Comparing DMT DuoSharp and Dia-Sharp Stones
Should I Get Interrupted Surface or Continuous Surface Stones?
DMT Diamond Stones are available in two main varieties, the Interrupted Surface found on their 6" and 8" Whetstones and DuoSharp stones, and the Continuous Surface found on their Dia-Sharp stones. With two variations in one brand, we're often asked what the difference is and which one a sharpener should get.
When considering the two types of stone, the first thing to know is that they are mostly the same. The diamonds used are the same. The grit ratings are the same. Both types are flat. Both are expected to last equally long, and in most cases, either surface type will do the job equally well. There are, however, differences between the Interrupted Surface and Continuous Surface Stones, and they are worth considering when choosing your diamond stones.
Interrupted Surface Stones Clear Waste for Speedy Sharpening
The yellow (or black, blue, red or green) polka-dots visible on Interrupted Surface Stones are actually holes cut into the the metal plate onto which the diamonds are mounted. The polka dots are the plastic base the metal is mounted on showing through the holes. These holes provide small recesses where the swarf, the waste material produced by sharpening, can collect. This means that the swarf won't clog the spaces between the diamonds and slow the action of the stone, allowing the stone to maintain a fast cutting speed for a long period of time. This is especially important for sharpening jobs that require a great deal of material removal.
The relief holes in the Interrupted Surface Stones do not mean that they are uneven or bumpy. In the majority of knives and tools have enough surface in contact with the stone during sharpening that they simply float over the surface as if the recesses weren't there.
DuoSharp Interrupted Surface Stones are Efficient and Economical
Made with nickel plated steel mounted on a plastic core, Interrupted Surface Stones weigh less and are more portable than Continuous Surface Stones, which are made of a single thicker piece of metal. The DuoSharp line is also double sided so it is offers a more economical solution to purchase two grits.
Continuous Surface Stones are Perfect for Fine Points and Narrow Tools
Most edges do float right over the holes in the Interrupted Surface Stones, but there are exceptions. These exceptions are narrow tools or those with fine points or heavy curves. Any edge shape that results in only a very small portion of metal being in contact with the stone at a time. If the portion of the edge in contact with the stone is small enough, it can become caught in the recesses of the holes.
Continuous Surface Stones have no recessed holes, the diamond coverage is continuous over the entire surface. We recommend using plenty of water with the continuous surface to make sure you're clearing the swarf properly.
Continuous Surface Stones are Great for Lapping
Because they are constructed from a single, machined piece of steel, Continuous Surface Stones are engineered to be even flatter than the already very flat Interrupted Surface Stones. This makes them great for use as precise lapping plates.
When to Get Interrupted Stones and When to Get Continuous Stones
For most sharpeners, either the Interrupted or the Continuous Surface will work well, and a choice can be made on considerations of overall size of the stones and budget. But as a guide, consider the following:
Those looking for stones that are easily portable or who are sharpening large items that produce a great deal of swarf should consider the Interrupted Surface of the DuoSharp or Diamond Whetstones. The Diamond Whetstones offer extra value by including wooden or plastic cases for storage and use. The DuoSharp Stones offer great economy by including two grits on each stone. Available in sizes from 4" x 1" to 10" x 4".
Those sharpening blades with fine points, heavy curves or which are very narrow should consider the Continuous Surface of the Dia-Sharp Stones. The machined steel bases also add an additional degree of flattness to the Dia-Sharp Stones, making them ideal for precise lapping operations. Available in sizes from 4" x 1" to 12" x 3", there are a wide variety of Dia-Sharp Stones.