NOS Thuringian inclusions?

I have never seen a vintage Thuringian, so I do not know what they look like up close. However, I believe that my NOS has inclusions, so I have included pics seeking assistance.

1. Brown spots. Looks like mud actually. Can't scratch them with fingernail. Also notice all the sparkly spots.

2. Darker spot in the center of the stone. The other side has these guys all over. They are very smooth and glassy. I just tried taking a picture of the other side, but I suck.

3. Bigger sparkly spots. Just a few of these. Better shot of all the sparklies though.

Thoughts on what they are or how they affect touch-ups?

thanks,
jeff

I have read in earlier threads that Tony Miller (Heirloom Strop Co) quit importing and selling Thuringans because he frequently received stones that had inclusions that made them unsuitable for honing.

I can't say from the photos whether what you have there would be a problem. If you have a dull blade give it some light strokes and see if you can feel the inclusions. Sometimes they are inconsequential.

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Originally Posted by JimmyHAD

I can't say from the photos whether what you have there would be a problem. If you have a dull blade give it some light strokes and see if you can feel the inclusions. Sometimes they are inconsequential.

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It does not feel perfectly smooth, but like it has little catches/grabs along the way. I just lapped it with 1K sandpaper. But I am super-noob, so not a reliable source.

cheers

As long as the inclusions are hard and not loose it should be ok. If they are loose they could come out leaving a pit or if they are soft like mica for instance they will wear out or may catch the edge as you hone.

+1 on what Thebigspendur writes about loose particles.

As an addition: the shiny gold bits would be pyrite, an iron sulfide. It's much softer than steel, so in theory wouldn't be harmful at all, but in practice can damage an edge if larger particles come loose.

The dark spots: I haven't found a Thuringian/Escher where honing is significantly hindered by this type of variation in the base material. Almost all my /Thuringians display these striations, flecks, wavy lines in some degree - and I like them all the more for it.

The brown spots: no idea; haven't seen that before.

One of my vintage thuringians has few brown/tan spots, and I'll be selling an escher or two of the same size and keep the one with the spots because I think it's a more interesting hone.
But in my case the performance is not affected negatively, which may or may not be the case with your stone. You'll have to find out by trying it out.

I have been selling these NOS Thruingians for quite a while now. The inclusions are fool's gold (pyrite). Pyrite is too soft to be a problem.

Unfortunately many of these come with hard inclusions as well that make them unsuitable. If you buy one make sure you agree that you can return it if you find it has one or more hard inclusions. I return about 1 in 3 to my wholesaler because of the hard inclusions.

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Originally Posted by Kees

Unfortunately many of these come with hard inclusions as well that make them unsuitable.

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How will I know which ones are hard?

thanks

If the pyrite is embedded in the stone's matrix solidly and is not released when honing or if the particles are extremely small, I would think you'd be fine. The only way to tell is hone razors and view the edge.

I once owned a Nakayama Asagi stone that had relatively large pyrite inclusions. Those inclusions DID release from the stone when honing and DID cause micro-chipping to the edge. The stone vendor, So Yamash.i.t.a readily took the stone back and promptly worked with me to find a replacement stone that was suitable to me.

Here are some pics from that stone that I returned:
Attachment 31163

Attachment 31164

Attachment 31165

Attachment 31166

I don't know if what you have there are pyrite inclusions or not. The only way to really tell would be to inspect the stone first hand and ideally under some form of magnification even low level magnification. You should see gold color.

Chris L

Hard inclusions can be felt. After handling many NOS Thuringians you get a feel. I usually lap them before shipping. After lapping them I run a razor across the lapped surface. After 2 strokes you just know whether it has hard inclusions.