I got my shapton stones the other day and tried lapping them today. I bought a 1k, 4k, 8k and 16k shapton ceramic on tempered glass. I lapped the 16k and 1k today on my DMT D8C. The lapping went fine but took some time as the glass is a lot harder than a coticule or a norton stone. I did the lapping in the sink and used my DMT holder in the bottom of the sink to hold the DMT so I could lap the shapton on top of it, I think it took me around an hour or a little more to lap the two stones with the DMT, but I was able to get both of them lapped so that after applying grid-lines with a pencil they come off almost immediately when lapped for a few seconds on the DMT.

I did try holding the two stones together in my hands at first under running water like I would with the norton or a coticule but that was taking a long time and starting to get a little hard as I had to hold up the DMT. I didn't keep the water running the entire time while lapping these with the DMT in the holder though. I ended up just running the water to clean off the DMT and shapton often and to reapply a bunch of water to the DMT surface so it would move freely across the surface.

Any of you that have the shapton GDLP have the experience go faster or does it still take some time? I was reading on the shapton webpage that the DRLP only takes around under a minute to lap a shapton stone. At $500 or so new and $325 for a remanf. one or $289 for the GDLP I think I'll stick with my DMT that I only paid $120 for a set with the D8C, D8F and D8E and a holder for them though, I don't think I'll end up needing to lap them enough to really justify the purchase. Also I think after the initial lapping and with their use solely for straight razors subsequent lappings of these will probably be pretty quick. Now I just have to lap the 4k and 8k stones but I'll leave that for another day or maybe later today.