What are Slip Stones?
Slip stones are sharpening stones shaped to fit the inside bevel of tools like gouges, v-tools, or knives with a concave edge such as hawkbill knives. Their defining characteristic is having at least one rounded or tapered edge.
With regular bench stones, you use the largest surface to sharpen. It’s completely different with slip stones. Their usefulness comes from having a small sharpening surface that can fit edges that can’t otherwise be sharpened on a regular bench stone.
The outside of a gouge can be sharpened on a regular bench stone. The narrow, round edge slip stone is needed to reach the gouge's inside bevel.
To fit inside different tools, slip stones come in a variety of shapes and sizes. The most common is called a round edge slip. The thick and thin long edges are rounded to fit inside the radius of tools such as gouges. You can also use these slip stones for concave knife shapes like hawkbill or billhook knives. They can also be used to sharpen the gullets of serrated knives.
Other slip stones taper to an edge. These are great for sharpening v-tools. Some slip stones will combine rounded and tapered edges for greater utility in a single stone (such as the Norton India Multiform Superslip). Slip stones with a rounded convex surface will sometimes have a concave surface on the opposite side for sharpening the outside bevel of gouges (such as the Norton India Gouge Stone).
Different shapes of slip stones are used to sharpen different carving tools. A gouge requires a different slip than a v-tool.
It’s unnecessary to have a slip stone fit the inside bevel exactly. So long as the slip stone is small enough to fit the inside of the tool, you can just move it along the edge to sharpen. However, a closer fit will result in faster sharpening as more of the bevel is in contact with the stone during each pass.
The Norton Round Edge Slip works great for sharpening gouges. Match the slip to the size and sweep of the gouge. Your slip should have a smaller radius than your gouge.
A v-tool requires a slip with a knife edge.
Slip stones use the same abrasives as bench stones. We have diamond, silicon carbide, aluminum oxide, ceramic, and Arkansas stone slips, all in a variety of shapes. Like bench stones, it’s recommended to have a range of grits. Coarse for quickly raising a burr, medium for refinement, and fine for creating the final sharp edge.