The type and size of the blade being sharpened determines the size of the stone needed. In general , a 6" stone is considered a small sharpening stone, an 8" stone is a common larger size, and a stone larger than 8" (10"-12" are available) is considered generously sized. Stones smaller than 6" (3" and 4" stones are quite common), are considered pocket stones and can be used for toolboxes, tackle boxes and on-the-go sharpening, but are generally not recommended for regular sharpening jobs. 

We offer a series of oilstone packages that combine India and Arkansas stones and are very reasonably priced. At 8" long by 2" wide these stones are not as wide as some other types, but still wide enough for many edges and are plenty wide for knife sharpeners. Available in four price levels, these kits are a great opportunity for the beginning sharpener on a budget.
A: Another issue that comes up with electric knife sharpeners is how to clean them. Or if, in fact, they actually need cleaning at all. The answer to the second question is that yes, they do need to be cleaned occasionally. And by occasionally we mean once a year or so if you use them with any frequency. Obviously if you’ve only used the sharpener a few times then there’s no compelling reason to clean it, other than just wanting to keep things tidy (and there’s nothing wrong with that). So, having established that sharpeners do need to be cleaned occasionally you need to know how to do so in a safe and effective manner. It’s not complicated.
There will be a drawer that extends into the mechanism under the abrasives. Any detritus from the sharpening process drops into this drawer. Exactly where the drawer is located will differ from sharpener to sharpener but it shouldn’t be hard to find. Remove the drawer flick any material into the wastebasket and then wipe out the drawer with a damp cloth or tissue. You may want to use work gloves and goggles to protect your hands and eyes from any loose metal shavings. Once the drawer is clean and dry replace it. The exact means by which the sharpening mechanism itself is cleaned will vary from manufacturer to manufacturer. Consult your owners guide for specific details. Make sure you don’t introduce any grease or other lubricants into the sharpener unless specifically directed to do so by the owner’s manual. Also, the outside of the sharpener should come perfectly clean with just a damp cloth. Avoid using commercial cleaners or abrasives of any kind.
However, due to limited natural deposits and extensive quarrying over the centuries, true, high quality, Japanese water stones are now few and far between and are very expensive. Thus, various companies are now producing synthetic Japanese Water Stones which generally have a more consistent composition and grit size than natural stones as well as often begin somewhat harder and thus, lasting a bit longer; not to mention being cheaper to purchase.
One more thing to consider before you proceed is if you would like to sharpen your knife freehand or use a guide such as the DMT Sharpening Guide. Your skill and experience in sharpening will help you decide on the method that's best for you. If you are experienced and comfortable with freehand sharpening, a knife guide may be unnecessary. On the other hand, a knife sharpening guide is an inexpensive and easy way to keep the angle consistent. If you have tried to sharpen before but never achieved the proper edge, we recommend using the sharpening guide. The guide can solve common mistakes in the sharpening process. If you choose to use a guide, please read our how-to for using the knife sharpening guide.
Sharpening is really two processes: Grinding and honing. Grinding is simply the removal of metal. Honing is a precision abrasion process in which a relatively small amount of material is removed from the surface by the means of abrasive stones. Once you have the right shape, usually using a more aggressive grit, you then switch to a finer grit to hone the edge.
The 8,000 grit Kitayama is definitely a popular 8K stone, it is my favourite, and the feedback has much to do with that. It is silky smooth and feels creamy when you use it. When reaching refinement levels of 6k and above, polished bevels/edge are inevitable, and often sought after. The level of polish from this particular stone is very beautiful, assuming that you have done some refinement prior to this but it is a wonderful 8,000 grit stone.
Modern synthetic stones are generally of equal quality to natural stones, and are often considered superior in sharpening performance due to consistency of particle size and control over the properties of the stones. For example, the proportional content of abrasive particles as opposed to base or "binder" materials can be controlled to make the stone cut faster or slower, as desired.[7] Natural stones are often prized for their natural beauty as stones and their rarity, adding value as collectors' items. Furthermore, each natural stone is different, and there are rare natural stones that contain abrasive particles in grit sizes finer than are currently available in artificial stones.[citation needed]
Steeling helps maintain sharpness. This process realigns the edge, correcting for dulling causes such as a rolled edge. A sharpening steel is a type of hardened cylindrical rod used similarly to honing stones. For example, a butcher steel is a round file with the teeth running the long way, while a packer steel (used in the meat packer's industry) is a smooth, polished steel rod designed for straightening the turned edge of a knife,[7] and is also useful for burnishing a newly finished edge. Because steels have a small diameter they exert high local pressure, and therefore affect the knife metal when used with very little force. They are intended for mild steel knives that are steeled several times a day, but are not well suited for today's tougher and harder blade steels. Diamond steels are now available that have an industrial diamond coating and can remove blade metal as well as straighten, therefore used correctly they can re-profile a knife instead of just honing.
Now you may wonder, if a finer stone produces a better cutting edge why do I need a coarse stone at all? The answer is that finer stones work much more slowly than coarse ones. The amount of metal a fine stone removes with each pass is much less than what a coarse stone removes. If you have an edge with a good shape to it from a coarse stone, this is not a problem because the fine stone doesn’t have to remove much metal to improve the edge. If the edge is dull, it will take many times longer to reshape it with a fine stone than it would with a coarse one.