Thread: Flattening Chinese 12k

Hi All,

I've just notice that my new (ish) chinese 12k waterstone isn't completely flat. It's not far off, only just detectable when i laid it on a piece of glass, but i'm still obsessive enough to want it perfect!

Question is: what the hell do I use to flatten it? i used wet/dry sandpaper on glass for my norton, but it seems that the chinese 12k would be a lot harder. Or am I wrong?

Has anyone flattened one of these before?

Cheers,
Ian.

Originally Posted by taketwoaspirin

Hi All,

I've just notice that my new (ish) chinese 12k waterstone isn't completely flat. It's not far off, only just detectable when i laid it on a piece of glass, but i'm still obsessive enough to want it perfect!

Question is: what the hell do I use to flatten it? i used wet/dry sandpaper on glass for my norton, but it seems that the chinese 12k would be a lot harder. Or am I wrong?

Has anyone flattened one of these before?

Cheers,
Ian.

Hi Ian:

Many of us have lapped a Chinese 12K. Some of these stones as their owners have described the lapping process, seem to be harder or softer. I have a very hard Chinese 12K that took quite some time on a diamond plate (DMT D8C at the time) to lap. Normally on natural stones like Belgian Combos, Belgian Blue, Barber Hones, etc I lap both sides. I stopped after lapping one surface of my 12K because it took such effort and I must be lazy.

Have at it with your wet/dry sandpaper on glass and use lots of water. Draw your pencil grid and sooner or later, the grid will be gone. Then if you're really determined, draw another grid and lap until the second one is gone. Then, happy razor edge polishing!

Chris L

That makes sense chris, I'll give it a go. To be honest, it's probably so close to flat that it wouldn't matter (I've done 4 or 5 razors on it and they went ok). Still, I'm pretty obsessive, and i don't think my sickness will let me leave it alone!!

ian.

I had to lap mine twice.

Some 1k sand paper, something pretty flat to work on and some elbow grease and... voila ...

The second round of flattening is when I learned just how hard these stones are.


Dont forget to knock off the corners and edges. It does make a difference.

I posted this method a while ago for some insight, and I got mixed replies, but this is how I flatten my 12K:

I draw a grid and rub it off with a Norton Flattening Stone. Then I draw another grid and rub it off with 600 grit sandpaper wrapped around a piece of 12" x 5" x 0.25" glass. Rinse and repeat with a freshly drawn grid and a 1000 grit piece of sandpaper.

My 12K is seems really hard to me, compared to my norton, and I've found that this progressive method really makes my 12K feel slick and with three grids to rub off, by the time your finished you may find that you're having trouble peeling the stone from the glass!

I'm also obsessive about flatness!

Good Luck!

I am always amazed when someone describes lapping their 12K with a Norton lapping stone. Mine was way too hard for that and it just trashed my Norton stone without having any effect on the 12K. I guess that's just part of the mystique of using natural stones, like Forrest Gump's chocolates, you never know what you're going to get!

The DMT XXC (125 grit) would probably be the best to do a majority of the work or you can start with a coarse piece of wet/dry sandpaper.
In both cases, once the grid lines are gone from the coarse grit you should then move to a 500-600 grit for 20-30 laps and then to a 1000 grit for 20-30 laps as a finisher. You might even go to 2000 grit. It depends on the texture that you want.

I normally use a 1000 grit finish on my Norton 4/8 but that seems a bit coarse for the Coticule, Escher and Chinese 12K. For those I will be using a 2000 grit as a finish grit.

As already mentioned, be sure to round the edges and corners after every lapping of your hones.

Wrist supports for carpal tunnel syndrome are available at your local drug store!

As I kvetched elsewhere about the phenomenon, the 12Ks are a... son-of-a-gun (expletives deleted for the sensitive of ear) to flatten. I wore out my first coarse DMT trying to lap the 12K. I leaned on the stone too hard while lapping and pulled the diamonds out of the matrix on one end of the plate.

So take it easy, use lots of water, and little more than the weight of the stone on the lapping plate. If you are going to use sandpaper, plan on buying more candles for the cake and invest in Abrasives Unlimited.

It took me about 45 minutes to an hour to flatten the 12k (8x2 version, both sides) with the DMT 8C. I also noticed that the DMT was creating some fine scratches on one spot, I took a screwdriver to it to try to break it in, the scratches were still there. I am not too worried about the scratches they don't seem to effect performance. It really was a pain in the ass, especially after the ease of flattening a norton.

lapped my 12k on 800 grit wet/dry. did both sides and an edge. using the edge for smiling blades. such a difference in the feel of the hone. good luck.

and yeah, the carpul tunnel wrist guards are almost a requirement!!

vgod