School me on BP

[B2Crawler]

Please school me on BP

 

I see post after post about BP salute cannons, BP for lift charges, people talking about how they made their BP on a ball mill, BP this and that,

but what I am curious about is what is the difference in the grain size, what I mean is which grain sizes are better for what purposes?

For instance in consumer grade what would you use cannon grade for vs say FG2 for? vs. FG4 for?

 

Also what decides the burn rate? the grain size or?

 

I found this chart about the grain sizes but still not sure what applications would apply to these, this is just a comparison chart that show the difference between sporting grade and pro grade...

 

Black Powder Grades & Equivalent Sizes (in mm) Sporting Grades (G) Grain Size (in mm) Blasting Grades (A) Grain Size (in mm) 1FA 8.0-4.0 Cannon Grade 4.76-1.68 2FA 4.76-1.68 1FG 1.68-1.19 4FA 1.68-.84 2FG 1.19-.59 3FG .84-.29 5FA .84-.297 4FG .42-.15 7FA .42-.149 Meal D .42 5FG .149 Fine .149

Just curious wanting to learn more, mainly so when reading post or hearing someone talk about BP things then I know more about what they are doing with it or know what they are talking about.

Edited April 4, 2015 by B2Crawler

[schroedinger]

First welcome aboard.

 

Bp is generally divided into slo and hot types.

 

The slowest being scratch or green mix. Bp made just by sieving the indegredients together (some also count bp milled for only a short time, about 10 min, as green mix).

 

The hot types are made by milling all the chemicals together in a ball mill.

 

This fine mix can either be coated onto a inert carrier like rice hulls. This is done mainly for burst.

 

Also it is possible to rice or corn the bp.

Ricing is done by making the bp into a putty ball of bp and rubing it through a screen.

Corning is done by wetting the bp, pressing it into pucks and braking them up.

 

The last two methods are getting sized, into the sizes yoj listed above, using screens.

2FA, and FFg or 4FA are the main sizes needed. 2FA is needed for burst and filling voids in cylinder shells and lift in shells bigger above 4". FFg is used as a filler and Lift in shells to 4"

 

There are a lot more of variations where what is used, so only see it a a rough guide.

[Wiley]

Also, the "Fg" powders are sporting grades, and the "FA" powders are blasting grades. They are both black powder, but they use different scales for sizing, as you can see from that chart. 2FA is coarse and chunky, but 2Fg is pretty fine, at least for use in fireworks. The only real difference is that sporting powders are tumbled in graphite powder, which really doesn't affect the performance of the powder at all.

[FlaMtnBkr]

Fast BP is made by milling in a ball mill using 'hot' charcoal in the ratio of 75-15-10. It is fairly easy to make BP that is more powerful than commercial BP with this technique.

 

Powder is then usually granulated by ricing a wet ball of BP through a screen. As mentioned it can also be corned by pressing to a certain density and then breaking apart though most hobbyists don't do this. This is how commercial powder comes because it is a known density so a certain volume gives roughly the same weight each time.

 

These granules are then put through screens to size the powder into the different cuts you listed above. Generally smaller grains burn faster and larger slower assuming it all comes from the same batch. It does make a difference but milling time and charcoal type has a much greater effect on power.

 

Other ratios of nitrate, charcoal, and sulfur also change the power. For rockets regular BP can be too powerful and needs to be toned down. This can be done by increasing the percentage of charcoal and decreasing the nitrate. This has the added benefit of the extra charcoal creating a nice tail of sparks as the extra fuel burns behind the rocket with atmospheric oxygen.

 

Let us know if you have more questions or need something explained further.

[braddsn]

You are starting in the right place, if you have decided to take on pyro as a hobby. I say this because, good bp (consistent, powerful) is the foundation for most of what you do in pyro. You will granulate for lift and burst, you will use bp to coat rice hulls to use as burst, you will use bp when priming stars, and you will use bp when making blackmatch. Each of these things is important, and with good bp, you will have a quality product in the end. With sub-par bp, everything will suffer. If I were to give you 1 piece of advice,I would say invest in a good ball mill. I spent 160.00 on mine (I have 2 now) and out of everything I have invested in, this was by far the best investment.

[BurritoBandito]

To add to what FlaMtnBkr said about good BP being made from "hot" charcoal, this is not referring to the temperature of the charcoal, but the type of wood used to make it. Some common woods used to make "hot" BP include willow, paulowina, and Eastern red cedar (pet bedding).

[B2Crawler]

Thanks for all the great info guys, starting to get a good grasp on it all now. But keep any

the good info coming!

[mikeee]

If you spend a little time researching information on the internet, there are plenty of pdf. files

relating to BP processing, types and uses. There are also a few good video tutorials showing basic methods of making BP and processing into different comps. Depending on what your uses are will determine the methods you use for making your BP. A ball mill is a good tool to have for processing the chemicals you will need for making consistent BP.

[B2Crawler]

I would like to thank all of you that helped out with input, it helped me a lot.

With some of what I learned here, I hand made my first batch of BP, it turned out great.

 

Here is a video of the fire ball pot I made with it...

6" steel tube, 5" of water, 2 gallons of gas, 8oz of BP

 

https://www.youtube.com/watch?v=kCeC209uchU&index=4&list=PL7NZ1tDbkLlid-HhFaz0IleoRGmzldyod

 

As you can see it worked out great for my first time, I do have one more question though. If you watch the entire video and get to the slow mo part, you can see I didn't have any fall out at all, what you actually see burning and hitting the ground is the tin foil I had covering the top of the tube, it was smoldered out by the time I walked up to it so no big deal, but I wish it wasn't there at all.

I am planning on using the foil for covering the tubes during my fireworks show so that stray fall out from other fireworks don't set the gas off prematurely,

So is there any suggestions to keep the foil from catching fire? something I can coat it or spray it with before hand? maybe cover the tubes with something else? any ideas?

[FlaMtnBkr]

Hopefully someone with close prox experience chimes in. But I would try a different material. Something like saran wrap with a rubber band to hold in place. The thin plastic will shrink and ball up into almost nothing from the heat. Also, the stuff from a restaurant supply is supposed to be better than the stuff in the grocery store and is still made of saran that has better properties for this use and what pros use. But I'm sure what you have in the drawer will work fine for the occasional fire ball.

 

If that didn't work I would try something like freezer paper. Or maybe heavy duty aluminum foil. I'm surprised it caught fire but it's because it's thin enough that it gets hot enough to burn with atmospheric oxygen. If it is thicker the surrounding metal can pull the heat out enough that it won't stay burning.

 

So how's that for not a real answer? As I said hopefully someone that has professional experience can give a definitive answer.

[B2Crawler]

Yeah I said tin foil but I actually meant the heavy duty aluminum foil, it doesn't really catch fire itself, its more that the gas fumes and some splash up is on it and that's what burns off. I just want to make sure that later in the year when the grass is dry it doesn't cause a fire from that.

I'm afraid the saran wrap wouldn't protect it enough from the other firework fall out.

[BurritoBandito]

My suggestion is to use a less flammable fuel. Have you ever tried making Cremora fireballs? If you're not familiar with them, try googling up a few videos.

[Mumbles]

Gasoline and liquids are much more efficient on a mass and costs basis generally. Cremora has enough flaming fallout issues of it's own as well.

 

The issues with real saran vs. grocery store "saran" (polyethylene really) are not really applicable here. They're most noted for airburst effects.

[BurritoBandito]

Understood, but the creamer poses very little risk of ignition from fallout of other devices, thus negating the need to shield it. I know that cremoras have a tendency to have fallout too, but it is, in my opinion, better than a premature ignition. Especially because the fallout from a cremora can't saturate surfaces like a liquid fuel. B2Crawler, Mumbles is much more experienced than I am, but I wanted to give my perspective from a safety point of view.

[B2Crawler]

. B2Crawler, Mumbles is much more experienced than I am, but I wanted to give my perspective from a safety point of view.

 

Ok thanks guys, I will do some experimenting with the cremora set up too, For this year though I think I will stick with the gas set up I already have. Like I say the small flaming foil is no biggie, I'm just sort of a perfectionist and try to get everything perfect, (drives my wife nuts). I will keep doing some experimenting with different ways to cover ( protect) the tubes and if I figure something out I will let you know. I just thought maybe someone here may have done the same thing and came up with their own solution.

 

Thanks again for all the suggestions