General question concerning Showa era blades

[blucool]

I've read that a large percentage of blades crafted during the Showa era were oil quenched as opposed to the traditional water quenching. Is there a way to tell the difference between oil and water quenched blades just by appearance alone? Also, why is an oil quenched sword considered less desirable than a water quenched blade, all other things considered equal. Thanks!

[QuangD]

Blucool,

 

oil is cooling the blade slowly rate so the chance of steel cracking is more less. With water, cooling down the blade at a faster rate so the chance of having a crack in the temperline is higher. With the high demand of swords during the WWII, some smiths will use oil to temperline the blade to meet demand. As a collector, people prefer to collect water temperline sword as to oil temperline.

[Grey Doffin]

My understanding of the difference between water and oil quenched blades is that the oil quench leaves a very uninteresting, sleepy hamon and no possibility of ji-nie. A well made oil quench blade should look like a very poorly made water quench. Grey