I’ve been sharpening for a bit now, and after some time got into writing this blog, because I was curious what the abrasives we all are using are made out of.

After a while, I decided to make my own design of stones. The motivation behind this was to undertake an adventure of science and create a stone that suits my style of sharpening better than what is available on the market. Because there’s a lot of questions about these stones, and the blog has grown massively, I thought I’d do a “FAQ” style page about my own stones.

Let me start with the most important one:

Are your reviews biased because you want to sell your own stones?

Honestly: I don’t think there is any review without bias. People have been asking me to put my subjective opinion about the sharpening action into the blog posts. Something I consider worth mentioning is that I honestly only do the stone business as a hobby. I have a dayjob, and I love that one. So whether you buy my stones or not, changes nothing about this blog. And I am first and foremost a scientist: show me something cool and new, and I am going to be excited and love it. There’s a couple of stones on this blog that I loved – and regularly use! So I can promise you this: If I ever review a resin stone that I like more than my own stones – e.g. that gives better results – I’ll state so very honestly on this blog!

Which stone set should I buy?

I believe the medium set is a fantastic starting point. You can start using this one after setting the bevel with most EP stones, and it will refine the apex and give you a nice gloss on the surface of the bevel. I regularly get sub-90 bess readings from this one without stropping, and the bevels look fantastic. I think this is the set everyone should start with. If you prefer a “toothy” edge, the coarse set is the one to start with. It gives you a nice, toothy edge, with a very fine apex and already a good level of gloss on the bevel! The fine set I really can only recommend to those searching for that last bit of mirror and sharpness – it really makes a bevel pop, but I wouldn’t start on it.

What makes your stones scientific?

These stones are developed through the scientific method. This means, I developed certain theories about how material removal and sharpening works, and then set out with experiments to proof this. The development process to get to this product was not based on “feelings”, but hard facts: Every step was meticulously analysed. I employ techniques such as DoE (Design of Experiments), double blind trials and fancy metrology techniques such as scanning electron microscopy, white light interferometers and high resolution optical microscopes to continuously make sure that the abrasive itself is improved instead of my skillset as a sharpener. Every iteration of these stones is improved through experiment, observation and conclusion – hence, scientific!

SEM Micrograph of the grain distribution inside the 2.5 µm Dr. Marv stone.

What is special about your stones?

The Dr. Marv stones have a very high concentration. I state it in weight instead of volume. But if you look at reviews of other stones on this blog, you will find that the industry standard “C100” concentration looks a lot less than my concentration. This means that these stones are fast cutting, and very long lasting.

The diamond is treated via a proprietary process to enhance the retention of the grain in the binder matrix. This process is secret (sorry, not gonna spill the sauce here!) but I engineered it down to an atomic level so that we get optimum retention: long lasting, but also self sharpening that the stones always perform at their optimum.

Finally, every batch is meticulously controlled via SEM. I throw away about 2/3 of the diamond I order, because it is not up to my standards. This shows in the grit distribution which I state for every order: The mean size is typically spot on, and the standard deviation is very tight – tighter than on commercially available products. The QC I do and production methods I employ also guarantee a contamination free result – there is no foreign grain in my stones!

The result is a stone that is technologically superior – it actually cuts through the steel, instead of rubbing, burnishing or smearing. What you are left with are better surfaces, a more refined apex and something I would consider a “perfect sharpening result” – even before stropping!

Flawless Cutting Edge in M398 after sharpening on the 2.5 µm Dr. Marv Stone

Why do you care so much about grit contamination?

You know those fine scratches, that sometimes appear just when you think you finally made that elusive perfect mirror finish? That’s because there’s a larger grain in your stone. I like my mirror edges shiny and perfect – thus I do everything I possibly can to avoid that contamination!

Industry standard: Large contamination particles inside fine stones (here: SiC (purple) and SiO2 (green) particles). These leave larger scratches than the fine diamond (red) does!

Are Dr. Marv’s Stones quicker than other stones on the market?

This is a difficult question to answer. I find their speed to be very high – especially considering the surface they leave. I think that they are significantly faster at reaching a certain surface – because the surface left behind is typically much better than you would expect from that grit size. So, a statement I would call very honestly is: They are about as fast as you would expect from their grit size, but the finish left is much better than you would typically expect from a stone of that grit size. If you doubt me, look at the reviews of my webshop.

Do they make my knife sharper?

I know people who can sharpen a blade to insane levels of sharpness on a brick. So no, I do not think you’ll automatically get a sharper blade. But because they actually cut, and not just burnish and rub, I believe it is much easier to get to sub-100 bess than it is with other stones. The final result is up to your skill – but as we all know, good tooling makes the journey much more pleasant!

Why are they so expensive?

With the layer of abrasive on these, I would say that they are actually very decently priced – considering you get > 4.5 mm of abrasive. Do the calculation yourself – you will see that “per mm”, they are very competitively priced.

And at the end of the day – this is a handmade product, produced in Germany, with most of the resources going into this also Made in Germany.