I recently watched Tai Goo harden a blade on the Hoods Woods video and he said you should harden or quench the blade while its pointing north. The reason for this is so the blade will not warp while cooling. The blade is not magnetic when it is a very hot temperature, and when it cools all the particles line up and point magnetic north. It makes sense but is it really true? A friend of mine questions it but I beleive it so what is it, is it true or not? Please help me out here. Thanks.