How did they Temper 150 years ago?

D

David LaFerney

Joined
Feb 4, 2015
Messages
122
Smiths, not industry. If you didn't have a temp controled oven or a gas torch how would you go about doing a controled temper? Zen like skill - or something else? Boil in oil maybe? I know that ovens existed, but what did a common village Smith have to work with? Or did they actually use something like a masonery oven?
 
Interesting question! And back in the day before metallurgy was a science how did they even know to stick the steel back in the heat to temper it? Somebody was a good observer I suspect.
 
They would typically take a brush to the knife and remove the scale so they could see the steel. Then they would take a hot iron to the back of the knife and watch the colors as the hot metal oxidized. They could do an edge quench and watch the colors as the heat from the back of the blade tempered the edge.
 
I have heard that Japanese smiths used WATER to judge tempering temperature. The blade would be brought up to heat, and the smith would let a few drops of water fall onto the hot blade. Depending on how the water reacted, they could tell approx what temperature they were at. Apparently water dances and bounces around very differently at a given heat, and these smiths were able to learn how water "danced" at what temp. I think that is way cool. Maybe not super accurate, but super cool.
 
Dancing water drops ? That's how I tell if a frying pan is up to heat !!
Tempering was done by watching 'temper colors' That's how we have a temper color chart .There are also tempering sticks . crayons that melt at specific colors and temperatures !
Remember that temper colors are colors of oxides on the surface .This is influenced by temperature ,surface condition [ oil , dirt , etc.].The color indications are no too bad if you use the same lighting etc. Simple carbon steels work better .Complex steels are not for color indicators as various things are happening and take time .Our normal knife steels require 1, 2, or 3 tempers of 2 hours, coolin g in between.
 
western smiths used the oxide colours because they tended to harden the whole blade and needed a fair amount of temper, japanese smiths used differential hardening and were able to leave their cutting edges much harder because the tougher body of the blade supported them...but the problem is oxide colours don't kick in until 3 or 4 hundred degrees...so the water method is generally used for the stages just below the faintest straw yellow oxide...
 
You must log in or register to reply here.
Back
Top