How to Sharpen a Serrated Knife with the DMT Serrated Knife Sharpener

Serrated knives are designed to stay sharp longer than straight-edged blades. Their pointed teeth and scalloped gullets make it easy to saw through crusty bread, slice tomatoes cleanly, or cut rope and fibrous materials with minimal effort. But over time, even the best serrated knife will start to lose their bite. The challenge for many sharpeners is figuring out how to bring those teeth back without grinding them away.

At Sharpening Supplies, we carry sharpeners designed for exactly this purpose. The DMT Diafold Serrated Knife Sharpener is one of the simplest, most effective ways to restore your serrated edges. Its tapered, diamond-coated rod is perfectly shaped to fit a wide range of serration sizes, from the large scallops of bread knives to the finer gullets often found on pocketknives. In this article, we’ll walk you through step-by-step how to sharpen a serrated knife using the Diafold, with tips to keep your knife performing like new.

Why serrated knives need a different approach

Unlike straight-edged knives, which are usually sharpened on flat stones, serrated knives have alternating points and valleys. The points bite into the material, while the valleys (gullets) slice into the cut. To sharpen them properly, you need to focus on the beveled side of the serrations, working inside each gullet.

You can improve the edge with just stropping but eventually the teeth will wear down and the gullets will become blunt. Trying to sharpen a serrated knife on a flat stone usually removes too much metal, flattening the teeth and shortening the life of the blade. That’s why a specialized tool like the DMT Diafold is essential. Its tapered shape lets you match the original grind of each serration so you preserve the original edge geometry.

Tools you’ll need

• DMT Diafold Serrated Knife Sharpener (for sharpening inside the gullets)
• A fine flat stone or leather strop (for deburring the flat side)
• A marker (optional, to help find the sharpening angle)

Step-by-step guide to sharpening with the DMT Diafold

1. Clean the knife
   
   Start with a clean blade. Wipe off any food or oil so you can see the serrations clearly and feel for burrs as you sharpen.

2. Identify the beveled side
   
   The top image shows the beveled side, and the bottom image shows the flat, back side. 
   
   Most serrated knives are chisel ground, one side is beveled, while the back is flat. You’ll sharpen only the beveled side with the Diafold. The flat side is left alone, except for a quick deburring step at the end. 

3. Use a marker for guidance
   
   Color the serrations on the beveled side with a marker. As you sharpen, the ink will be removed exactly where the Diafold contacts the bevel. This helps you stay on the correct angle.

4. Match the taper to the gullet
   
   The Diafold rod is tapered so it can fit different serration sizes. Position the rod so it fills the gullet without riding up onto the teeth. This keeps you from accidentally flattening the points.

5. Set the angle
   
   Rest the rod against the bevel inside the gullet. Most serrated edges are around 20°, but the key is to match the existing sharpening angle.

6. Sharpen each serration
   With light pressure, move the Diafold through the gullet, moving away from the cutting edge. Make enough passes per serration to raise a burr, rotating the rod during each pass to use fresh abrasive.

7. Work your way along the edge
   Continue sharpening each gullet from the heel to the tip. Take your time to stay consistent. Serrations don’t take much metal removal to come back to life.

8. Check for a burr
   
   After sharpening a serration, gently run your finger along the flat side of the blade. You should feel a slight burr forming. This is a sign that the edge is apexed.

9. Remove the burr
   
   Lay the flat side of the blade flat on a fine stone or leather strop. Make several very gentle, edge-trailing passes to remove the burr. The goal is to deburr without rounding over the points.

10. Clean and test
    
    Wipe the knife clean. Test the edge by slicing paper, a tomato, or rope. A sharp serrated knife will bite immediately with minimal pressure.

Tips for success

• Light pressure is best. Diamond abrasives cut efficiently, so let the tool do the work.
• Touch up early. Don’t wait until the knife is very dull, a few strokes per gullet as soon as you notice slipping will keep the teeth sharp and intact.
• Store the Diafold near your knives. Its folding handle makes it compact and safe to carry in a drawer, kitchen, or gear bag, ready for use.

The right tool for sharpening serrations

Sharpening serrated knives doesn’t have to be intimidating. With the DMT Diafold Serrated Knife Sharpener, you can restore your favorite bread knife, pocket knife, or utility knife in minutes, all while preserving the serrated pattern. If you’ve been avoiding sharpening your serrated knives because you thought it required special equipment, this compact, easy-to-use sharpener is the solution.

Shop the DMT Diafold Serrated Knife Sharpener here and keep your serrated knives sharper than the day you bought them.