Hi All

This may be of more interest to the hard core iron pounders out there...although you may know all about it, it is an oldie after all!

I was looking through "Dr Chase's Receipt Book" 1885ish and came across this recipe;

Steel -To Temper Very Hard
Take water, 2 measures -no matter what size - wheat flour, 1/2 measure, and 1 of common salt.

Directions
Mix into a paste; heat the steel to be hardened enough to coat with the paste - by immersing it in the composition- after which heat to a cherry red and plunge it in cold soft water.
If properly done, the steel will come out with a beautiful white surface, and very hard.

Remarks
It is said that this is the process in which Stubbs' files are tempered.

So is anyone game enough to try it out? Or know whats going on with this?

Cheers

Boyd

It sounds like carburization. Same as Teophilus' greased files.

Hardtack for lunch again... I'll have to try this one of these days.

How would this actually work?
Would the carbon to harden the surface come from the salt, held in place with the flour and water?
C

The Carbon would come from the flour.
The exact role of the salt is unclear to me, brine is sometimes used as a cooling medium (as is oil) Brine transports heat differently than pure water. It is supposed to have something to do with how watervapor is formed (or not) on the surface of the heated material when submerged.

Adding the salt to the paste might just be a way of getting the same effect when cooled in pure water.

Hi guys

My guess is the paste is more to dampen scale development. To carbonize the material it would need to be held at temp for a long time. The salt would help with the quench as it counters a steam envelope developing around the blade. Soft water could have salt in it. That, I believe, is what a water softener is designed to do add salt to water.

So the result is a system designed to reduce scale, pretty important in making a file, and using the right kind of water.

Best
Craig

According to my blacksmithing teacher, mixing salt into the quenching process does produce a very hard steel. I forget exactly why, though.

Salt water has higher density than fresh water. Objects that are just heavy enough to sink in fresh water will often float in salt water. All else being equal, greater density=greater heat absorbtion/transfer capability.

What the salt does is inhibits the formation of steam around the blade. Steam is a good insulator. When you plunge red hot steel into water it can actually form an envelope of steam which slows the quench. If the water is moving or agitated or has particulate mater of some form in it tis is reduced. That is why they had recipes for different hardnesses in the period discussions of this. They thought the different additives imparted attributes to the steel. What was actually occurring is they where regulating the speed of the quench. One of the draw backs to empirical systems, if you attribute the cause to the wrong affect it looks like it is working but it may happen for a completely different reason.

Best
Craig

So the paste stops scale, the salt stops steam bubbles, and the wheat could add some carbon. Interesting.

I like Craig's answer better than mine ;)

While we're on the subject...what about rubbing a ram's horn on the steel?

I was watching TV Espanola and there was a smith that was making an axe head and he rubbed a ram's horn on just inside of the edge before putting back in the forge. he then quenched it in what looked like a natural spring inside his shop.

I missed what he said it did but all of his other explanations seemed right on.

Nice answer Craig.

Cheers

Boyd