I checked it under a magnifying scope from what it was to begin with which was almost on the iron's cutting edge and it was less then the shavings the planes took previously which a 1000th or so. I planes the following boards cherry,walnut,white oak and what either black locust or locust not sure. On my magnifyer you can set it over an object and set lines that stay in place[used for machining of some sort] so it was easy to see a slight difference in the one that moved closer to the edge.I also question how long that edge would have held up in use since it was so close and it appeared to be folding up slightly at the very edge under the magnification.Both the irons were Sheffield cast tool steel irons by the same maker of the appropriate period the infills were made[1880's] and they were the makers choice in there planes at that time. Both were sharpened the same as all my irons using a Tormeck,water stones through 8000 grit then stropping with green rouge. Len