When I looked for some ceramic knife sharpeners for testing, I found one in our discounted wholesale store. The manual (handheld) sharpener for steel and ceramic blades- ADLER europe AD6710 (the price was 12 €).
CERAMIC KNIFE SHARPENER ADLER AD6710
ADLER AD6710 has 3 phases. One phase with diamond rollers for ceramic knives. Second with hardmetal segments for steel knives and the third phase with ceramic rollers for final smoothing and polishing.
I took for the experiment such ceramic knife:
The knife was not completely new. I used it for conventional cutting in the kitchen for about a year thus resulting in decreased sharpness due to very fine chips on cutting edge ( edge is in detail at 250x magnification):
Blade before sharpening
I decided to make the test, if the sharpener ADLER AD6710 helps me to get my ceramic knife again sharp.
Briefly about ceramic knife sharpeners features -this sharpener has plastic body and robust and good looking design. Is for right- and also for lefthanded, has ergonomic grip handle and on the bottom has non-slip safety cushion.
In the instructions was written – first put the sharpener on the table. Then grasp the handle and insert the blade into the shift. Pull the knife several times towards to yourself, until you have the feeling the blade is sharp again.
That was theory and then followed the practical test.
I unpacked the sharpener from the box, stood it on table and began sharpening. At first I put the knife into first phase for ceramic knives. After a few strokes I could see white ceramic powder -clear sign of grinding. Then I ended polishing in the last phase. I wondered, again white powder appeared. When I checked the result under microscope (detail 250x) – there are clearly visible traces of sanding and incredibly gritty cutting edge:
Blade after “sharpening”
If before sharpening was the blade just gently chipped, after sharpening it was just pure disaster – on the blade are still the chips, it’s totally dull, so I can go through it with my finger without fear that I would cut myself. Also the checking test with the cut on the paper went not to satisfaction.
The result of this test is – I definitely do not recommend such ceramic knife sharpeners for sharpening.
In my opinion – there are 2 factors causing this sharpening disaster:
- The diamond grain is terribly coarse. So that’s why the knife edge is chipping by multiple pulling the blade between diamond cylindrical elements
- The possible reason could be change in angle during sharpening. During pulling between the cylindrical elements I probably unconsciously several times changed the angle under that I pulled the knife.
In my next test I'm gonna to try the handheld sharpener from Tescoma.