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Is this a coti?

I see yellow coti's that sometimes have a brownish look to them (not tile) on one side that kinda looks almost purplish and I wonder if thats what this is. This stone is pretty smooth and mounted on something very coarse but it has very little specs of white all through it. It makes quite a slurry when I run it on 400 grit paper and water.It reminds me of a very hard piece of chalk. This piece is broken on one end but measures 2x4.5 inches on the shortest side and its 7/8" thick. Could someone help me identify it please? I am new to this. Thanks very much. Scott
 
Hi, I am pretty new too, but this does not look like a coticule, they are all yellowish. It might be a Belgian blue, but what color is your slurry? The BBW has a distinctive purplish slurry. Also, I have a Belgian combo stone and neither side feels chalky to me. The expert will weigh in soon, but I hope this helps.
 
Looks as if it could be a BBW (belgian blue stone), sometimes glued to the underside of a coticule and more rarely as a natural combination of the two. If it is one, the whitish dots are coticule material, meaning that the BBW will be a fast cutting stone (most are slow to medium) with a finer finish than normal (for instance if you said a normal bbw was 4000 grit, than one with these spots would be 5000 or higher, depending on the concentration of the dots).

Regards,
Neil
 
You need to look at a few threads on honing progressions and hone types/use. Depending on the perceived grit rating, maybe an 8,000 grit followed by a 10,000, 12,000 or 16,000 grit stone. There are many makes but you want to decide whether to stay to mainly mnatural stones or man-made.

A yellow coticule might be a sound next step as it can perform the tasks of several stones, depending on how hard it is (soft ones cut faster, hard ones finish better) and how thick a slurry you make.

Regards,
Neil
 
That's a low grit synthetic. Probably Carborundum.

The rough side would be useful for removing chips and the finer side maybe for setting a bevel. Sorry to disappoint. I own one of the brownest Coti's I've ever seen and it's really more of an orange than a brown. BBW's sometimes take a brown note when covered with oil residue, but the extremely rough backing grit is a dead giveaway that your stone is a synth. There are no natural stones that coarse that are used for hones (that looks like a Carborundum "Coarse" or about 80 to 200grit), and I've never seen a synth hone backing a natural one (though they may exist, I doubt coticules would be the stones they'd do it with)... and BBW don't need backing. They are used to back Coti's. If you ever found a BBW hone it'd almost certainly be attached to a coticule or else be alone.


If you asked for a wild guess I'd say it's a Carbo Coarse/Fine so ~150grit on the rough side and 600-1500 on the fine side.
 
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I'd recommend buying a modern "Unusable schist" backed ardennes stone (from them or a reseller , if you're in the USA, resellers tend to be a couple bucks cheaper but I BELIEVE you can ask for a natural combo from them at no extra charge if you go that route You'd just have to make the request in your order notes. No guarantee's though.) in 150x40mm.
You can get vintage coti's on eBay a hair cheaper than that, but the cost of a slurry stone or DMT to slurry with winds up making it more expensive in the end in most cases.

Expect to spend in the area of $70-80
 
I reckon you are right Ian - I didn't notice that joint!

Regards,
Neil

That's a low grit synthetic. Probably Carborundum.

The rough side would be useful for removing chips and the finer side maybe for setting a bevel. Sorry to disappoint. I own one of the brownest Coti's I've ever seen and it's really more of an orange than a brown. BBW's sometimes take a brown note when covered with oil residue, but the extremely rough backing grit is a dead giveaway that your stone is a synth. There are no natural stones that coarse that are used for hones (that looks like a Carborundum "Coarse" or about 80 to 200grit), and I've never seen a synth hone backing a natural one (though they may exist, I doubt coticules would be the stones they'd do it with)... and BBW don't need backing. They are used to back Coti's. If you ever found a BBW hone it'd almost certainly be attached to a coticule or else be alone.


If you asked for a wild guess I'd say it's a Carbo Coarse/Fine so ~150grit on the rough side and 600-1500 on the fine side.
 
Ian, a keen eye and a good shot, my friend.

Because I know you'll like it, here a picture of a Coticule. A brown one...

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It's an oxidized La Grosse Blanche. They slowly tan when hit by sunlight. This one's been to the beach. :001_smile
After raising slurry a couple of times it will be the usual pale color again. It still need to find out if the oxidized state has any influence on its finishing properties. What do you think?

Kind regards,
Bart.
 
Man that is a sweet looking coti Bart!

If I saw that in an auction I more than likely would pass it over as definitely not being a coti.
 
Ian, a keen eye and a good shot, my friend.

Because I know you'll like it, here a picture of a Coticule. A brown one...

proxy.php


It's an oxidized La Grosse Blanche. They slowly tan when hit by sunlight. This one's been to the beach. :001_smile
After raising slurry a couple of times it will be the usual pale color again. It still need to find out if the oxidized state has any influence on its finishing properties. What do you think?

Kind regards,
Bart.

Niiice. I think I might have a La Grosse, I'll have to leave it in the sun. About how long do you think they take to get a tan?
 
Niiice. I think I might have a La Grosse, I'll have to leave it in the sun. About how long do you think they take to get a tan?
Depends on the exposure. In direct sunlight, it's a matter of a couple of weeks to turn that brown. Indoors, it takes months, in a drawer I think even years. You can see that other stones were lying on top of this one for some time.

Bart.
 
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