goddard "goop quench". Now I'm confused. If you use borax, run to non-magnetic, quench in water (?) to remove borax (does the quench in water take the place of the quench in oil?). I'm confused with exactly when to remove the borax and what type of quench (now to use)-any help out there?-thanks, Dan
 
Stop Tangus!!!!! Don't let me teach you bad habits. I was playing and water quenched for the He!! of it. I was just amazed that it didn't break. I don't know if the Borax had anything to do with it or I just lucked out but it's not a good idea with 5160 or anything other than water quench steel. Even then it should be quenched in brine.

I played with it a little more yesterday since the fish weren't biteing again. What I did was normalize three times and on the first cycle, dipped in Borax. I then brought it to non-magnetic and quenched in Crisco. Still no scale. I had ground this a little closer than I generally do because I didn't have the scale to deal with. I triple tempered it with the borax still on and used a wire wheel to clean the bulk of it off. This kept it from clogging my belt. I finished the grind and the Borax went away in the process.

As far as I can see the real benefit is that It can be ground a little closer prior to heat treating. As Bill pointed out there is no benefit at all if you allow a lot of extra steel for finish grinding. I have always been concerned about overheating the blade while doing the finish so this does allow me to do more grinding prior to HT'ing.
It may also provide some protection against burning the carbon from the steel surface during the normalize and HT session. I haven't done near enough experimenting to make that assumption yet. Right now it's an idea to work with. Nothing more so consider the source and be cautious about using the process on your good blades.:confused:
 
thanks Peter, your second paragraph clarified a big mystery for me.( I thought you had discovered the "holy grail"! I wasn't sure you ran the borax through all the steps before removal. You've clarified precisely. I've used the borax through the entire process but wasn't sure it was the correct method. I did some HT this past Saturday (couldn't get away with it on Easter) and I did notice that the borax on the blade and ricasso didn't have scale, but the unprotected porton of the tang did have. I tried an experiment with boiling the blades in water to dissolve the borax. worked partially. I just moved to a scotch-brite belt and knocked it off. again, thanks for the info supplied--Dan
 
I see in my new sale cataloge from Enco they offer what they call 'Stainless Steel Tool Wrap'. They claim it is good to 2000 deg. F. and creates an air tight seal for heat treating. Part# 406-0110 is 24 X 50 (89 bucks), # 406-0112 is 24 X 100 (155 bucks). It is of 321 stainless and is .002 thick. The cataloge catagory is 'Raw Materials'. I have not tried to look it up on their site but am sure it is there.

Enco: www.use-enco.com
(800)873-3626

I have been buying tooling from them lately and have been happy. They get things in the mail fast and even do C.O.D. company check.
 
Stainless steel foil is SOP for heat treating High alloy steels however some of the more open minded folks here have found ways around it. The real problem with it is the cost. For the full timers, they are making little enough due to the time involved in making knives and for people like myself.....well, I like finding ways to be less reliant on disposables. Belts cost enough when you don't derive income from selling the knives, propane costs and steel that I haven't scrounged costs.

Besides, I enjoy experimenting. If none of us ever tried new methods the industry would not grow at all. I may never find the formula for the perfect cutting blade but I'm sure having fun trying.
 
Doc, you can do it either way. If you heat the blade I just stick it in the box. To mix with water I make it like thick gravey!
 
Interesting sounds like you've replaced the need for s/s wrap.
with the wrap your creating an atmosphere the same as the steel
even if you use the wrap if it's got air
in inside you can get scale,
so you have to get it tight,some guys use a trick with the old wrap
to double wrap.
the place I was a tool a die maker in years ago had a heat treating oven
 that was called an atmospheric generator oven you got no scale all it,
  I believe was done by
 recycling the burnt propane ( use to heat it with) back into the oven.
 thus atmospherizing it.
if I'm wrong here please corect me..
 
I remember about 20 years ago a fellow telling me about a PBS show he had seen that tryed to describe the way the Japanese sword makers made them. The one thing I remember well is that they supposedly coated the blades with clay and that for tempering they used different types of clay on different parts of the blade. He described to me that the clay isolated the blade from the atmosphere, for hardening, and that some clays would insulate the blade from heat better than other types of clay (the advantage of using it for tempering).

I wonder what knife makers on this forum have experienced in using clay in heat treating(???). Does this make any sense or did I remember hearing this story wrong?
 
Hi Roger
It's been said here many times.
  what I know about it is it's,,
clay and rice ash.
put on in different thickness.
thicker where you want it soft and thin
where you want it hard and to make the Harmon
design.. well this is just the short of it anyway..
 now we're going to get into water quenching again..
that was done just a short time ago too.
 
I started a thread a couple of weeks ago on KFs Newbies forums about clay tempering. My first attempt cracked miserably. It was my error on not preheating my water and moving the blade around in the quench tank.
Second attempt came out pretty nice with a good hammon line.
I'm using 2000 degree fireplace refractory caulk for my clay.

Doc
 
Just to bring whoever is interested, up to date. I did a full blown blade today with the Borax suspended in water and brushed on between cycles. I ground the blade very thin, 1/32 of final grind. I didn't get any distortion in the edge or scaling or blistering. It's in the freezer now but I suspect it will save me 30 minutes of grinding time after tempering. One interesting note: when I edge quenched I could hear and see the Borax pop off. I thought I cracked the blade on the first quench but it was just poping off due to the changes in the steel.
 
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