How to improve your carving knife?


blunt to sharp
Although soap is relatively soft material, knife may slowly get too blunt over time. Fortunately, knife can be sharpened to be suitable for carving again. Here I tell you, how to do it using sand paper.
⚠️ Sharpening can be applied only to carbon steel blade knives. The stainless steel knives are too hard to sand.

What you will need

  • Exacto knife
  • Waterproof flat board
  • Waterproof work table e.g. vinyl tablecloth
  • Wet/dry sandpaper of 3 kinds of grit*:
    • 120-150 grit
    • 400-600 grit
    • 1500-2000 grit
  • Water


  • Gloves (to keep hands clean)
* There are multiple standards of grit measure. If grit measure system is different in your country, refer to this page.

Instruction video

Note: instructions on how to improve the Exacto knife are shown from 0:06 to 4:50.


1. Prepare sandpaper of grit of about 120 to 150. I have used 120 grit.
step 1
2. Drip a little water.
step 2
3. Sand the blade against the cutting edge to make it thin. Do not sand the cutting edge.
step 3
4. Repeat on the other side. Sand against the cutting edge.
step 4
5. Sand well the point of the blade to make it thin.
step 5
6. Sand against the cutting edge in the same way with 400 to 600 grit sandopaper. I have used 600 grit. Repeat on the other side.
step 6
7. Sand the blade against the cutting edge in the same way with 2000 grit sandpaper. Polish the blade by sanding with fine grit sandpaper.
step 7
8. Done. The blade became so shiny. A very thin blade is appropriate for soap carving. Make your blade as thin as you need.
step 8

References and Resources