Ok...
so maybe heating the blades up isn't necessary - they've already been tempered, so I wouldn't want to untemper them.

I'm not sure about how much carbon is left unbonded, but why do you think cryogenically lowering the temperature to -300 improves car parts, gillette DE blades and cartridge razors, but wouldn't improve straight razors?


FYI:
http://en.wikipedia.org/wiki/Carbon_steel
Silver Steel or high-carbon bright steel, gets its name from its appearance, due to the high carbon content. It is a very-high carbon steel, or can be thought of as some of the best high-carbon steel. It is defined under the steel specification standards BS-1407. It is a 1% carbon tool steel which can be ground to close tolerances. Usually the range of carbon is minimum 1.10% but as high as 1.20%. It also contains trace elements of 0.35% Mn (range 0.30%-0.40%), 0.40% Cr (range 0.4%-0.5%), 0.30% Si (range 0.1%-0.3%), and also sometimes sulfur (max 0.035%) and phosphorus (max 0.035%). Silver steel is sometimes used for making straight razors, due to its ability to produce and hold a micro-fine edge, as those made by the French company Thiers-Issard.

http://en.wikipedia.org/wiki/Cryogenic_tempering
Cryogenic hardening is a heat treatment in which the material is cooled to cryogenic temperatures to the order of -185 °C, usually using liquid nitrogen. It can have a profound effect on the mechanical properties of certain steels, provided their composition and prior heat treatment are such that they retain some austenite at room temperature. It is designed to increase the amount of martensite in the steel's crystal structure, increasing its strength and hardness, sometimes at the cost of toughness. Presently this treatment is being practiced over tool steels, high-carbon, and high-chromium steels to obtain excellent wear resistance.

http://en.wikipedia.org/wiki/Cryogenic_processor
Before computers were added to control cryogenic processors, the "treatment" process of an object was previously done manually by immersing the object in liquid nitrogen. This normally caused thermal shock to occur within an object, resulting in cracks to the structure. Modern cryogenic processors measure changes in temperature down to fractions of a degree and adjust the input of liquid nitrogen accordingly to ensure that only small fractional changes in temperature occur over a long period of time. The general processing cycle for modern cryogenic processors occurs within a three day time window, with 24 hours to reach the optimal bottom temperature for a product, 24 hours to hold at the bottom temperature, and 24 hours to return to room temperature.