An older perspective on heat treating...

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Sword and Shield

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Courtesy of the "Dr. Chase's Recipes or Information For Everybody- Enlarged and Improved Edition" copyright 1903, comes this old method for heat-treating and tempering a blade.

In forging out the knife as you get it near to its proper thickness, be very careful not to heat it too high, and to water-hammer as for mill picks; when about to temper, heat only to a cherry red and hold it in such a way that you can hold it plumb as you put it in the water which prevents it from springing-- put it plumb in the water and it will come out straight.

Take it from the water to the fire and pass it through the blaze until a little hot; then rub a candle over it on both sides and back to the fire, passing it backward and forward, in the blaze, turning it over often to keep the heat even over the whole surface, until the tallow passes off as though it went into the steel; then take out and rub the candle over it again (on both sides) each time and back to the fire, passing it as before, until it starts into a blaze, with a snap, being careful that the heat is even over the whole length and width of the tool, then rub the tallow over it again and back, for 3 times, quickly as it burns off; and lastly rub the tallow over it again and push it into the dust of the forge, letting it remain until cold.

If these directions are followed with dexterity you will have the temper alike from edge to back; and the edge will be the best you ever saw, as Davy Crockett used to say "It will jump higher, dive deeper, shave more hogs, bend further without breaking, and give more satisfaction than all other knives put together."
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Dr. Chase also gives a brine quench formula, obtained for ten dollars from an English miller- 1/2 teacup of salt, 1/2 ounce of saltpeter, 1 teaspoon of alum and one gallon of soft water.

Looking at the brine for starters, this sounds pretty close to a good brine quench. His HT/tempering technique sounds equally sound, however I question the use of wax. Wax melts at about 150F, which is miles below even a base temper. What's the purpose of it?

Just thought a historical perspective may be worth some discussion. :)
 
That's pretty darn cool! I wonder if alum or saltpeter increase the surface tension of water like modern surfactants (Jet-Dri, etc...)?
 
The burning wax trick is similar to the burning oil trick. It will heat the blade enough to temper it as it burns off, but (hopefully) not enough to over temper it. The flame is not very hot (as flame goes).

Bill Moran was contracted to make a batch of springs in his early days. He took the order, but had no idea how to make a spring.Making them, and hardening them, was easy.Tempering ( he would pass the springs back and forth over the forge to heat it up to what he thought was enough. He got them hard,but was having a problem with them breaking.He would heat the steel over the coals until he thought it was hot enough ,and stick it in ashes to cool. If he heated them more the temper was ruined, and the springs wouldn't hold pressure. He asked around and an old blacksmith told him how to do it. These are Bill's words, as close as I can remember them:
"Take a baking sheet (rectangular pizza pan) and put about 1/8" of kerosene in it. Place the springs in the oil and coat them with it. Place the sheet on the coals and step back.Allow it to heat until it bursts afire. Remove the pan and set on the anvil until all the kerosene is burned away. The springs will have a perfect temper." Bill said some of those springs he made ( I think they were for the RR company) were still in use 20 years later.
Stacy
 
Sword and Shield said:
Courtesy of the "Dr. Chase's Recipes or Information For Everybody- Enlarged and Improved Edition" copyright 1903, comes this old method for heat-treating and tempering a blade.



Dr. Chase also gives a brine quench formula, obtained for ten dollars from an English miller- 1/2 teacup of salt, 1/2 ounce of saltpeter, 1 teaspoon of alum and one gallon of soft water.

Looking at the brine for starters, this sounds pretty close to a good brine quench. His HT/tempering technique sounds equally sound, however I question the use of wax. Wax melts at about 150F, which is miles below even a base temper. What's the purpose of it?

Just thought a historical perspective may be worth some discussion. :)
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The guy states the use of a candle, but talks about tallow, not wax.
Tallow is animal fat, used to make older, very cheap candles which gave off poor lighting.
There are then 3 types of wax, with different melting points:
paraffin is available in low, medium and high grade (based on melting point) and melts at 130, 145 and 150-160 °F
Beeswax melts around 150 °F
Stearin melts aroun 136 °F

It's worth noting that the guy talks about heating the steel until the wax flashes and disappears from it completely.
Which is much higher temperature than melting point.

I'd also add that a spring temper is good for some knives, but far too soft for others.
 
How hard is the spring temper? Most springs I know would be in the low 50s at most, which wouldn't make a good knife even by 1903 standards.
 
Yes, around 50.
Good for some swords, but not for knives, even if I don't know what were the standards in 1903.
Perhaps there wasn't any good method of producing decent fillet knives without giving them a spring temper.
Anyway, I think the whole "trick of the trade" of the whole proceeding is to be found HERE:

If these directions are followed with dexterity you will have the temper
Click to expand...

That is, in the end there's no magic recipe: a skilled craftsman will make a good knife, an unskilled one won't, if not by accident, no matter what.
 
Mark Williams said:
The flame is not very hot (as flame goes)

Do what? :D
Click to expand...

Not all flame is the same temperature. If memory serves me, a mixture of oxygen and acetylene can burn at 6,000 degrees.

Though obviously, if you can see it, it is emitting visible light meaning it is over 1000 deg.
 
Actually, there are flames that burn so low that you can let a small quantity of liquid burn on the palm of your hand (around 80 °C).
It's called "cold fire" and is used for special effects in movies. It requires protective clothing, though.
Anyway, not all stuff burns the same temp.
Aluminum and iron shavings, ignited by phosphorus, burn well over 5000 °C. It's called "thermite" and can burn thru almost anything.
 
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