BRKT black compound grit size?

awestib

awestib

Joined
Dec 29, 2008
Messages
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I know that has been discussed a lot and we have the grand unified grit chart etc. Based on that chart, the black compound from Bark River Knife and Tool is 4 microns. Other sources give me a range of 1200 - 5000 grit?? Fortunately HeavyHanded has analyzed a few compounds and came up with quite a reliable range of grit in a given compound but I don't think the black one.

Different black compounds have different grit size and it depends on what surface you use and whether the particles brake down and fracture easily or not.

Today I took a 440c kitchen knife and sharpened one side on a slightly used DMT green plate (based on DMT's website that is 9 micron) without !! water. The other side on HeavyHanded's washboard with one page of printer paper and BRKT black compound with a touch of oil. Now I only have a 20 x lupe but I am quite certain that the black compound produced a coarser scratch pattern than the green DMT stone. In fact the scratch pattern looked very similar to the DMT red stone which is supposed to be 25 micron (although mine is a well used one!).

I would like to hear some experience with the BRKT black compound from you guys in regards to scratch pattern, coarseness etc.
 
If you send me some I can tell you with a bit of confidence what's in it. How does the scratch pattern look if you swap the paper on the Washboard for something with a flat backing - a Spyderco ceramic stone or similar as an underlay?
 
Ken Schwartz works closely with BRKT and now sellls some CBN under their label.

He has used the black stuff extensively and iirc he mentioned to me one time that it is slightly coarser than the 4u CBN. Putting it in the 2500-3000 grit range.

As with any stick compound of an unknown abrasive type and particle size distribution this can vary (sometimes widely) from batch to batch. Although I am given to understand that the BRKT stuff is the most consistant , it still wont hold a candle to a high quality preperation.
 
HeavyHanded said:
If you send me some I can tell you with a bit of confidence what's in it. How does the scratch pattern look if you swap the paper on the Washboard for something with a flat backing - a Spyderco ceramic stone or similar as an underlay?
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I think I know what you mean Martin, the washboard surface makes it a bit more aggressive than it would be on a flat surface! Will try out. Thanks for the offer! I may be able to send you some this week. Can you send me your address (again?) to awestib at me dot com? Thanks!

Sadden said:
Ken Schwartz works closely with BRKT and now sellls some CBN under their label.

He has used the black stuff extensively and iirc he mentioned to me one time that it is slightly coarser than the 4u CBN. Putting it in the 2500-3000 grit range.

As with any stick compound of an unknown abrasive type and particle size distribution this can vary (sometimes widely) from batch to batch. Although I am given to understand that the BRKT stuff is the most consistant , it still wont hold a candle to a high quality preperation.
Click to expand...

Thanks Sadden, I can not believe that the black compound is that "fine", it does not feel that fine to touch when applied, not even on a surface with some give, denim for instance. I have some experience with the CBN 16 micron (1000 grit) on very thin leather and I am not even sure that this is coarser than the black compound ?! I think the black is somewhere around 14-15 microns??

Thanks guys for the reply!
 
I have used the black compound and of course my CBN compounds and even tried to analyze the black compound. Among 'black compound bars' in my experience it is a consistent product. I was unsuccessful directly analyzing the black compound directly for technical reasons, but have done comparisons of the scratch patterns it produces. It is coarser than 4 microns and not as coarse as 8 microns.

I am in the process of coming out with compound bars that, unlike anything else out there on the market, are designed to handle abrasion resistant steels as well as 'regular steels'. These will be in the range spanning 0.5 microns up to 80 microns for the initial product release. NONE of the compound bars out there are anywhere close to even having a precise specification of their product let alone a product like this. I am targeting this product towards knifemakers who use buffers for producing finishes both on their edges and the entire blades. Initial testing even with steels like k390 are resulting in spectacular mirror finishes.

---
Ken
 
ksskss said:
I have used the black compound and of course my CBN compounds and even tried to analyze the black compound. Among 'black compound bars' in my experience it is a consistent product. I was unsuccessful directly analyzing the black compound directly for technical reasons, but have done comparisons of the scratch patterns it produces. It is coarser than 4 microns and not as coarse as 8 microns.

I am in the process of coming out with compound bars that, unlike anything else out there on the market, are designed to handle abrasion resistant steels as well as 'regular steels'. These will be in the range spanning 0.5 microns up to 80 microns for the initial product release. NONE of the compound bars out there are anywhere close to even having a precise specification of their product let alone a product like this. I am targeting this product towards knifemakers who use buffers for producing finishes both on their edges and the entire blades. Initial testing even with steels like k390 are resulting in spectacular mirror finishes.

---
Ken
Click to expand...

That sounds awesome Ken! Will it be suitable for strops as well and will it be available for "normal" customers?
 
"That sounds awesome Ken! Will it be suitable for strops as well and will it be available for "normal" customers? "

Yes, normal customers can certainly purchase it. Of course I consider all my customers 'special' - in the most positive sense of the word. I have formulations that are already optimal for leather strops, nanocloth, linen belts etc that would work better than these. i will be trying these formulations on things other than buffing wheels too - just to better know how well it will work in other circumstances.

These formulations specifically addresses the issue of sticking well to a 10" buffing wheel (or smaller) made of cotton or sisal spinning at 3700 rpm or slower and staying on rather than flying off. Not an easy thing and even the commercial compounds already out there aren't that good about this requirement. I've done the initial testing going through a number of iterations until I got this formulation which is optimized. I JUST got some of them in (when I came in the door this evening) and yes I'm excited!!! Of course I'm always my own first customer, since if something is going to crash and burn, I want it to happen to me rather than my customers. More to follow, but if you want more info in the mean time, contact me anytime. Most people other than knifemakers don't have buffers, so that's why I mention that this product line is targeted at knifemakers who want to up their games with finer finishes both on their edges and their entire blades.

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Ken
 
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