Charcoals in BP

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richardh08
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Charcoals in BP

Post by richardh08 »

Here are the initial findings from my charcoal trials:
http://www.pyrobin.com/files/An%20Inves ... n%20BP.pdf
Comments and suggestions are welcome.
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Niall
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Re: Charcoals in BP

Post by Niall »

Excellent, have only had chance to skim this whilst at work, going back to read it tonight!

Will PM you too!
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Re: Charcoals in BP

Post by Pyro-Gear »

Good work Richard! I have a device for the next stage of testing on paper IE gas production it should work fine basically .5 of gram is used and a capillary action is observed as water is incompressible it should give you an accurate measurement.
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Re: Charcoals in BP

Post by Nightsun »

Very interesting piece of work indeed. I always think though that correct milling and granulating is so important. I was impressed when I used to fire muzzle loaders that the size of the BP is critical to muzzle velocity and safety. Great post.
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Re: Charcoals in BP

Post by Pyro-Gear »

I agree to a point, the milling is strictly controlled for the tests but the tests are run on meal powder straight from the mill, granulation is a key part in ballistics but for now the tests will be based around powder straight from the mill, I think Richard has been conservative about the results to date but I am betting there is a clear winner regarding burn rate, I have yet to build the gas production machine to further quantify future results it could be a case of burn rate V’s gas production who knows.
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Re: Charcoals in BP

Post by richardh08 »

It's clear, from reading 19th C accounts, that granulation was very tightly controlled as part of the means of obtaining a consistent product. Grain size is indeed important, with different sizes being made for each intended use.
So far, I haven't granulated anything as I haven't yet come up with a sufficiently feasible (for me) and consistent means of running propellant tests. I have a few ideas and it's a task that is fairly high on my to-do list.
As far as I am concerned, this work isn't about winners and losers, but just an attempt to learn more about the topic. It's true that there are 2 or 3 results that stand out, but no one sample is best in both linear and mass burn rates, and their differences from the best fit curve are only just over twice the standard deviation, so I'd be cautious about claiming they are significantly better.
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Re: Charcoals in BP

Post by richardh08 »

"I have a device for the next stage of testing on paper IE gas production"
I'm interested! It sounds as though it might turn out to be a useful additional means of comparison.
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Re: Charcoals in BP

Post by coalman »

That's a nice piece of work. It was particularly interesting to see the range of charcoal densities and their impact. I'm guessing it should be possible to develop a nice little model to plug the physical parameters into ... Multifactorial analysis? It would probably need more results but ...
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Re: Charcoals in BP

Post by richardh08 »

Yes, the relationship between burn speed and density was a bit of a surprise to me, too. Before I started, Ken was sure such a relationship existed, and I've heard the same opinion from one or two other sources, but I really wasn't expecting such a good straight line fit, with relatively little scatter.
I'm not exactly a genius at statistics, and multifactorial analysis is a bit beyond my mathematical skills, but I have to say that I had wondered how much of the scatter might be down to the interplay between the different factors and how much might just be errm... scatter.
At the moment I'm playing with the time-related data, trying to make sense of the way that the measured burn speed varies with milling time. I seem to be getting some more surprising results, some of which I partially understand and others that I don't.
I'll write another report once I've got my findings organised, but in the meantime I've got to go and mow the lawn...
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Re: Charcoals in BP

Post by Niall »

Richard said: "I'll name them if you want me to ;)"

I'd be interested to know these charcoals in question!
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Re: Charcoals in BP

Post by Pyro-Gear »

I have just ran a few tests with my new gas production device and found some interesting results, I only had three samples of BP to test Vine/willow/cat wood, take a guess what one came out tops!
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Re: Charcoals in BP

Post by coalman »

Let me get this right. Ash content includes water or not? You didn't say anything about drying before heating. If so the true ash content is [hydrated ash]-[water]. Admittedly the ash is probably hygroscopic so it could be bound water but still ...

It would be really interesting to see what happens if you acid wash the charcoal to remove as much real ash as possible and then get it as dry as possible before testing. Where does that end of the curve go?
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Re: Charcoals in BP

Post by richardh08 »

This is going too fast for me! At least I got the grass cut :D

I'll try to respond to all the points so far:

1) The top 3 charcoals were Acacia (Ken's 'cat'), Balsa and one of my four different samples of Willow. The last two were supplied by Niall. In terms of linear speed, the order was; first Niall's 'select' willow, closely followed by the 'cat' and then the balsa. For burn rates in g/s, the winner was the 'cat', again closely followed by balsa and then the willow. There really isn't much to choose between them. I don't want anyone to take these results as meaning that these are the three best species for making charcoal, as the remainder of my results indicate that species alone isn't a sufficient indicator.

2) If you force me to guess, I'd have to say the 'cat' produced most gas - but I'm quite prepared to be wrong. From my point of view, the really significant fact is that we now have a means of making this measurement. I'm delighted by this news.

3) The 'ash' measurements I made were on undried charcoals, calculated as:
(ash weight)/(weight of charcoal + adsorbed water) * 100%
I measured water content separately, as:
(1 - (dried charcoal weight)/(weight of charcoal + adsorbed water)) * 100%
In both cases the weights were measured immediately after heating, before the products had time to absorb any significant amount of water.

4) I also thought about the possibility of washing the charcoal but haven't followed it up. As all the charcoals I used were made by the retort process, it's unlikely that they will have much in the way of 'pure' ash mixed with them. I don't know enough about the chemistry of charcoal to be absolutely certain, but I would guess that at least some of the mineral content would still be chemically combined with other substances. I'd be prepared to bet that if you acid washed one of these charcoals before burning it, you'd still get acid-soluble products in the remaining ash. I'm also fairly certain that very little of the adsorbed water content is caused by hygroscopic chemicals in the ash (I still have the ash left from my last trial so I can check on this - I'll let you know if I'm wrong).
Your thought about washing and then thoroughly drying a charcoal before running it through the tests has merit but, I won't be trying it as it would be very time-consuming and I can't think of any easy way to prevent water being taken up throughout the milling and testing procedures (which take 2 to 3 days to complete).
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Re: Charcoals in BP

Post by Pyro-Gear »

Ok my initial results today regarding gas production.
The basic machine uses ¼ of a gram of BP this is contained in a brass breach that on ignition act’s on a medical syringe full of water, the resulting action creates a discharge through a capillary tube and is monitored as a rising effect against a tape measure to within .5 of a mm.
Results.
Vine 22.5mm
Willow (weeping) 25.5
Knot weed 27
Cat wood 28.5
Commercial Goex 24
Pine 23.75
Re cooked BBQ charcoal 20.75.
Interesting?
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Re: Charcoals in BP

Post by richardh08 »

That's very interesting indeed.

I've just taken some of those figures and matched them as best as I could to my own data:

Bearing in mind that there is only a partial match between your and my charcoal samples, I think the correlation is remarkable.

Oops, got the units wrong on the Y-axis label, but that doesn't affect the relationship.
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Re: Charcoals in BP

Post by richardh08 »

Here's part two of the analysis of my BP trials: http://www.pyrobin.com/files/Milling%20BP.pdf
This time, it's more about the milling process than the product. There's one result that I really don't understand.
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Re: Charcoals in BP

Post by Pyro-Gear »

There certainly is some very interesting data there and I will need to study it a little longer, but a couple of things I noted are the milling times seem to flat line I find that very interesting indeed as I have just tested some BP from a friend the wood was home cooked Alder, the mill used was a tumble bee from the states running 800grms of ceramic media milling time was 62hrs (cough)
Results.
Burn rate 30mm at 3.6 seconds.
Gas production 24.5.
Ok now I ran the same charcoal the same Kno3 and sulphur in my own mill for six hours today I used 20mm lead media the jar load was 1.9 kilos plus 100grm’s of composition.
Results.
Burn rate 3.2 seconds
Gas production 26.75
6hrs VS 62hrs?
My next point is yes the only time you will get real willow is if you make it yourself or pay through the nose from coats.
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Re: Charcoals in BP

Post by richardh08 »

Interesting figures: around 10% improvement in performance (on either measure) with 1/10th the milling time. I'm beginning to think your mill might be OK :lol:

I've just looked up the test figures for my own home-cooked alder: 2.50 sec for a 30mm burn, reached after a milling time of around 3 hours - milled in a P-G mill, of course!

It's not a competition. These figures just add further evidence to my belief that the species of the wood isn't sufficient to determine performance.
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Re: Charcoals in BP

Post by Pyro-Gear »

[quote="richardh08"]
I think your mill might be OK :lol: keep hold of it given the current climate i wont be making any more by the way the tumble bee burnt out around an hour ago so he has mine now! oh well such is life :lol:
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Re: Charcoals in BP

Post by coalman »

richardh08 wrote: These figures just add further evidence to my belief that the species of the wood isn't sufficient to determine performance.
Well, that's for sure. What have we got assuming nothing is standardised?
  • Milling time
  • Mill efficiency
  • Ash content and composition
  • Moisture content
One thing most amateurs (and maybe professionals) get wrong is confusing species with genus. People talk about pine as though it's a species. It's not and there are big differences between species. Scots pine (Pinus sylvestris) wood is quite different from Parana pine (Araucaria angustifolia) which isn't even a pine - it's related to the money puzzle tree
!
Then there must be biological elements to do with wood formation - seasonal growth, shading, rainfall, soil type and fertility.
I'd like to see some classification of woods by structure to see whether that is a predictor too - xylem vessel diameters, density, gum/resin content and probably plenty more. There must be loads of untested woody species and wouldn't it be great if you could just check structure with a magnifying glass and density?

I'd also like to know whether different methods of milling have an impact - what makes fluffy charcoal? Is it just the structure?
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Re: Charcoals in BP

Post by richardh08 »

You make some valid points there.

The trouble with most comparative studies of charcoals is that they all use different techniques, so it's impossible to compare one with another. There is one report, for example, that did something similar to my trials, but pre-milled the separate ingredients for 12 hours (!) each and then milled them together for a fixed period of one hour. Not surprisingly, the results showed so much scatter that a pattern didn't emerge. I looked at my data after one hour's milling and the results were not particularly compelling. Even at two hours, it was difficult to see a trend. By milling until there was no further improvement in performance, I hope to have removed at least one arbitrary factor.

I've seen at least one study that made structural measures, including porosity and electron microscope images, in an attempt to determine what made a 'good' charcoal but I don't think the results they obtained have any predictive value.

As an illustration of how 'professionals' can get things wrong, that same study stated that they found that the carbonisation process had to be extremely closely controlled. They based that conclusion on a previous study (by someone else) that showed the best performance came from a carbon content of around 72% (not incompatible with my results). They then found that their wood samples passed through that percentage on a steep curve during carbonisation and that it was therefore difficult to stop it at exactly the right point. However, since they didn't actually make any BP to test their conclusions, there is no way of knowing whether or not their 'careful' carbonisation produced optimal performance. A bit of a case of putting the cart before the horse, I feel.

I'm fairly sure that 'fluffiness' is more to do with the charcoal itself than any milling history. I have plans to try and untangle some of the effects of different milling techniques, and I'll report on my findings. Don't hold your breath, though, as it will take quite some time to complete.
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Re: Charcoals in BP

Post by Niall »

I'm looking forward to an unadulterated read of these tonight on my way back, so far I have read them during breaks and moments but not had chance to ADSORB them.

Little play on words just there. I'm finally getting back in the seat, rocketry is looking promising this week!
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Re: Charcoals in BP

Post by richardh08 »

Here, at last, is my report on the ballistic testing: http://www.pyrobin.com/files/BallisticP ... ceOfBP.pdf.

I hope it was worth the wait!
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Re: Charcoals in BP

Post by Tyvole »

It was certainly worth the wait, Richard. The final conclusions regarding density vs performance are perhaps not so surprising but you are to be applauded for the careful and methodical manner by which you have arrived at them. This examination of the differences between charcoals has been both fascinating and revealing. I'm sure that anyone who takes the time to read and understand what you have done here will henceforth pay much more attention to the pedigree of their BP charcoal, perhaps even deciding that it really is worth making one's own from known source-wood. Many thanks, Richard, for your considerable efforts over an extended period and your willingness to freely share the results with us.
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Re: Charcoals in BP

Post by Starfire »

Thanks good work Richard.
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Re: Charcoals in BP

Post by Pyro-Gear »

Excellent piece of work I must say and I am sure this PDF will make its way in to a book one day, now who was it that said BBQ charcoal was cooked to death!
I had a feeling Cat wood would be a winner having very long open fibers in the structure of the wood it all added up well to me it did, the unknown willow well it does not leave much to the imagination!
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Re: Charcoals in BP

Post by Boophoenix »

Interesting thread from the past.

In particular Coalman's post above covered some curiousities I've had over time. Hopefully I can research some of this in the upcoming adventure.

Richard, very valid point on all the different vairibles. Let's hope I can meet the standards from the testing that y'all have done in my adventure. Although some fields I'm going to tinker with will be additional and some methods will be different I'll do duplicate testing if I change anything from the standard. I've ordered a mill to to use so we take that vairible out even though some of my testing will be done in the two models of mills I currently have. Hopefully by having one of Ken's mills I can find a common vairible and the result from all of the mills can be used. Somewhere along the line there has to be a commonality that can be found to make results useful across the board I hope anyway.

The big hope is that y'all don't bore of my questions trying to form the same methods and practices along the way. :D
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Re: Charcoals in BP

Post by Lloyd »

Bradley,
In this environment of "dyed-in-the-wool" experimenters, I doubt you'll bore anyone with your findings, even if some overlap older ones!

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Re: Charcoals in BP

Post by richardh08 »

I'm really looking forward to the time when you start to produce some results, Bradley. I realise that won't be soon; I'm well aware of how much time and effort it takes.

From my point of view, the really interesting stuff will come from what you plan to do in addition to the measurements I made, for example, the effect of using different mills. For a long time I have had a plan to look into the effect of using different types and amounts of milling media, but other projects keep getting in the way.

Don't worry about asking questions. I - and, I'm sure, several other people on the forum - will answer them if I/we can.

And to add to what Lloyd said, none of what you find will be boring. Even (or maybe especially) if some of your results echo previous findings, it will demonstrate that they are real, and not the imaginings of some poor demented soul!
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Re: Charcoals in BP

Post by Tyvole »

richardh08 wrote: Even (or maybe especially) if some of your results echo previous findings, it will demonstrate that they are real, and not the imaginings of some poor demented soul!
But, isn't that exactly what the 'scientific method' is all about? Confirmation or falsification of the findings of others? You chaps are not simply playing at pyro. You are doing proper science. I might even venture to say, rocket science! :D
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