Best Lift BP For Small Shells (1-2 in.)?

[thepyrotextbook]

I have used many methods of making "BP" for lifting small shells into the air, but even with my best results, I can't quite seem to make a lift powder good enough to shoot my shells anywhere above 60 feet in the air, which is (very) unsafe, and also looks very unprofessional / not presentable. One reason I know that might be holding me back is my charcoal is the bad commercial AF type, and not a better "hot" charcoal. The problem with getting the "hot" charcoal is that I can't currently make it myself, and if I wanted to buy it, I would have to pay a premium price for it ($8-$13 / lb.) and have shipping tagged onto it, as I don't need any other chemicals. I do have a ball mill, but my methods are proving to be bad. Does anyone have any suggestions?

[OldMarine]

Why can't you cook charcoal in a TLUD? It's an almost odorless and smokeless process.

[Boophoenix]

While I'm not the most qualified answer your question I have to ask. How are you processing your BP? Most importantly drying it? Your description sounds like the drying cycle may be to slow or your milling process isn't quite getting it done. You might try granulating with alcohol to see if that changes your results some. I realize commercial AF isn't ideal for BP, but I'd think you could get better performance than that if everything was ideal.

[NeighborJ]

Fireworks cookbook carries hot AF charcoal for sale. It's meant for people who can't make their own and I've heard it's quite fast.

[thepyrotextbook]

I first make sure all the ingredients pass through a 40-mesh screen, and screen mix the Potassium Nitrate (75%) , Charcoal (25%), and Sulfur (10%) together 3-4 times. I then put the ingredients in the ball mill for anywhere from 4-6 hours, and then screen mix in Dextrin (3%). From there, I wet the meal powder with straight water (about 15% of the total weight of the meal powder) and then screen through a 10-mesh screen. I let the granulated meal powder then dry in an about-room-temperature place for anywhere from 1-2 weeks, making sure all the moisture is gone. Lastly, when using the completed powder, I use 10% of the total weight of my shells in BP to lift them. I would have specified this in my initial post, but it was already lengthy to begin with. Sorry 'bout that.

[lloyd]

'Don't know where you live, but if you have it, the sun can be a great helper in getting the powder dry more quickly. In thin layers on papered trays, it'll dry in three or four hours on a warm, sunny day. But you might consider using less water.

 

Always use the minimum water necessary to process anything. Also, "ball milled" can mean a lot of things to a lot of folks.

 

If your mill is optimized for speed and fill, that method should be just fine. But if you don't optimize it, it could likely never reach a complete fineness of grind.

 

Lloyd

Edited February 12, 2017 by lloyd

[thepyrotextbook]

 

Why can't you cook charcoal in a TLUD? It's an almost odorless and smokeless process.

I would love to, but I don't have access to specific types of wood to cook (like willow, paulownia, balsa, etc.) unless you include the normal Spruce/Pine/Fir lumber you would find at any hardware store.

 

 

Fireworks cookbook carries hot AF charcoal for sale. It's meant for people who can't make their own and I've heard it's quite fast.

As I had mentioned before, the premium price for "specialty" charcoals, plus the shipping on them, proves to be a nuisance to me. I am an extremely small scale hobbyist, so ordering only 3 or 4 pounds of their AF Paulownia charcoal and nothing else seems to waste my money on shipping, although eventually I will have to buy that charcoal if I ever pursue anything larger-scale.

 

Are there any recommended screen sizes I should granulate through, or any other lift percentages I can go by to make my BP more usable in the meantime?

[thepyrotextbook]

Lloyd, I know you can help me out with these questions, which are extensions of your comment.

1. What speed / fill is truly optimum for my BP ingredients? (I currently do half fill of media, 100g of BP, 24(i think) RPM, in a 3lb. max load rock tumbler.

2. About how much water do you suggest I use other than my usual 15%?

 

Thank you all so much for helping out! I love this community!

[lloyd]

Textbook,

In order to tell you the optimum speed, I need to know the i.d. of the jar. It would also be helpful to know the gross capacity of it in gallons or pints or cubic inches (that, in order to determine the loads fairly precisely). BUT... the OPTIMUM load, regardless of capacity is:

 

50% of the gross volume in media, and 25% of the gross volume in material to be ground. 3lb 'max load' sounds like a TINY jar!

 

The diameter of the jar AND the diameter of the media determine the speed. So, also, what size media, and what material?

 

---

 

For water... I'd suggest starting down around 10%, then IF NECESSARY, slowly creep up. But keep always in mind that dextrin takes a few minutes to activate -- so what looks like too little water initially may still end up being enough after the dex' has gotten sticky.

 

Lloyd

[lloyd]

The formula for calculating the optimum speed is:

 

 

OptimumSpeed=0.65 * ( 265.45 / sqrt(jar_ID" - media_OD"))

 

Say the jar were 6" i.d., and the media were 3/4" o.d.

 

Then 6"-.75" = 5.25" The square root of that is 2.291

 

265.45/2.291= 115.85

 

65% of that is 75rpm

 

Recalculating for a 4" jar with 1/2" media:

 

4"-0.5" = 3.5" sqrt(3.5)=1.871

 

265.45/1.871=141.89

 

65% of 141.89=92.22rpm

 

LS

Edited February 12, 2017 by lloyd

[thepyrotextbook]

I'll need to get the specifics on my mill/jar, but the milling media is ceramic. I'll get back to you soon.

[lloyd]

Your jar sounds quite small. Ceramic media may not be dense-enough to do the job in small jars.

 

Lloyd

[thepyrotextbook]

Okay, here are the jar specs:

 

ID: 4 inches

Height: 4 inches

Inner Volume: About 50.25 cubic inches (if i did my math right)

 

I also did the equation for optimum speed, but it came out as 243 RPM, which is insane, so I might need to increase my media size.

And in terms of other media, what is there. I know lead is common, but are there any other media types that could work too?

 

NOTE: For some crazy reason, I thought my mill ran at 24 RPM, but it actually runs at 60 RPM with a "full" load. I need to get my facts straight...

Edited February 12, 2017 by thepyrotextbook

[lloyd]

Yeah, that's an insane speed. You must've done the calculations incorrectly. For a 4" jar with 1/2" media, the speed should be about 92 rpm.

 

 

In a 4" jar, any media larger than about 1/2"o.d. will be very inefficient. I can tell you for a certainty that ceramic media in a jar that small is not capable of grinding powder to its ultimate fineness. You need more-dense media, not larger than 1/2" o.d.

 

I know there are prejudices against lead, but hardened lead media wears very slowly. The only other suitable medium would be 1/2" stainless steel.

 

For the SS media, there is some fear in the industry about sparking, although it's not likely to happen in a jar that small. But you have the option of barricading your mill.

 

That jar would require 25 cubic inches of media. That's by gross volume, not by the aggregate volumes of the individual spheres. Spheres in a mass are approximately 60% solid and 40% air.

 

To that, you would be able to add 12.5 cubic inches of powder (perhaps a little more, but not much!). That's a really TINY amount of powder -- about 3oz! Un-ground, screened raw ingredients run about 0.4g-0.6g/cc. Pressed-and-corned powder weighs very nearly 1g/cc.

 

Running the math: 1cu.in.=16.39cc. 12.5*16.39cc= 204.875cc . 204.875cc * 0.4g/cc 81.95g. 81.95g/28.35g/oz = 2.89oz.

 

Lloyd

Edited February 12, 2017 by lloyd

[thepyrotextbook]

Lloyd, thank you so much for all your help. I'll try to make a new batch of BP soon, using 0.5 inch lead media, and only using 10% water for granulation. I will post as soon as possible on the results, but it might be a while as it is quite rainy / overcast right now where I live. One last question: where would you obtain lead media? (Sorry if this is a bother)

[lloyd]

No bother, 'book'. The only way to perpetuate this hobby is to pass on information to others. I'm 'semi-retired', so this is part of my list of 'duties'. <grin>

 

I beg you to take another look at my last post. I re-figured the powder load to about 2.89 oz... I had miscalculated it in the first iteration of that post.

 

Lloyd

Edited February 12, 2017 by lloyd

[lloyd]

Oh... sorry... lead media....

 

I'm not sure he's 'current' right now, but Caleb Kessinger carries it. He works his butt off casting it, but is always bought-out.

 

His web site is: www.woodysrocks.com

 

Lloyd

[lloyd]

PS... modified the speed post to also show the calculations for a 4" jar with 1/2" media.

 

LS

[OldMarine]

I've got media from Caleb and it's almost too pretty to muss up with chems!

[thepyrotextbook]

I'll be ordering my lead media within the next 24 hours, so hopefully I can let you know the results very soon. Thank you all, Lloyd, OldMarine, NeighborJ, and Boophoenix, for helping me with my BP questions. You might see me again in other posts too...

[lloyd]

I certainly HOPE we'll see the results of your successes!

 

Lloyd

[Mumbles]

1lb of fancy purpose bought charcoal makes 6.67lbs of BP. I don't know about you, but I can never have enough chemicals. Grab some the next time you're ordering something. Several suppliers carry hot charcoal. A pound of charcoal might seem to be an excessive price, but it will last a long time making 1 and 2" shells. You could also just use more. 10% is not an absolute, just a guideline sometimes quoted.

 

http://www.ihaveadotcom.com/cart/index.php?main_page=product_info&cPath=72_119&products_id=284

http://www.pyrochemsource.com/Charcoal-ERC-ERCCHARCOAL.htm

https://fireworkscookbook.com/shop/charcoal-paulownia-ground/

https://fireworkscookbook.com/shop/charcoal-eastern-red-cedar/

 

In all honesty, a majority of woods you can find in nature will out perform hardwood airfloat. Willow is often found near streams, ponds, and bodies of water. Maple can work fine, and is supposedly what Goex uses or used. Eastern Red Cedar is commonly sold as pet bedding shavings and has been popular recently. SPF wood has also been used with success assuming it's lightweight, not sappy, and relatively free of knots. Different portions of the US use different exact wood varieties. Cooking it is easy. If you lack a space to cook charcoal, you probably also lack a space to safely ball mill something or make pyrotechnics. It can even be cooked on a grill as a last ditch scenario.

 

I agree with most of the comments about ball mills and ball milling already mentioned. It should be noted that the 2, 4, 6hr type times quoted are for optimized mills. If you're running an underoptimized mill, which is sounds like you are, some of the deficits can be made up for with longer run times. When I first started I had an unmodified Harbor Freight rock tumbler that spun around 45-50 RPM IIRC, and was not quite fully loaded with lead. Using willow charcoal it would take somewhere between 8-12hr to produce good meal powder.

 

One last thing. A lot of things in pyro are by feel and experimentation to some degree. People will toss out values for mill times, mill capacities, wetting levels, drying times, etc. Treat these as guidelines or starting points, but use what works for you. BP not done in 6hr? Try another couple and see if things improve. 15% water giving crumbly granules? Try more. 15% water giving a sticky mess? Try less.

[lloyd]

Mumb,

I agree. But you said you use lead, and he said he was using ceramic media in an undersized, not-optimized (and probably over-charged with material) mill. In a jar that size, ceramic is not dense enough to have enough impact to result in full milling to 'final fineness of grind'. Ceramic just doesn't have the impact to do that in that small of a jar.

 

But I do agree with your "do what works" philosophy. That's what I've always done. Except for my ball milling investigation (which is well-proven in industry, not just fireworks), the rest has always been, "Try it, and see if it works. If not, try something else!"

 

Lloyd

[thepyrotextbook]

Wow... even Mumbles got in on this thread! Anyways, I do have VERY sufficient space to make charcoal, so you don't have to worry about my safety all to much, and your advice on trying what works best is something I have tried for a while. I have made numerous batches of BP, and each one has gotten better than the next, but the results were still lacking. I thought now might be a good time to ask the community, so people like you and Lloyd (the greats) could really help me out. I guess I'm a little impatient with my BP progress, and a little lazy for not cooking up a small batch of charcoal. It just felt like I was devoting all my pyro-time to black powder, as I already have made leaps and bounds on my color/effect compositions (the green one is my profile pic). But that's just how fireworking is sometimes, and it certainly is the part that makes hobbyists stick to what they're doing. Try, try, try again, you could say!

[zzzybil]

I first make sure all the ingredients pass through a 40-mesh screen, and screen mix the Potassium Nitrate (75%) , Charcoal (25%), and Sulfur (10%) together 3-4 times. I then put the ingredients in the ball mill for anywhere from 4-6 hours, and then screen mix in Dextrin (3%). From there, I wet the meal powder with straight water (about 15% of the total weight of the meal powder) and then screen through a 10-mesh screen. I let the granulated meal powder then dry in an about-room-temperature place for anywhere from 1-2 weeks, making sure all the moisture is gone. Lastly, when using the completed powder, I use 10% of the total weight of my shells in BP to lift them. I would have specified this in my initial post, but it was already lengthy to begin with. Sorry 'bout that.

why do I think too much charcoal is the issue ? I expected your formula to be the issue . As in 15% charcoal ! Do others use this much charcoal with good results ?