Originally Posted by
IanS
You have a razor with a 25 degree angle? I'd honestly like to see that. Is it a very old wedge of some sort?
There is a direct correlation between angle of the blade and cutting ability, so I'm sorry but your experience only proves that with two different blades, at two different angles, you can't find a difference in shave quality. Forgive me for saying it, but arguing that something which undeniably reduces the blades ability to cut can not degrade the quality of the shave seems very pertinacious to me. And I would proffer that there really is no way to tell regardless of how much experience you have, as the change takes time, and I doubt anyone can with a straight face compare particular shaves many years apart. So I'm going to claim that this much is necessarily trusted to theory. And simple knowledge of cutting properties should be enough to convince anyone that a change in blade angle will at the very least change the shave. I personally feel that under almost all circumstances, reducing the prospective sharpness is a step down in shave quality. Others are free the feel the opposite, or feel that the respective traits that are changed are not noticeable to them or else balance each other out.
I suppose it could be tested with some degree of reliability by purchasing 2 identical razors. Something cheap. Gold Dollar would work.
Find two similar specimens (after honing) compare their shave to ensure there is no noticeable distinction. Then deliberately grind the edge of one down several mm. Do the same to the other but leave the spine intact through taping. Then do a single shave, comparing the two. It's not perfect as there may be distinctions that are noticeable further down the blade, but it's as close as we'll get. I'm quite confident the difference, when immediate, will be noticeable.