Directions for using the 30000-grit Shapton Honing Stone of the Ha-no-kuromaku Line
This text is a translation from the factory directions for using the 30,000-grit Shapton sharpening stone, and so can be taken as the direct recommendation of the manufacturer.
The soft plastic lining in the box is there to protect the stone during transport to the buyer's workshop, and should be removed and discarded. The 30,000-grit sharpening stone is purple colored and should be placed in water about 10 minutes before use, so that it has enough time to soak up the water that lubricates the stone while sharpening. It should not be left too long in the water though, as this will tend to soften the surfaces of the stone too much. One should never store the stone in water! After use, it should be left to dry, and then stored in the plastic box provided.
Honing with the 30,000-grit stone goes quickly when the edge has been properly prepared using a series of progressively finer stones. Normally one starts with the 1,000-grit stone (orange), and then works up through the 2,000 (green), the 5,000 (wine or "burgundy"), the 8,000 (melon) and then gives the blade a final honing with the 30,000-grit (purple) stone.
It is a good idea to sharpen as little as possible on each individual stone: this will reduce the degree to which a hollow is worn in the surface, and so increase the sharpness of the edge that it is possible to obtain. This is only possible when one has enough different stones to work with. If one uses too few, then one must work longer on each stone, and the stones are hollowed out more quickly.
To obtain the finest edge it is also important to clean the slurry of water and grit produced in sharpening off of the tool, one's hands, and the work surface and even from under fingernails. This is to reduce the chance that larger grits from one stone get transferred to the surface of the finer-grit stones.
The sharpening stone must be absolutely flat to produce an optimal edge. To flatten a hollowed stone, take a second stone (it should be finer than 1,000 grit) and rub the two faces together. Both stones should be soaked in water for 6 -10 minutes before this, and the surfaces of the stones wiped off so that pooled water cannot cause the stones to cling to one another and hinder the process. The second possibility is to use a truing stone. Always be careful to thoroughly wash the stones with water after flattening to remove loose grit.
Frequently Asked Questions
Question: After honing a knife with the 30,000-grit "purple" stone, I found big scratches on the blade.
Answer: When one moves to the honing stone after sharpening with the coarser stones (orange, blue, green, melon) and one has not thoroughly cleaned hands, work surface, and the knife, larger grits will be carried over onto the surface of the fine stone, and leave scratches in what should be a mirror surface after honing.
Question: I flattened the 30,000-grit "purple" stone, but it doesn't cut as well as before.
Answer: The stone is too rough. Try to resurface the stone with a finer abrasive (a finer sharpening stone, some silicon carbide powder on a truing stone) to make it smoother.
Question: I used a truing stone and silicon carbide powder to resurface my 30,000-grit "purple" stone, but the surface is still too rough and doesn't have the hard, almost mirror smoothness it should.
Answer: The underlying problem is that the stone was left too long in the water bath and the surface is now too soft. Take the truing stone, and use a coarser grade of silicon carbide powder to grind down through the softened layer of stone to reach the harder underlying stone. Then go back over the stone with the fine silicon carbide powder to get the optimal surface.
Question: When I am using the ultra-fine "Purple" stone I get the feeling that it isn't actually doing any sharpening.
Answer: When you are using the "Purple" stone to finish hone an edge and it feels like it isn't really removing any steel or sharpening as other stones do, this is usually because one is working on too wide a surface. The stone is designed to be used on just the last millimeter of the edge, and if used properly will leave the blade sharper than it has ever been before.
Question:I would like to try to use the "Purple" stone. The directions suggest that I should use it as the final step after honing the edge on the "Melon" (8,000-grit) stone. But can I use it after honing with the "Cream" (12,000-grit) stone, because the "Cream" stone is finer than the "Melon" stone?
Answer: Before finishing with the "Purple" stone, the "Cream" stone should be used to hone very hard steels. With softer alloys and steels, it is better to use the "Melon" stone and then move to the "Purple" stone.
Question: I use the plastic box to hold the stone during sharpening. The stone moves around on the box, making it hard to sharpen properly.
Answer: Lay a piece of paper between the stone and the plastic box.
Question: I use the plastic storage box to hold the stone while sharpening. Even with the rubber feet, the box moves around and hinders sharpening.
Answer: The rubber feet do not hold well on some materials. Lay some paper or a rag between the box and the work surface.
Question: I flattened the 30,000-grit "purple" sharpening stone with a truing stone and fine silicon carbide powder, but the surface doesn't look as good as it did when I bought it.
Answer: Before flattening, lay the stone in water for 6 - 10 minutes. If that doesn't solve the problem, use a bit more silicon carbide powder.
Question: My 30,000-grit "purple" stone has unfortunately become too soft.
Answer: oftening or other changes in the substance of the stone mean that it was left in the water for longer than 30 minutes or was somehow exposed to a detergent. If one also uses a wooden support for the stone, and that becomes wet in use, the stone can suck moisture from the wood, keeping it wet longer than it should be. If the stone is too soft, one must simply grind down to a firm surface. Sand the soft layer off with a coarse sharpening powder, rinse and clean the stone thoroughly with water, and then use a finer silicon carbide powder to finish the surface. Afterwards, allow the stone to dry and store the stone in its plastic box.
Question: Which side of the 30,000-grit "purple" sharpening stone should I use?
Answer: Use the side without the writing first.
Question: My 30,000-grit "purple" sharpening stone has developed small cracks.
Answer: If the stone is not used often enough, or if it is mishandled, small cracks can develop. Sand the stone until the cracks are no longer visible. Small cracks are not very deep. The stone should be resurfaced as soon as possible if one notices cracks developing. The smoother the surface of the whetstone, the less likely it is to crack.