How to tell if you have a Coti Combo?

[Walker]

I recently scored a Coti on Ebay. The guy listed a few hones and listed them as a machinists hone lot (you may have seen my earlier post "is this a coti") upon recieving it i already had my slurry stone from SRP so i created my first slurry on it (i know, sweet right?). Just for fun i flipped it over and did the same to the back, it created a dark film or slurry on it too. Does this mean it is a BBW or does the slate that cottis are glued to also do it? I was instructed to use a DMT from another member to see if that creates the slurry also but my DMT won't be hear until Monday (that's a whole different can of worms) is there another way i can test it to see if it is a BBW? It's kind of a blueish or greyish film

 

[mainaman]

if its not natural combo the coti and the BBW are glued together and you can easily tell.
Nat combo has uneven line of contact between the two stones like this:

 

[Walker]

It's not a natural because the line is too straight and you can see a seem were it was glued ( or however they do it) together

 

[Walker]

Going through my Hone collection again tonight I found a small Norton Diamond Hone and I tried to raise a slurry with that. This is what I got.

View attachment 116661

View attachment 116662

View attachment 116663

View attachment 116664

I tried different settings on my camera to capture the true color of it. Maybe this will help. The little Norton I used is what you see between my fingers with the Coti.

 

[Walker]

Is there a Coti/BBW user online that can help me with this?

 

[mainaman]

if you have BBW it will be dark blue (according to some) purplish with darked dots to my eye. You can't mistaken it with slate, the slate is plain with no spots.

 

[Walker]

Ok, i didn't see any spots so it must not be a BBW. Thanx for the info.

 

[LessLemming]

This is obviously a BBW backing. No slate.
A No-slurry dry-wet picture would clarfiy it,
but I think I can tell from the slurry only pictures.

But that doesn´t mean you can use the bbw side.
It may have inclusions and be of bad quality.
You will have to find out for yourself (you wil notice, if the stone damages the blade)

 

[Woodash]

Ok, i didn't see any spots so it must not be a BBW. Thanx for the info.

I can't tell anything from your pics, but the combo that was sold here recently (http://badgerandblade.com/vb/showthread.php?t=160733) has, I think, a nice example of what a BBW looks like (see pic 5). The surface almost looks 'textured' and it often has a kind of a parallel, or subparallel arrangement of grains (may be tough to see with the naked eye). Sometimes has a kind of a 'silky' look or sheen or luster to it. Hey, that's the best I can do. Look up 'phyllitic texture' for more info.

Here's a pic of one showing this ~parallel striations running NE-SW, and some coti inclusions.

Anyway, good luck.

 

[Walker]

Thanx guys, excellent advice!!

 

[danjared]

I've seen BBW come from light purple to deep dark purple/blue, but the slate I've seen is darker. Based on your pictures and the second one from the auction, I think it's a BBW (or plain Belgian blue stone). If it's a vintage hone, that's another reason to believe it's a combo, as I believe the use of slate backing is an Ardennes thing. But if you want to be really sure, look at the backing under a good, strong light (not incandescent, which has a yellowish spectrum, and preferably just go outside at midday). The backing is Belgian blue stone if it looks at all purple-ish and especially if you can see little glittery specks (from the garnets). However, note that not all Belgian blue is suitable for use as a Belgian blue _whetstone_. It's possible to have a Belgian blue backing that is not suitable for use on razors. I've had one natural combo like that. So really, your best bet is to test it out. If you get good results, then you have a BBW. If you don't, you don't have a BBW or your honing methods sucks!

 

[Walker]

I'm sure my honing sucks since I have never done it yet.lol Here are some more pics I took outside today. I probably will never use the BBW side since I have my Nortons but i just wanted to know what I have here. He advertised the stones as a Vintage Lot of Machinists Hones. I don't think he knew one was a Coti because he mentioned one is a Norton and that was it.

View attachment 116739

View attachment 116740

View attachment 116741

View attachment 116742

View attachment 116743

 

[danjared]

Yeah, that's definitely not slate. It's worth giving it a try sometime. Also, it's tiny! It would make a good barber hone, maybe? I imagine that half-strokes will be your friend with that combo given the size.

 

[Walker]

Yea, I thought by the pics it would be bigger. It is just a hair under 4" X 2"

 

[dancraig]

If you can look at it under a hand held microscope, I have 30X, you will instantly see the little red/brown garnets all through the BBW.

 

[Bart]

If it's bonded (naturally or glued) to a Coticule and it produces a purplish/reddish slurry, it's a BBW.
The slate backing used on more recent production (approx. the last 20 years) produces a neutral light gray slurry.

Kind regards,
Bart.

 

[Walker]

Thanks Bart, it produces a purplish slurry. A few of the guys over at SRP seem sure it is a BBW so it looks like i did ok with that purchase. I haven't tried the BBW but the coti side really put a great edge on one of straights