Hard vintage synthetic for knife sharpening

[*stefan*]

What are your experience regarding really hard synthetic stones for knife sharpening or honing straight razors?

I got a hard synthetic sharpening stones, probably synthetic that I really like to use if I
only want to sharpen one knife.

This stones cover a width range of grit like 220# to 5000# for me.
Work with running water and don’t seem to clog.
Very compact stones and probably presoaked in something. My hands get greasy with grey color reminding me of grease from fishing reel gear.

I like softer synthetic water stones too that often needs soaking if honing 3-5 knifes. But having the option to just use one stone is nice.

Picture show this stone, extremely hard and I needed diamond plate for lapping, sanding paper didn’t work (80# and 120# tested).
The smaller stone is very similar in grit and behavior but it’s a little bit softer.

The orange I suspect is al-oxide, give edge like 2000# and is very hard. This stone seems to clog but cuts anyway so far with just water.
Looks wise it reminds of the small India-stone (that I have not yet tested).

I have had other synthetic that just clog immediately and don’t really cut. Why I was surprised with this 2 stones.

 

[kcb5150]

Old india oilstones and carborundums work really well. They really are pure oilstones though.

 

[*stefan*]

Have actually never tested sharpening or honing with oil.
Need to get some and test.

 

[buca3152]

I have the venev diamond bonded stones. They work very well on very hard steels but they load up quickly on carbon steel.

 

[Toro Blanco]

Two of the hardest stones I have and have ever encountered are a pike labeled India stone and even harder Pike or Carborundum SIC two sided hand poured stone. They cut very nicely and can work way finer than the newer ones. The India is a little harder than a hard Ark and the SIC stone is crazy/insanely hard! Even with 80 SIC loose grit it took a very long time compared to a hard Ark. I used to think Arkansas stones were hard until I met one of those.
I still have it as I like to use them for knives when they have issues or chips.

 

[bluesman 7]

Have actually never tested sharpening or honing with oil.
Need to get some and test.

Or you could try water and polypropyleneglycol or Smith's Honing Solution. That's all I ever use on carbos and Washitas