A good knife is likely to be the most important tool in your kitchen so it's wise to keep it razor-sharp. One of the best ways to sharpen your knife is to use a whetstone - it takes a little time and patience but, once you've mastered it, you'll never have to battle again with a blunt knife.
How to use Langxun whetstone.
1. Submerge your whetstone in water for between 10 to 15 minutes.
2. Place the whetstone onto the base which it will not slip. Place it with the coarse grain facing up.
3. Let the angle guide (If you have) Mount to the knife surface.
4. Hold your knife firmly. Place your blade at an angle of approximately 20° to the whetstone. To get this angle, place your knife at 90°, half this to 45° and half again. The angle of your blade is important and some knives will require slightly different angles (for example, Japanese knives) so you may need to do some further research on your particular knife.
5. Place an even and gentle pressure on your knife and draw the blade along the stone from tip to hilt. Repeat a a couple of times. Then turn the knife over and repeat on the other side. It's important to repeat exactly the same process on the other side of the knife (unless you are dealing with a Sashimi knife or something similar which will require more technique).
6. Test your knife (be careful not to cut yourself). You can test it using some fruit instead of your finger!
7. Turn over the whetstone and repeat the process using the finer grain.
8. Repeat the process on both sides of your knife.