Originally Posted by
JimmyHAD
I've got the 20mm Naniwas and the 15mm Shapton pros. IME either of these polymer resin based hones have to be flattened every honing session. It is a very slight amount and some people might use them without flattening but if you put a pencil grid on them you'll find that over a day or two they will change and will need lapping to be absolutely flat.