can't seem to make decent BP

[tentacles]

The best solution is to press bp into pucks. That way you can use less dextrin and less water and get a product even harder and more solidified that granulating produces.

 

If you're pressing into pucks there is no reason to put dextrin in the mix - straight dampened (2% or less even) BP will press rock hard. And I disagree with it being the best way - if you go through much BP, pressing and corning becomes a huge PITA.

[Mumbles]

You can do what you want. I use 5% regardless all the time. My powder is still plenty hot. I definitely prefer the extra hardness you get from the extra dex in my polverone. That stuff isn't supposed to burn fast anyway, so no issues.

 

You guys are too concerned with speed of your powder. It all seems like tricks to power up substandard starting material to me.

 

With Dagabu claiming 70% isopropyl will activate dextrin, maybe there is some truth in the alcohol creating hard granules. I've heard of people having star hardness issues in the past with more than 25% alcohol.

[dagabu]

With Dagabu claiming 70% isopropyl will activate dextrin, maybe there is some truth in the alcohol creating hard granules. I've heard of people having star hardness issues in the past with more than 25% alcohol.

 

Very true, but that wasn't the question at hand. The Isopropyl will NOT activate the dex, only water does that. Straight water does a much better job of activation but drying can take four times as long. I personally dump a 16oz bottle of 70/30 in a 32 oz spray bottle with 16 oz of distilled water. It speeds the drying but still activates all of the dex.

 

I use Cowboy lump charcoal for just about everything, same speed as Service and Skylighter and at $5.00 a 20# bag, you cant go wrong. I find that 2% dex does an ok job on grain hardness but so does SGRS and others. I have other charcoals as well and they are great but only for experimentation since they are too hot for my rockets.

 

My mix with denatured alcohol is still drying and I wont have the weight down to starting for another day.

 

Dave

[Bonny]

I press and corn my BP for lifting. I use about 5% water by weight (with a splash of alcohol) and no dextrin. I have corned dry and wet with no real difference in performance as far as lifting shells. As noted above by Tentacles it is a PITA when doing larger amounts...which is why I built a passfire style corning drum setup for my ball mill to lessen the workload. The corning drum is fairly loud though...need to really crank up the tunes in my garage to try and cover the perfectly timed cadence of the media tumbling off the lift bar. My powder I'm sure is not the fastest but as Mumbles said, speed is not everything, my powder works for me and that IMO is most important.

[Swede]

Pressing and corning is fun for me because it truly creates a BP that is like commercial... in terms of handling. Riced BP can easily be faster than Goex or Elephant, but you will never get the density, the hard little grains, like commercial unless you press.

 

Most guys think I'm nuts to use binder for pressed BP, but I like 2% red gum, alcohol, press, and break the pucks when they are about 75% dry. I think the alcohol speeds drying tremendously, it certainly does not dissolve any nitrate, and the grains, after tumbling with graphite, cannot be distinguished from commercial. They will store, pour, and handle without any breakdown or dust. It's more of a curiosity or chalenge than anything practical or necessary.

 

Here are two 5 gram sample bottles, one with riced BP, the other, pressed and corned. It dramatically shows the density improvement by pressing. The grains tink

like little ceramic nuggets, and already the riced BP is breaking down into dust. One thing pressing does do for you is allow volumetric measurement after a bit of experimentation.

 

http://www.5bears.com/firew/press100.jpg

[dagabu]

Pressing and corning is fun for me because it truly creates a BP that is like commercial... in terms of handling. Riced BP can easily be faster than Goex or Elephant, but you will never get the density, the hard little grains, like commercial unless you press.

 

Swede, can you show us what you use for pressing pucks? I'm get my lathe this week and would like to get an idea of what I should build.

Dave

[Bonny]

Swede, can you show us what you use for pressing pucks? I'm get my lathe this week and would like to get an idea of what I should build.

Dave

 

 

I'm not sure what Swede uses, but any plastic pipe re-enforced with hose clamps will work. You can try the passfire type with the split pipe, but that didn't work for me...broke all the clamps and split wide open. I use 3" PVC with UHMW or Nylon pistons and a 12ton jack. I press about 5 or 6 ~3/8" pucks at a time. i've never tried with the red gum and alcohol, only water with no binder... and my pucks have the ceramic 'clink' when still damp.

[Twotails]

As i said i use acetone, but the ratio i use leaves hard peices of BP.

 

50/25/25 water/91% isp alcohol/ Acetone.

 

I use that ratio over the one i was using before, simply to try it. I like the addition of acetone, for it evaps fast.

 

I dont use just acetone, inless im making lances.

[Swede]

The diameter of your rig and the capacity of your press determine the density you can get. If you have a little car jack rig, then the diameter of the setup needs to be a bit smaller to get acceptable PSI on the dampened BP. I use an aluminum tube + ram that was designed as a comet pump, and is only about 1.5" diameter. I work on a pretty small scale. If you have a 20 ton hydraulic press, then 3" or more is possible, but as Bonny mentioned, the tubing + ram need to be pretty stout. I have not noticed an ability to overpress... once it reaches 1.6 to 1.7 or so g/cc, it seems to be very hard to get it any denser. So wail away on it with whatever you have, and hope the rig doesn't burst.

 

If there's too much liquid, a shocking amount of fluid will be pumped out. From the few experiments I've done, with the correct amount of liquid in the BP, there might be a few drops or a tiny bit of weeping from the bottom of the ram, but more than that means there is too much liquid. The moistened BP is nowhere close to a dough when it goes in; it still looks and feels like a powder, maybe a slightly clumpy powder, but definitely much less moisture than most would guess.

 

Again, it's one of those things you do for fun, or the challenge of truly replicating commercial BP - and definitely not necessary for 99% of pyrotechnics. Plain ricing does very well all by itself.

[Mumbles]

I was able to achieve 2.0 g/cc on a test once. It preformed worse than 1.7. I had screen granulated, 1.4, 1.7, and 2.0. 1.7 was best. The grain size was not very controlled so I think that definitely affected results.

[stormyweathers]

i finally got some decent results

i over wetted the powder with acetone and didnt have time for it to dry, so i just left it out

after it hardened into a cake, i just broke off a piece and tested 5g of that

i also lightly ground it with a mortar and pestle and tested 5g of that mix

 

holy crap, i get that nice WOOOSHH and before i know it its all gone

its probably not perfect, but it works and i can fire a decent projectile in my cannon with it

[Ralph]

no dextrin is water soluble and not soluble in isopropyl you need the water the alcohol reduces the surface tension of the water *making the water wetter) and decreases drying time slightly

[dagabu]

OK, kids. Im going to make a new batch of BP and want to have you all from APC to tell me how you want it done. I have all the chems, mills, screens etc so give it your best shot!

 

This will be based on tabulating all of the suggestions and using the one that is most recommended.

 

-Charcoal, Willow or Cowboy Lump

-Sulphur, well, its sulphur...

-KNO3, Multi-K, no cab-o-sil

 

The goal is to replenish my 2FA supply.

 

D

Edited October 6, 2009 by dagabu

[Swede]

Dagabu, you're not a new guy!

 

Are you going to press the powder? Most guys would say to add a binder if you are going to simply turn the freshly-made BP into a dough and rice it through a screen. I like red gum and alcohol, others like dex + water.

 

If you are going to press, then corn, most guys say "no binder" but I still use it. 2% red gum to all BP batches. If I know it's in there, I have the choice to rice, press + corn, or dampen and press (per Sleeter, with an organic solvent) for end-burner rockets... standard 75:15:10 is too hot for core burners and I ended up with 4 out of 5 CATO.

 

Cowboy lump makes decent BP for most tasks. Hand sorting by density (Mumbles) is a great idea - save the heavy lumps for BBQ, use the lighter lumps. For tasks requiring speed, then go willow.

 

If my ingredients are lumpy or prills, I load the jar lighter, use a bigger jar, and flog the lumps and prills into submission. I've never seen the need to reduce prills to powder, or charcoal to dust, before loading. The charcoal pieces I do break down into fingertip-sized nuggets.

 

Hmm, what else? If you don't know your mill, then pull a gram every 2 hours, put the samples in a little ziploc, and label them. You can burn the samples sequentially and find the point where there is no improvement, and that becomes your mill time!

Edited October 6, 2009 by Swede

[Aquarius]

Swede, you use Cowboy for endburnes also? My coreburners works like a charm, but it seem like the endburners are more difficult to dial in. Or I might be working on a too small scale.

[dagabu]

Dagabu, you're not a new guy!

 

Are you going to press the powder? Most guys would say to add a binder if you are going to simply turn the freshly-made BP into a dough and rice it through a screen. I like red gum and alcohol, others like dex + water.

 

If you are going to press, then corn, most guys say "no binder" but I still use it. 2% red gum to all BP batches. If I know it's in there, I have the choice to rice, press + corn, or dampen and press (per Sleeter, with an organic solvent) for end-burner rockets... standard 75:15:10 is too hot for core burners and I ended up with 4 out of 5 CATO.

 

Cowboy lump makes decent BP for most tasks. Hand sorting by density (Mumbles) is a great idea - save the heavy lumps for BBQ, use the lighter lumps. For tasks requiring speed, then go willow.

 

If my ingredients are lumpy or prills, I load the jar lighter, use a bigger jar, and flog the lumps and prills into submission. I've never seen the need to reduce prills to powder, or charcoal to dust, before loading. The charcoal pieces I do break down into fingertip-sized nuggets.

 

Hmm, what else? If you don't know your mill, then pull a gram every 2 hours, put the samples in a little ziploc, and label them. You can burn the samples sequentially and find the point where there is no improvement, and that becomes your mill time!

 

NO, you don't understand, I have been making BP for along time but what to experiment with mass choice... You decide what it is going to be. Best comp wins!!

 

I will then make burst, lift, motors out of it and show the results. It sounds like fun

[TheSidewinder]

You want to replace your 2Fa supply, eh?

 

OK... I'll bite! Here's a recipe....

 

KN03: As long as it's pure, it's (almost) irrelevant what particle size you START with. But let's say table-salt particle size. 76%

 

Charcoal: airfloat Willow, 14%.

 

Sulfur: Like you said, sulfur is sulfur. But to be nit-picky, rubbermaker's sulfur (or one that is as acid-free as you can get), 10%

 

Binder: Red Gum, additional 2%.

 

Milling: 24 hours. (Yes, 24 hours. That's not a typo.)

 

Dampen this mix VERY slightly with 75% alcohol-25% water. No more than 2-3% total wetting agent. Press immediately after wetting.

 

Pressing: Press to a dry-weight of 1.7 gm/cc. Puck size: 3 inch diameter, 2 inches thick.

 

Corning: Corn it, then sieve out the correct size for 2Fa. I don't remember what mesh that is, sorry.

 

 

How's that?

[dagabu]

You want to replace your 2Fa supply, eh?

 

OK... I'll bite! Here's a recipe....

 

KN03: As long as it's pure, it's (almost) irrelevant what particle size you START with. But let's say table-salt particle size. 76%

 

Charcoal: airfloat Willow, 14%.

 

Sulfur: Like you said, sulfur is sulfur. But to be nit-picky, rubbermaker's sulfur (or one that is as acid-free as you can get), 10%

 

Binder: Red Gum, additional 2%.

 

Milling: 24 hours. (Yes, 24 hours. That's not a typo.)

 

Dampen this mix VERY slightly with 75% alcohol-25% water. No more than 2-3% total wetting agent. Press immediately after wetting.

 

Pressing: Press to a dry-weight of 1.7 gm/cc. Puck size: 3 inch diameter, 2 inches thick.

 

Corning: Corn it, then sieve out the correct size for 2Fa. I don't remember what mesh that is, sorry.

 

 

How's that?

 

Corn damp or wait till dry?

2" thick 1.7 gm/cc? That's a little tricky. 1", for sure, 2" the center will still be soft.

[TheSidewinder]

Corn when dry.

 

Make that 1" thick then. We're shooting for consistency here, so a soft center is no good.

[Swede]

Swede, you use Cowboy for endburnes also? My coreburners works like a charm, but it seem like the endburners are more difficult to dial in. Or I might be working on a too small scale.

 

No, honestly, I use willow from the charcoal guy. I think that is one of the problems with cowboy. It makes usable BP but it can vary from batch to batch, and maybe my rocket technique sucks, but the only way I could find to be consistent was to use a specific charcoal, then vary the proportions. A while back, I bought a lot of the willow charcoal, and am still going through that one batch.

 

I recently bought 5 pounds of balsa charcoal from a passfire guy to play with, and I'm looking forward to experimenting with it, but I expect to have to alter proportions again. Rocketry to me is still a bit of voodoo... sometimes, you don't know what you'll get, and I hate making a nice header only to have a nasty CATO on liftoff.

[dagabu]

I use willow from the charcoal guy.

 

Who is the charcoal guy? Custom Charcoal?

[Aquarius]

Thanks Swede, I don't have willow right now, but I have some quite hot pine BP.

Guess I'll start making a new set of tooling today, I'll try the 5/8 rods I have lying around first.

[Bonny]

Corn damp or wait till dry?

2" thick 1.7 gm/cc? That's a little tricky. 1", for sure, 2" the center will still be soft.

 

A 2" thick puck will not have a soft centre if you leave under pressure for a longer period of time. I used to press thick pucks1-2" , but found them harder to break up when dry. When I press my 3" diameter pucks (no binder) I use about 5% water with a splash of alcohol and a 12ton jack. Anyway, press as hard as you can (or measure your calculated thickness for density). Let it sit under pressure for 10-15 min. Repress and wait 10-15 again. Do this one more time and you should have good and solid BP all the way through even thicker pucks.

[Swede]

Who is the charcoal guy? Custom Charcoal?

 

Yes, this guy.

 

I bought a boatload of willow months ago before I learned that the alder makes BP maybe 98% as good as willow at a much cheaper price. I'll go alder next time. I was going to buy some a while back but I hesitated because I had so much willow to go through.

 

Making charcoal is cool but it's one of those things where, to me, it's worth buying for the time and work savings.

[jm82792]

I apologize for posting here(for some reason I can't start a thread),

I just joined up and have a question related to BP.

 

I am new to firework making in general(although I know chemistery decently, the jist of making them,

have done tons of science related projects before I graduated and know safety and such.....),

lots of reading over the years but I haven't done much but want to this new year.

 

Basically can I make crappy green powder per skylighter's directions and make some decent

flying fish fuse and other fuse based mines work and can I launch a few 1 inch shells decently ?

Can I use ebay for the charcoal powder, sulfur and potassium nitrate if I make sure it's high grade, pure and fine?

Could I use a 40 mesh mesh from ebay realizing it won't last that long since it would be cheap to sift the chemicals?

 

I'm out on an Island and shipping from skylighter is more than what I'd be ordering,

typically people form ebay ship USPS that is much more economical and reasonable.

 

 

Sorry not trying to hijack

Edited October 15, 2009 by jm82792