Bringing Out the Temper Line

[Andrew Lynch]

I've heard that if you sand the surface of a blade that shows a temper line (in order to change the blade finish, for example), the temper line will disappear (visually). Is this true?

If so, how can I bring the temper line out again? I heard that an acid etch might work, if so, where can I buy the stuff needed to do that, and perhaps instructions on how to do it?

Thanks!

 

[Robert Marotz]

Conventional dry sanding of a blade's surface acts to burnish the surface of the steel, which can obscure the temper line.

Common ways of bringing it up are through more labor-intensive polishing and an acid etch.

There's a variety of ways to etch, you could use vinegar, or you could use ferric chloride diluted in water. They're not extremely difficult to obtain (grocery store or radio shack), and can work well. Be minded however that etching discolors the rest of the steel too, and should be at least "touched up" after the etch. If you want to go for visibility, having a dark line is fine and works well.

 

[blackboogers]

My own findings are that 1 part vineger to 4 water works best for carbon steels. I nuke the mixture in the microwave until steaming hot and put your blade in. The etch will take place very quickly but do it only 1 to 3 times or the steel gets very grainy looking,you will want to polish with some fine micron paper in between dips. This method works extremely well with 1095. I like the ferric with damascus.