Narex Chisels and Gouges are hardened using an Iso-thermal process.
When Steel tools are made the high temperatures used, 750-1200 deg C, change the crystalline structure of the steel and it’s absorption of carbon. If this steel is then quenched, the rapid fall in temperature solidifies this crystal structure resulting in highly brittle but very hard steel. In order for this steel to be used in tool making the hardness must be tempered by re-heating, then gradually cooling the steel so that a change in the crystal structure occurs.
Cheap tools are tempered by repeatedly re-heating and cooling the steel in oil or water baths. The crystal structure of the steel remains variable and weak spots can occur.
Narex use a process called Isothermal Hardening. This involves a single operation where the steel is cooled in a bath of molton salt at 200 deg C. Holding the steel at this temperature allows the crystal structure to change throughout the steel and accurately controls the hardness. The result is a tool that has the best balance between hardness and strength.
Narex Chisels and gouges will hold a sharp edge for much longer than standard tools.
Careful storage and a wipe down of your Narex Chisels and Carving Tools with a light non-hardening oil after use will keep your chisels in good condition. An unusual characteristic of Cr-Mn steel is that it cannot be etched, so the blades must be printed instead, contact with solvents or abrasion may therefore remove the markings on the blade. Narex chisels are ground before being hardened, so you may find that edge retention improves significantly after the first couple of honings, this is completely normal and once the first couple of millimetres have been sharpened away you will begin to experience what a pleasure Cr-Mn steel is to use.