The 1x4 Naniwa 320 Pro stone workhorse coarse stone used for profiling, repairs and initial maintenance on your edges.  Not found outside of Japan, this stand-alone Naniwa stone is close in formulation and feel to the Naniwa Chosera line, and we really don’t know why it didn’t make it into the final Chosera lineup because we feel it is the very coarse grit stone the lineup is missing at the lowest end. This stone is hard and aggressive, and really cleans up deeper factory scratches, makes transitioning from diamond plates and stones easier and cleaner, and is a good coarse foundation stone before progressing to finer grits.

This stone is 1" x 4" in size mounted to an aluminum blank with a total thickness of 5-6mm and used with water only. It works best when soaked in water for a minute or two before use. Let air dry and store dry when not in use.

Abrasive Material: Aluminum Oxide

Ideal place in a sharpening progression:

• Starting grit for factory edge knife and profiling.
• Starting grit for repairs on a dull edge.
• After any diamond grit plate or stone to remove the deeper diamond scratches.
• After lower grit sharpening stones (80, 120, 180, 220 grit)
• After coarse belt grinder grits (60, 80, 100, 120, 220, A65, A30 Trizact grit)
• Before progressing to a finer and/or medium grit stone (400 - 2K grit)

The Naniwa 320 Pro sharpening stone is a premium sharpening stone at a less than premium price that works on almost all types of knives, scissors, tools and chisels, including those made with abrasion resistant steels. While the 1x4 size is meant for use with the KME Sharpener, it is also a great size for a slip stone, field stone or a pocket stone for knife repairs and sharpening on the go.

This stone can also be used in a mix and match progression with other synthetic and natural sharpening stones as well as with other brands, such as Shapton, Sigma, Suehiro, Imanishi, Spyderco, King, etc. The Naniwa 320 Pro is a Waterstone but can be used in conjunction with oil stones (such as Norton India and other carborundum and Arkansas stones) if the blade is wiped clean before and after switching stone types. 

On More Traditional Carbon Steel and Stainless Steel Edges the Naniwa 320 Pro works on steels between RC 52 and RC 65 on the Rockwell C Hardness scale. The stone itself is very solid and aggressive, and makes easy work or profiling, sharpening, and repairing of the softer end of the spectrum of steels like X50CrMoV15, AUS6, 440B, and most steels used by many kitchen knife makers like Henckels, Wüsthof, Gunter Wilhelm, F Dick, Victorinox, etc.

On the higher end of the hardness spectrum of traditional steel edges made with steels like 1095, 52100, 440C, Aogami White, Shirogami Blue, O1, W1, etc. The Naniwa 320 Pro removes surface rust reestablishes the bevel and edge and leaves a clear and consistent scratch pattern. The very solid stone allows for more pressure to be used in order to get some work done without the worry of the stone dishing so fast.

On Carbide Forming Steel and More Abrasion Resistant Steel Edges such as VG-10, D2, M2, S35V, S90V,etc., The Naniwa 320 Pro stone still removes matrix steel and carbides without much problem and is best utilized for removing and cleaning up diamond plate or belt sander scratches to prep the edge for a more even surface before going to finer grits. 

Hacks and Tips:

• For a more aggressive stone, create a slurry by rubbing the stone’s surface with a smaller 320 grit stone, or a coarse or extra coarse diamond plate and some water. The slurry will be a pasty olive green.
• Use a moderate amount of water when sharpening with this stone to avoid the black swarf from turning into a thick paste. A cleaner, more viscous surface will cut faster than a thicker pasted one.
• Lap this stone with a coarse or extra coarse diamond plate, silicon carbide (SiC) powder, or low grit wet dry sand paper to keep it consistently flat and clean.

Comparable Stones: Jende 320 Platinum, Shapton 320, Suehiro Cerax 320