The card stock one think it was Best steels for edge retention. Graph showed thinner the edge grind more cards can cut. I could tell you that all the years in front of cutting boards. Grind is everything. It was good to see it on a graph. Slicing lemons with pocket knives not the best blade to test with. Again thin grind carbon knives can slice lemons quite a while slicing through the seeds instead of displacing them. Have watched NHK world on Japanese limes slicing with carbon super sharp blades clean cuts through the seeds. Acidic foods dulling knives is exaggerated again it is more about grind & edge sharpness. One thing is Knife Steel Nerds threads I always have to check it out. No matter if I understand it all or not.