Many  woodworkers like to make their own tools and some do their own heat treating. Being able to tell which steel is which is a big help when it comes time to heat treat, quench, and  tempering any steel

Spark testing steel  on any grinding wheel can tell you what type of steel you have and if it is one of the tool steels, you can determine  which one it is by the sparks alone.

 

This is so because the alloys in metals give off different spark colors ad well as spark patterns.  This is  one of the things that makers of fireworks  rely on.

 

Simply bring the metal to bear against the wheel and observe the carrier line of sparks that fly.   It helps to dim the lights.  

More carbon = brighter sparks with more  branching spark trails

More manganese  =  right angle  branching

More Tungsten = broken patterns

 Each alloying element produces a unique spark pattern and once you get to know them they are remarkably distinctive one from another.

Cast iron gives a dull red carrier line with no secondary bursts of white hot sparks

Wrought iron is a little brighter and may show traces of carbon.

Mild Steel has branching hot sparks from the carbon

O1 has lots of carbon and thusly a very exciting carrier trail with lots of branchings each with hot white sparks   that fan out at angles from the carrier trail of around 30 - 60 degrees 

High-speed tool steel shows occasional carbon sparks but theother alloying elements  most of which are not carbon, give off an orangey color  and  the sparks show at different levels of brightness and are some what broken  up.

Manganese steel gives off spark branchings that travel at right angles to the carrier trail.

 Air hardening steel shows some manganese spark branchings  but the tungsten  breaks it all up making the patterns irregular

 

 If you know the elements in the metal you can use them to learn the different spark patterns and colors.  Once you learn them you will always be able to tell which steel is which by taking it to the  grinder.

 

 

 

Really Neat! Thanks for the post!

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Lew Kauffman-
Wood Turners Forum Host

Time traveler. Purveyor of the world's finest custom rolling pins!

Cliff as usual, a very useful and wonderfully informative post. I am going to print out the trail descriptions and pin it above my grinder and try to learn it when I am at the grinder.

Personally, I love sparks!!!! I remember as kid burning through some scrap metal at my dads grinder just to see sparks. Wouldn't do that today however, but it was fun!

Thanks again Cliff!

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John Morris
The Patriot Woodworker
Proud Supporter of Wounded Warrior Project and Homes For Our Troops