The new Clifton cryogenically treated plane irons are laser cut from hot rolled O1 carbon steel plate. The red hot steel is passed through a series of rollers that progressively forge the steel whilst gradually reducing its thickness. If you have ever seen railway line or armour plate being roll forged, the process is very similar. After cutting, the blades are normalised to refine the steel's microstructure and then reheated and quenched in liquid nitrogen.
The effect of Cryo treatment on plain carbon steels is not as pronounced as it is on air hardening steels like A2 or D2, but the result is a hard, strong, stable blade that retains the characteristic stone feel and fine edge taking qualities of Sheffield carbon steel.
From a user perspective, one of the main benefits of the new process is that the bevel side can be determined after heat treatment (with a hot struck blade the face side is determined at the forging stage). This means that the flat side of the blade is now always substantially flat with a slight tolerance for beneficial concavity.
In short, the mouth-watering sharpness and pleasant honing characteristics of the original hand forged Clifton irons are retained, but they are easier to prepare, a smidgen harder and have fractionally better wear resistance.
If you are retrofitting a Clifton iron to an old Stanley or Record plane, please check that you have at least 4mm of Y lever tab protruding above the surface of the frog.
- Fits: No.4½, No.5½, No.6 and No.7 bench planes
- Width: 55mm (2⅜")
- Thickness: 3mm (⅛")
- Made in Sheffield