MDF strop with diamond compound

kwakster

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This type of strop is what i sometimes make & give to people who regularly bring me a CRK or other quality (Chef-) knife for sharpening and/or some TLC, so they can maintain & keep the appearance of their new edge themselves for some time.
Even a few professional Chefs in my area with expensive gyuto's and santoku's in modern PM steel types are using these same strops with good results, so they keep telling me anyway.
I use them myself as well, and they are easy to make.




What you see is a new & cut-to-size piece of clean MDF coated with a thin layer of 1.0 micron (~ 14000 grit) mono-diamond compound, and i put 4 self-adhesive rubber bumpers on the bottom.
These make the strop non-slip plus they elevate the working surface a bit more which makes the strop more convenient to use on a table (more room for your hands)
Due to the harder surface the chances of rounding your crisp apex are also greatly diminished when compared to stropping on compressible materials like leather.
The strop surface can also be cleaned from time to time with a microfiber cloth and some acetone, which will remove all or most of the swarf without removing the diamond particles, as these become (partially) embedded in the MDF surface during the stropping proces.

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But this is (literally) the key element: the placement on rubber bumpers also provides the strop user with acoustic feedback by isolating the MDF from the table (a bit like the bars on a xylophone); you can actually hear when you're arriving at the very apex during stropping movements as the audible sound changes, which makes the stropping proces very easy, even for absolute beginners.



The CRK Nyala used as a prop for the pictures was reprofiled (from 35-40 degrees inclusive to an even 30 degrees inclusive) & sharpened (with 15 micron diamond compound on a Paper Wheel).
The owner only uses this quite expensive knife to cut oranges, about 5 each day, i kid you not.
 
In general i use various professional grade diamond pastes from this US source:.

Consumables - Micro Star 2000 Inc.: Metallurgical Technology Supplier of Materialographic Sample Preparation Equipment and Consumables (https://microstar2000.com/metallography/26/DIAPAT+Diamond+Paste)

These are however rather difficult to obtain in the Netherlands where i live, and not exactly cheap either.
The pro's however are the sheer amount of diamonds in every syringe and their high quality grading.

A cheaper option and still good quality would be TechDiamondTools:

Home (https://techdiamondtools.com/)

Now i haven't used their diamond pastes yet (still have a rather large stock of the other ones), but some time ago i did buy a packet of coarser grit diamond powder from them, and so far this performs most excellent as a replacement for the standard SiC grit on a Paper Wheel.
Very useful for initial edges on especially high vanadium carbide rich steel types.

 
MDF is an interesting material for stropping, indeed. I have used a thin MDF plate with some 3 μm diamond compound on some kitchen knives for a few times and the results were quite ok.

Some issue you might run into though is that the surface of MDF is sealed by the resin that holds the whole thing together. This means that it doesn't hold any cavities that could catch dirt and larger particles of the abrasive – which can promote irregularities on the finish and edge of the blade. A piece of fabric for example can trap large particles in its weave instead of pressing them against the surface due to the lack of softness and holes in the structure. That phenomenon is similar to the reason why some diamond honing plates are not completely covered on the whole surface and have some gaps between the abrasive areas to allow loose, rough particles too escape.
In practice, every compound is more or less contaminated with larger and smaller particles. The grit rating refers to an average of the final product. That is why I prefer materials that are somewhat able to filter/compensate for such variations due to their surface structure and/or specific hardness that should not be too hard.

One thing one could try is breaking the glazy top of the MDF with some fine sand paper to open up the surface just a bit and allow it to gain some of those properties.
That said, the surface is probably going to break in by itself over time by simply stropping on it. Also, not every MDF is created equal. The stuff I got from my local hardware store has a pretty resilient coating. But your results may vary.

Cheers!
 
What i always do is provide a thin plastic bag with each of these diamond paste coated MDF strops.

I also clean & reapply the diamond compound from time to time on strops in use with various Chefs when they bring in their knives for sharpening.

And some of these strops have been in use for 6-8 years now, and keep working satisfactory i'm told.

These smooth MDF strops have been found to work great for maintaining a keen edge on especially hard & wear resistant steel types for longer periods, and also provide for a better edge than ceramic rods.

The discriminating Chefs in my area mostly use knives in R2/SG2 steel for their balanced set of properties.

Especially knives made by Takamura and Shibata are very well regarded here.
 
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