Making the Chinese 12k perform faster and finer (my secret)
I've gone through about 5 different samples of Chinese 12k, some are finer than others but for the most part, they are pretty consistent.
The way the stone is typically used is with clean water. This is the wrong way, as the stone would have very little abrasive power and is rather scratchy. I get a similar finish to my Naniwa 5k with very light pressure, more like a Naniwa 3k if I use a little pressure. This is too coarse for razors, and very slow.
A much better way is to get a DMT XXC and create THICK slurry with it. Notice that now the Chinese 12k cuts MUCH faster and is just as fine as with clean water. As you keep going, the slurry particles break down until you finally get an ultrafine, milky finish similar to Japanese naturals. It can bring out the hamon in some of my Japanese cutlery.
Keep the slurry thick and use light pressure!
You end up with a finer edge than the typical way of using this stone, while cutting much faster. This same technique also applies to those hard blue Nakayama stones.