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I just got a Chinese and started to lap it w/ my Norton Laping stone. Not sure it did much but grind the Norton. I'm wondering what grit of sandpaper to use. The Chinese is so fine i'm afraid to use 300 grit, however any finer grit may not make a dent. any ideas?
Thanks Al
Many lap it on a DMT 325 mesh, so maybe 300 paper would be ok. You could finish it up on a finer grit paper.
Mine was lapped on a DMT and it took a while. (Depending on how close your specimen is to being flat-from-the-factory)
Given the hardness of the Chinese stone I don't imagine you need to worry about imbedding grit from the paper so I would think that the paper would be fine. Smoothing it on finer grit paper like Sticky said wouldn't be a bad idea. I lapped my Belgian blue and coticule on 300 grit paper and both were fine. Just make sure you clean the stone to get rid of any loose pieces of sand paper grit.
It sounds like you have already given up on the Norton lapping stone but just in case you haven't, don't use it for the 12k. All it will do is trash you Norton and just mildly annoy your 12k
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As a general rule, I would say the Norton lapping stone is fine for Norton hones but should never be used on a natural stone or barber hone.
I utilize the chinese 12K very often in my final polishing. I have found that the DMT 325 coarse or the DMT 600 works the best and fastest. With the DMT 325, it will still take about 30 minutes depending on how flat your chinese 12K is to begin with. It is a very fine and HARD natural stone!
I lapped mine with 400 grit wet/dry on the kitchen counter. I was prepared for the worst after reading the horror stories of chinese 12k lapping, but mine only took about 20 minutes and 2 sheets of paper. Guess I got a softer stone :shrug:
There is one area right near one of the ends that still had some pencil marks. I decided I wasn't going to work that much to get that part flat and I just stop an inch or so before the end when I'm honing.
I lap my Chinese 12K & most other stones on a big slab of tempered glass using water based automotive valve grinding paste - coarse thru to fine grit. The paste breaks down into a slurry quickly and doesn't take long to do as I'm not limited to a 12" square piece of paper. It's basically a mix of Silicon Carbide & Aluminum Oxide and no, it doesn't embed in the glass or the stones same as wet 'n' dry doesn't.
VIP ---- Use only water based valve grinding paste. Don't use oil based abrasive on your waterstones.
Oz,
what brand did you use?
Al
Brand's not an issue but last one I bought was Holt's .
Any brand that says something like 'Use no oil or petrol. Thin with water only' on the instructions is fine.
You can be sure it will be oil free :D