The 1x4" Naniwa Chosera 400 Grit stone is a premium level workhorse coarse stone used for profiling, repairs and initial maintenance on your edges. This stone also cleans up deeper factory scratches, makes transitioning from diamond plates, belts, and coarser stones easier and cleaner, and is a good foundation stone before progressing to finer grits. It’s not generally used as a final or one grit stone, but if it is, it produces a very toothy, aggressive edge that can power through most jobs.

This stone is 1" x 4" in size mounted to an aluminum blank with a total thickness of 5-6mm. This stone is used with water only and 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 light repair and maintenance of an already sharpened but dull edge.
• Starting grit for factory edge knife and profiling.
• After lower grit sharpening stones (120, 220, 320 grit)
• After any diamond grit plate or coarser stone to remove the deeper scratches.
• After coarse belt grinder grits (60, 80, 100, 120, 220, A65, A30 Trizact grit)
• Before progressing to a finer and/or medium grit stone (600 - 2K grit)

The 400 Grit Naniwa Chosera sharpening stone 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. Naniwa Choseras are Waterstones 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 400 Chosera works on steels between RC 52 and RC 65 on the Rockwell C Hardness scale. The stone itself is more solid, so it lends itself better to cutting quickly into 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 Chosera 400 removes any surface rust, reestablishes the bevel and edges leaving a hazy gray, consistent finish. The 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 Chosera 400 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 400 Chosera stone, or a coarse or extra coarse diamond plate and some water. The slurry will be milky white.
• 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 sandpaper to keep it consistently flat and clean.

Comparable Stones: Jende 320 Platinum, Naniwa 320 Pro, Shapton 320, Suehiro Cerax 320, Sigma Select II 400, Shapton 500