Black Powder Thread #1

[pyrogeorge]

How many purity (%) must be the kno3??i think that to make good bp the kno3 must be pure..

is it right??

[oskarchem]

Well the more pure your chemicals are, the better performance you will get, but, KNO3 can be what about 94%

[pyrogeorge]

Freakydutchmen. Look at the FAQ in the rules and announcements section.

 

Pipipi, even granulating wont help that poor of BP. I've said this to you at least 3 or 4 times. You have a shitty ball mill. You have to mill significantly longer than 3 hours. You don't need to add dextrin, but it certainly helps the granules from crumbling and to stay a consistent size over time. You MUST use water to activate it. Alcohol will not do anything to dextrin. Solutions over 20% alcohol or so will significantly reduce the activation of dextrin.

i milled other 3 hours,totally 6 hours but the result is the same..i will make bp from newspaper charcoal and i will see the result

[justanotherpyro]

As I said, small granulations will perform slightly better than meal powder in my experience. However, corned powder will perform less effectively than both (also my experience) due to the decreased surface area (and thus slowed reaction rate) of the smooth grains resulting from breaking up a pressed chunk of composition. A flame front will propagate surprisingly quickly through unpressed meal powder made from ideal charcoal. Quickly enough to tear a polumna casing into 2 pieces.

Here are the results from my tests today. Meal BP vs corned BP. Both were from the same batch of BP. The meal was wet 10% by weight with 25:75 Isopopanol/water, pressed and corned through an 8 mesh screen. The grains were then screened through a 16 mesh screen and those that didn't pass through were the ones kept and used.

 

10g meal on the left, 10g corned on the right.

 

http://i42.photobucket.com/albums/e301/justanotherpyro/mealandcorned.jpg

 

Here are the videos.

Meal

Corned

 

Both were lit in a pile the same size as in the picture.My camera records at 30fps. The meal burned 26 frames or .867s

The corned burned 12 frames or .4s

I counted fames starting when there is the first sign of ignition and stopped when there was no visible flame.

 

It is counter intuitive that the corned burns faster but it does . There are more variables than just surface area. As mumbles said the loose meal acts as a single particle. There is not enough airspace between the particles for the flame to penetrate well enough and propagate properly. You are right that the corns have less total surface area and therefore burn slower. However, the air space in between them allows the corns to light simultaneously which not only makes up for the decreased surface area, it overpowers it. Each grain may burn slower but the overall burn time is reduced because they are all burning at the same time. Whereas the meal powder's individual particles do not burn simultaneously.

 

At this size the decreased surface area is trumped by the ability of the grains to all light at the same time. The question is at what point do the grains become to large that their ability to light simultaneously is not enough to compensate for their size and therefore cause a slower burn rate than meal?

[Canadian_Pyro]

Both piles appeared to burn pretty slowly to me, so I wouldn't call your results a definite conclusion.

[justanotherpyro]

Both piles appeared to burn pretty slowly to me, so I wouldn't call your results a definite conclusion.

The relative speed of the BP does not matter. The comparison is what the issue is. It wouldn't matter if I started out with green mix and then compared it to an equal portion of corned green mix. It wouldn't matter if it was the fastest BP known to mankind as long as the comparison was between meal and corned BP.

 

I think you need to watch them again if you think both burn slow. The meal does burn slow as that was exactly my point but the corned burned with a fast "thump". However, like I said the relative speed is irrelevant here. The comparison is equal piles of meal and corned had a burn time of .867s and .4s respectively. It wouldn't matter if it was 1.5s and .70s or even it was 100s and 45s. The point is is that the corned was more than 2x faster than the meal.

 

If you want to argue about a critical point at which the results may change, such as in a 1g increment that meal would perform the same, better or worse than corned BP, then be my guest but don't turn your nose up at fairly hard evidence that clearly backs up what I have said. You are right that it is not a definite conclusion. It can't be because there are to many variables. If we had 100g of quarter sized chunks of BP I doubt that they they would burn as fast as meal. This is purely speculation and I don't care to test it because it is impractical. But what is considered corning for lift powder and its comparison to meal from the exact same BP the results are clear and obvious.

[Canadian_Pyro]

The relative speed of the BP does not matter.

Don't you mean "The speed of the powder doesn't matter, so long as they are still relative?"

 

You seem to have missed the point, again. I have never stated nor implied that meal powder burns more rapidly than small granulations. The point is, when using very reactive charcoals, the difference is very small. I suspect that you are using some species of willow or other moderately reactive charcoal. Try balsa charcoal, I think you will be surprised when a few grams of meal blows apart your shell if it is not heavily reinforced. When you do manage to get a shell to leave in tact, the difference between the granulated and meal powder is usually statistically insignificant.

 

Your powder is roughly equivalent in burn rate to the result of my best attempt at the precipitation method of production. 10 grams of the best milled meal powder I have made burns in under .2 seconds. I'll try to find the video I used to obtain this value.

 

Your evidence backs up your statements as applied to your particular scenario. Nothing more. You cannot possibly expect to arrive at a universal conclusion with a single test, so don't act like you just did.

[justanotherpyro]

We'll start from the top. You failed to specify what sized grains you use for lift. If you are making pebble sized pieces then some things change. Second you stated

"Corning black powder by pressing it into a solid grain, then breaking up the grain into small fragments generally results in slower flame front propagation through the mass of reactants, and a reduction in overall burn rate."

Which I proved to you was incorrect. Flame propagation is enhanced because of space between the grains. The grains I'm referring to are very close to 2FA which is cannon grade powder!

 

Next you stated that there is only an increase in smaller grains, 40-50 mesh. I showed that in roughly 2FA mesh grains that there was a 200% increase.

 

You said that the more intimate mixing of KNO3 to the C particles is canceled out by dissolving the KNO3 particles already in the pores of the C. It is pretty widely accepted that wetting actually does increase burn rate via this mechanism. It is why CIA BP is even possible.

 

You failed to specify the size of grains that are considered big, so I went with what is considered cannon sized grains which I would consider fairly big.

 

As far as claiming a universal conclusion, I even said and agreed with you that there is no definite answer. I don't claim to have one. I merely presented the results testing your claim that corned powder generally will perform less effectively than smaller granulations (40-50mesh) and meal. I showed that what could easily be considered large grains, cannon grade 2FA, opposite to what you said had a 200% increase in speed. I know that there are varying results from varying powders, because it is the nature of the beast. All I did was test your statement that generally corned grains burn slower than meal or smaller grains (40-50) mesh. The results showed that not only did the large grains compare to the claimed 5% increase in smaller grains but that the larger supposedly slower burning grains trumped it with a 200% increase. Would you not call that significant?

 

It sounds like there are a few specific things that you are failing to mention and its a source of confusion / misunderstanding.

[TheSidewinder]

Gentlemen, this has been an interesting debate, and I encourage you to continue it. However, it's heading towards "argument" rather than "debate".

 

Let's keep this civil and analytical, please?

 

It's one of the things that seperates us from places like rec.pyro and we all know what tripe can be found there, eh?

 

Thank you!

[Inava876]

I'm new to this site. and new to making black powder. i've recently made some but its strange. it burns quick but isnt really working for things like Polumnas and Starmines. could anyone help me or give me advice on what to do?

[nath0r]

Is it granulated or just meal powder? If you are trying to use it as lift it will need to be granulated. I don't have much experience with Polumnas but as i understand it you need to use pulverone here also.

 

There are threads here on how to granulate black powder so if you havent already have a little browse through the tutorials section.

 

Hope this was of use, let us know how you get on

[aa92td]

Hello everybody.

i was thinking about someting , black powder ratios.

was ratios everyone here using and what charcoal for each ratios?

 

I will begin. KNO3;C;S

For pine charcoal i am using the regular ratios, 75 15 10.

For commercial hardwood charcoal i didnt found the best ratios yet.

when i am making blackpowder for stars i using 73 18 10

 

If someone here using commercial Hardwood charcoal and have a good ratios please post it and if you have any suggestions or differnt ratios that you using share it with us.

 

Sorry about my English , AgwA.

[frogy]

My freshly milled BP will burn in a similar manner to slow flash powder when unconfined, and shatter shells launched out of a mortar tube. I have to use large granulation sizes to make it usable for lift. Of course, I use a very reactive charcoal, so I am not terribly surprised.

Unless you are making your lift with holy water or having your BP blessed by the Pope then I doubt your lift is as good as it sounds. Like Mumbles said, construction techniques are probably the issue. Furthermore, corning lift makes it burn faster. Even very large pieces ( roughly gravel seize roughly 1 cm in diameter and thickness) of my BP burn lightning fast. So saying that you have to corn it to achieve a slower burn is counterintuitive.

Although I realize I'm responding to a fairly old post (Apr 24), I would like to throw in that I have also had some BP that burns very fast, towards the range of slow flash powder.

 

White Pine Granulated Lift (75:15:10, 3-6 hours (can't remember) with +5% dextrin bound with 25% alcohol (alcohol % a tad too high)).

http://youtube.com/watch?v=kngwO_Itlg8

 

 

To AgwA, I don't see why people would talk about which ratios they are using.... Unless they have found some crazy new ratio that works great, everyones black powder [meal] ratios are going to be 75:15:10 or near 75:15:10....

 

Meal: 75:15:10

Lift: 74:14:12

End Burners: 6:1:1 (75:12.5:12.5)

Core Burners: 6:3:1 (60:30:10)

 

Anything different will be someones pointless ratio tweak just to say that they use something different...

 

Charcoal based stars simply have a higher Charcoal ratio than regular black powder....

 

TT: 44:44:6

C6: 55:33:7

C8: 49:40:6

CoM: 45:50:0

[flying fish]

But is "slow flash" really that well defined? Some folks will use a lower grade of fine flake Al and call it slow. It still behaves like flash for all practical purposes, but is a little genteler on the stars. Then for other people, slow means that you use nitrate (and/or coarse Al) instead, bringing the speed down to (or in some cases below) the range of fast blackpowder.

 

Maybe I'm just rusty on pyro terminology, but is seems almost like saying "I caught a fish so big that it wouldn't fit in the boat," and then neglecting to say what kind of boat you were in (probably a Kayak )

[Swede]

Meal: 75:15:10

Lift: 74:14:12

End Burners: 6:1:1 (75:12.5:12.5)

Core Burners: 6:3:1 (60:30:10)

 

This is interesting - I'm not quite at that stage where I'm making separate batches yet. My last large BP batch was a standard 75:15:10 with willow, and I'm finding it's too fast for core burners by far. I'm getting too many CATOs, loud and spectacular ones.

 

I've left this hot batch as meal. Question - if my 4 ounce rocket takes 12 grams of fuel, is it possible to weigh out the 12 grams, and then, in a small cup, manually dilute it by stirring in enough airfloat to take it to 60:30:10? If so, I'd like to give it a try. I am using a hydraulic press and AFAIK am doing everything else right when it comes to pressing the fuel and nozzle.

[justanotherpyro]

You should be good to mix it in. Most likely you will end up with an orange tail from the rocket because you aren't ball milling but thats not a problem for rockets. Rather its a good and desirable effect.

[frogy]

Just mixing in extra charcoal is what most people do... Note that airfloat added like that is not going to be thoroughly incorporated, so you should add less than 1/5 more...

 

Most of the time people add -80 mesh charcoal to their meal in +5-10% amounts to slow it down and add nice spark trails.

[Mumbles]

That core burner ratio just screeed together normally as far as I know anyway. And yes, meal is far too hot and reactive for core burners.

[justanotherpyro]

Many people on the board use meal in their core burners IIRC. Actiontekjackson and myself included. For our rockets we use cowboy brand charcoal which isn't as reactive as willow or alder but it makes good meal.

[psyco_1322]

You could add a bit of petroleum jelly to your hot willow meal and it would keep the dust down a bit and slow your burn rate. Other wise I would not mill it at all, just use it as green meal. Possible add a bit of mineral oil or petroleum jelly to help with clean up.

 

All this talk makes me wanna pound out some 4ozers on my pointy spindle that makes nice hyped up rockets.

[Mumbles]

The petroleum jelly helps with the impact sensivitiy with strobe and whistle fuels. I don't know how much use it would be in BP. Most people will just wet and granulate the powder, sans binder. It achieves pretty much the same result with no solvent or mess petroleum jelly to work with.

 

If your green mixed powder is still too hot, adding some granular charcoal (start around 80 mesh) will be a good way to slow it down. Everyone's chemicals are different, and will take some tweaking. I know several people who use half and half airfloat and 80 mesh charcoal. I can't remember if it's 6:3:1 with half of the charcoal as 80 mesh, or 75:15:10 with an additional 15 parts coarse after ball milling. Either should work fairly well though, with the second being somewhat hotter.

[FrankRizzo]

I use ball milled 6:3:1 with half of the charcoal as ball milled Kingsford briquettes added in afterward. The sticks and bear turds make for a purdy tail.

[psyco_1322]

Guess that the petroleum jelly works good when ramming to compact a bit better, as does wax, but if pressing than it is just to much trouble just to reduce burn rates.

[Yankie]

I'm just curious as i have never seen anything about it but has anyone tried eucalyptus (gum tree) charcoal?

PS: made my first batch of balsa charcoal and omg is it light and fluffy, i had a container full of it and it weighed about 4 grams whereas a quater the volume of pine charcoal weighed around twice as much

[psyco_1322]

^Makes it last longer

 

I also have some coffee bean tree wood I want to cook and see how it performs. I picked it up after a lightning bolt blew it all over my yard.