Abrasive stropping rapidly micro-convexes the apex. Additional stropping, up to many hundreds of strokes does not substantially increase the micro-convexity.What I meant before was short X strokes. I forgot to type down the key word "short" as well.
I do understand the paste will give different results on leather comparing to balsa, I thought I was clear in my previous message. I am also aware that if I deviate from the "Pasted balsa method" I will get different results. Again, I just reported the results I got with the methods I tried on the skin I have. And again, the steel played a huge role in my experience, so soft steel felt okay-ish on the face but with hard steels it was not comfortable at all.
As for why I skipped 0.25u, the only reason is price. I ended up importing the diamond pastes from USA and I paid 70 EUR for a few ml of one grit diamond suspension. Multiplied by 3, then adding shipping and VAT, that was already the price of a nice Jnat. Although last year I managed to buy big quantities from China for a lot less, but the quality was also much lower. In the end, for that price, I couldn’t expect too much.
Off topic: am I asking too much if I would like a trouble free trade between countries? Maybe my dream will come true one day...
Bevel convexity, as distinct from micro-convexity, is not apparent in sub-micron abrasive stropping, but does occur with larger abrasive particles. The quantity of metal that must be removed to convex the entire bevel will result in blackening of the strop, something generally not observed with sub-micron abrasive strops.
The apex geometry is determined primarily by the strop material rather than the abrasive size.
The transition from triangular to micro-convex bevel geometry can result in the formation of a foil edge burr for resilient (springy) strop materials. This is almost certainly the reason some people are unsuccessful with 0.25 micron diamond spray. If the apex is convexed on a more aggressive strop first, the edge can be finished on that resilient strop without foil edge burr formation.
These observations suggest that a successfully designed stropping progression should involve different strop materials rather than different sized abrasives on the same substrate. This is partly why the traditional combination of linen and leather are so effective at maintaining a straight razor.
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