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Brown Powder AKA "Cocoa Powder"


BlastFromThePast

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I was doing some reading and came across cocoa powder, which is BP that employs straw charcoal. Apparently it was created way back when, in the 1800's at some point. I find variations of BP very interesting such as golden powder (vitamin C). I know that golden powder isn't a BP variation per say because it's a completely different comp, but I'm speaking about things within the realm of BP. So as for this "cocoa powder", I know that it seems like a variation, similar to using pine vs willow charcoal, but it seems like it's something else altogether. I'm wondering if anyone knows or has heard about this before, or even tried it? Opinions, advice, or any other input is greatly appreciated. Thanks

Blast

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Never seen any, but I'm not sure I want to. COPAE and others regard it as very sensitive and not as stable as BP with willow or pine.

 

However in it's day it was probably an essential substitute for proper BP

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From what I've read, it was traditionally made from wheat straw. Is it safe to say that any type of "straw" based charcoal should be avoided. The only upside I could see from making charcoal from straw would be it's ease of processing, although it would most likely make for a low yield.
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I made some back in the day, using rye or wheat charcoal, can't remember which, but I was from the neighbors field. Took it out to beat and grind on it, seeing if this charcoal magically made it more sensitive...it didn't. I have no idea why the notes for sensitivity are there, but then again, it's from the 1800s?
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Silica, some straws and grasses once charred can yield as much as 25% silica. I think this is the problem.

 

Dan.

Edited by dan999ification
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And it would be the friction between the particles of silica that would allegedly increase the sensitivity of comp..? On a side note, if it really doesn't increase the sensitivity, then wouldn't this comp make for a better prime than BP considering the molten silica slag?
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BP doesn't melt silica. Otherwise we could just add sand to our primes and never have any problems. BP will ignite silicon though, which in turn makes molten silica.

 

Silica in the charcoal could certainly play a factor, but I don't know if it's really it. Even the granules are alleged to be sensitive. Silica wouldn't make a ton of sense for this property.

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Could straw charcoal be acidic, but even if it was--I don't see how it could make any sort of difference unless it was very very strongly acidic. Maybe there is/was a tendency for grit to contaminate the straw.
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I have been reading about both pyrotechnic black powder and black "gun" powder for several months now.

 

In general writers writing about old cannon talk about BP made from "brown" charcoal as having a slower burn rate and thus lower peak pressure, allowing for either heavy projectiles or lighter cannon, depending on the circumstances.

 

On the other hand pyrotechnicians talk about BP made from "brown" charcoal as burning faster becuase it still has some wood volatiles in it, suggesting it should be able to generate a higher peak pressure when used in field or naval artillery.

 

I have some brown charcoal still in lumps I haven't milled yet. I am going to wait until my process is consistent and giving me consistent results with black charcoal before I try to compare brown to black myself.

 

Fascinating topic, it is one of the great mysteries of BP to me. The wikipedia article on brown powder is here: http://en.wikipedia.org/wiki/Brown_powder

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  • 2 weeks later...

Cocoa powder was formulated to be slow, hence its usual abbreviation 'SBC' - slow burning cocoa. There was another variation called 'prism brown', which was a similar powder pressed into hexagonal prisms with a hole up the middle so that the burning area, hence rate of gas generation, stayed constant. It was only used in large caliber guns where the slow burn kept exerting pressure as the shell moved up the correspondingly long barrel. You can see what guns used what powder in this table from 1890:

 

post-10245-0-20896200-1369117313_thumb.jpg

 

Cocoa was obsolete almost as soon as it was developed. By 1900 all the ML guns were scrapped, and all the BLs except one used smokeless powder. The exception was the 16.25 inch Armstrong 110 ton gun, of which two were mounted in Gibraltar covering the straits. These were the most powerful weapons in the world at that time - 960 pounds of powder firing a shell weighing nearly a ton. They could fire clear across the straits and were so well sighted-in that they'd hit you from 10 miles away with the first shot (I posted a picture of the 110 ton gun in this thread). By 1910 these were gone too, replaced by 12 inch smokeless powder guns that had 50% more muzzle velocity and 25% more penetrating power from a projectile half the weight, and four times the rate of fire.

 

I've read several times that cocoa was a bit sensitive, yet I can't find any contemporary records of accidents while it was in use. The Lyddite (picric acid) shell filling used at the time was orders of magnitude more sensitive and dangerous. If it should leak out of a shell and come in contact with any lead or brass, seldom did anyone live to report it.

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