The range of sharpening media for hand-honing applications is fairly well covered by oilstones, waterstones, diamond plates and honing film. Each of which has its own pros and cons, adherents and detractors (this is interesting: http://blogs.popularwoodworking.com/editorsblog/Tool+Review+WorkSharp+To+Sharpen+Wide+Tools.aspx or http://tinyurl.com/yggz25a). You may, and probably do, have one or more of each of these abrasives, and that being the case you’ve probably joined one camp or another. If not, the following posts are for you.
Different tools require different abrasives and techniques. Sharpening a carving gouge applies considerable force against a small area of the abrasive surface: force enough to crush a groove into a soft stone, and hence a harder stone is called for. Chisels and plane irons need a surface that is flat, one that stays that way or is easily re-flattened. So, one must consider which tool will be sharpened when shopping for stones or whatever.
According to the survey (url above), waterstones are the most popular abrasive for sharpening. As their name indicates, waterstones are used with water to both lubricate the grinding action and to remove the swarf (the slurry of steel and abrasive particles) from the surface, keeping the grit grains exposed to do their job efficiently. Some brands need soaking in water and can even be stored in water while others, so-called ceramic waterstones, are used with a splash of water and are never soaked. Either way, you’ll have water around when using waterstones, so protect your project’s surfaces. Also, protect your steel tools and parts to avoid rust. I recommend some sort of stone pond to mitigate the mess – Shapton, Veritas, maybe Rubbermaid. Apron, paper towels, WD40 also go on the recommended accessory-list for waterstones.
In general, waterstones cut very fast due to their friability (they wear down easily, exposing fresh, sharp grit all the while) — we like this about them. They are truly self-sharpening – refreshing themselves while you’re using them. But they may not be wearing flat while doing so.
Flatness is a critical feature for the surface that sharpens chisels and plane irons — not so much for shaped edges like carving tools. So waterstones need frequent flattening to get the best from them. You can use specially made flattening devices like those from Shapton or Norton. Or you can use a diamond plate or sandpaper on a flat surface. Some woodworkers just rub their waterstone on a cinder-block or on the sidewalk outside the shop. Others prefer using loose silicon carbide grains on an embeddable surface, such as a sheet of plastic on a flat surface (lapping). The soft plastic immobilizes the grains to lap the stone flat. I’ve used the Shapton stone flattener and it works like crazy but it’s expensive. Norton’s stone flattener needs occasional flattening itself (much less often than the stones do) but does a fast, aggressive job truing up the stones.
The photo shows a Norton 8000-grit waterstone alongside some silicon carbide grains on a piece of glass for lapping. The grains and glass are part of the Veritas Stone Pond which includes a sheet of plastic that goes between the grains and the glass to embed the grains during lapping. Next to that are a Norton Stone Flattening Stone and a Shapton LapPlate, both on a sheet of Wet-or-Dry silicon carbide sandpaper. (Cinder block and sidewalk not show.)
The Norton and King are two brands of stones that are soaked before using. I store mine in a Rubbermaid container and two of them have been soaking continuously in there for many years. They cut aggressively and do a great job of sharpening. I flatten them before each use. I’ve heard complaints that these stones are so soft they sometimes need to be flattened while sharpening one blade. If that’s the case, you may be skipping an abrasive step and asking a too-fine stone to do more than its share of the work, thus wearing it too quickly. If you try to jump from, say, a 500-grit stone to a 4000-grit one, the 4000 may take too long and you may wear it down too much. Adding an intermediate grit or two should be more efficient.
The Shapton and Naniwa Super Stones are examples of the no-soak ceramic waterstone. These are formulated differently and need only a splash of water to perform their best. They must be kept wet during use, but not soaked or stored in water. Because of the ceramic formulation, they tend to stay flat longer. I found both brands to work very well and even though I flattened before each use they needed only a quick truing up.
The initial buy-in for waterstones may seem steep but they last a long time and your investment will pay off in the long run. If you are unsure of what grit sizes to buy, I’d suggest asking your woodworking friends what they use and perhaps trying and testing their stones. Or visit a woodworking supply store to try out their demo models. If a sharpening class is being offered it would be a great way to learn and experiment with different abrasives. Honing films as sharpening abrasives will be the next blog topic. They offer an inexpensive way to learn which grits you like the most – intel you can use when you’re ready for the leap to waterstones. And I’m hoping this post will generate a few suggestions for grit sizes, brands and suppliers in the comments below.
Next: Abrasive Personalities, Part II — Honing Film