Hi, I'v been in bladesmithing for about 20 years (started at 14) and I thought once and a while I'd share a few things I'v picked up over the years. Here's one. In my early 20's I got in contact with a master bladesmith of the Japanese forms (who wished to remain nameless). He was very open about teaching the "secrets" he knew. I learned a foolproof way of how to edge harden blades. It works best on simple carbon steels and even will harden mid to low carbon steel, does not need to be folded or laminated steel. The blade should be made strait and at cooling it will curve by itself. First, the clay, it is a mix of half red clay, half fine sand, and 1/20th ash. Mix until the consistency of cake frosting, (Mmm frosting) than coat the entire blade with a layer 1/4in thick. Then remove with your thumb the clay mix from alone the edge, making a wave pattern along the edge. Round off clay edges with your hand. Let dry for a week. Next heating and the cooling the blade. The cooling mix, add salt to warm water until a hardboiled egg will float in it.(remove the egg)The blade will be heated to a orange color, than held over the warm saltwater mix, when the color of the blade turns to a low red heat immediately dunk it in the water (edge first, not tip first). As it cools don't let go of the blade's tang, keep it edge down and don't let it turn to the side. You will see the blade bend down than curve up. Pull it out when there is no more bubbles coming out of the water. And the rest is simply cleaning the blade and polishing it. Using this method I made a sword from a cheap mid A36 steel that could cut 1/2in rebar and framing nails. Have fun.