Corning BP Optimization thread.

[TYRONEEZEKIEL]

Hello, I have recently started to increase my batch sizes of comps when doing pyro, and it has got me thinking economically. Things like how much money do I have in each shell, each star batch.... etc. Now that I have been getting more comfortable with my processes, my brain has drifted towards thinking of optimization. Now I have corned my BP for about 6 months now, and I am very comfortable with my results. I would like to share my information here and get some input. Maybe we can really get the process down to a perfect science together.

 

So my goal this session was to corn my BP into lift specifically, so optimally, have 2 goals.

1. I want 100% 2FA.

2. I want 0% corning dust.

 

Now of course both of these wishes are impossible, and obviously if my first criteria were true, then the latter would also complete itself. I listed both of these criteria as possible goals to shoot toward. Knowing that neither will ever be completely realized, I have set 2 parameters of which to optimize my corning process. Simply put, I'd like as close to 100% 2FA with as close to 0% corning dust as possible.

 

Here is my current process.

 

1. Mix 227g BP (half pound) with 7.7g water/alcohol (75/25) thoroughly and press to 1.7g/cc until I had 5 pucks

2. After drying, I broke the pucks with a wooden rod in an old helium container which I orginally intended to be a star roller.

3. I emptied the bucket out onto my sizing screens.

4. Now I take a handful of BP chunks and crush them about 20 whacks or so, then screen. I do this to avoid overpulverizing any one area too much.

5. I repeat the process until all BP falls through screens.

 

Here are my results.

 

1135g BP starting

 

717g 2FA 63.17%

197g 3FA 17.36%

195g Corning dust 17.18%

26g lost(airfloat, lost flyaway pieces etc) 2.29%

1109g Total 100%

 

 

Now I am rather impressed with how little loss of BP there is. I feel like I can live with 2.3% total loss of BP this early on. Although at this rate a 10 lb batch would have a net loss of 104g which is pretty substantial. I do have a feeling that loss would not increase linearly and would ultimately be more efficient with bigger batches, but we will stick with 2.5lb for now.

 

So, I leave this initial experiment to you fellow pyros. What are your thoughts?

[Bobosan]

Since you are experimenting, might try 1% dextrin to reduce the airfloat loss and dust amount.

[TYRONEEZEKIEL]

I certainly don't need the dextrin. My grains are hard as rocks, and I want to stick to pure BP with no binder.

[Bobosan]

Just re-use anything less than 2FA in the next batch

[TYRONEEZEKIEL]

I have been re using the mill dust for that, or Ill coat hulls with it, but It is just so much work to reprocess all that BP.

[Bobosan]

Just save and label the non 2FA BP for other pyro related items that can use primes or dusting as you mention. If you get too much of one category, throw it back in with the next full run of BP manufacture. I agree with saving some time on the process but it is what it is.

[Nessalco]

IMO, the key is to corn as soon as the pucks come out of the press, while they are still damp.

 

I press eight 50 gram pucks at a time in a 2.5" comet pump, with carbon fiber dividers between the pucks. There is about a 20 minute total dwell time to fully press a stack that high.

 

After pressing, I eject the pucks from the pump, then reload it and set it in the press. While that batch is pressing I'll corn the first while still damp.

 

I put 2 pucks in a bag I made up from kevlar, then use a wooden mallet to break them up on a 1.5" aluminum plate. I'll hammer away until the larger pieces are fully broken up, then screen. I then use a 2.5" diameter aluminum rod vertically in a heavy plastic tub, with a rocking motion, to break up the smaller pieces until they all go through a 4-mesh screen.

 

Pump up the stack.

 

Corn 2 more pucks and screen. Repeat until all pucks are corned, and the next stack is fully compressed.

 

Repeat as necessary. Any fines you don't want simply go back in the batch to be pressed. I've done 3 kilos of BP in 2FA, with only 80 grams of fines that weren't worth the trouble of putting back in the pump. Total time about 3 hours, not counting mill time.

 

Kevin

[Mumbles]

My one main comment is how are you getting both 2FA and 3FA? Their ranges of grain size overlap. The amount of corning dust does seem high too, but I suspect that you consider anything smaller than 3FA to be dust, so that would make sense.

 

Ignore a majority of the pdf, but I'd be interested in trying steps 15-18 on pressed pucks to get an optimal amount of 2FA sized pieces. (note: his "FA" sizes are also vastly off)

http://wpag.us/learn/How%20To%20Make%20Black%20Powder.pdf

 

On your next batch, I'd suggest doing some wet and some dry and see if that results in any change for you. I can see benefits to doing both depending on what you need. The immediate re-processing of the material you don't want seems to be most beneficial for your goals.

[TYRONEEZEKIEL]

Mumbles. I give it a hard cut off between grades by my screens. I suppose my 2FA I am referring to is the first 2 of my stacked screens, and the bottom screens are my 3FA. With corning dust of course being on bottom. So in that respect, that is how I achieve my decided grades.

 

As far as using a putty knife and roller, I'd be very impressed to see that happen. My pucks are about 3/4" thick and very very hard. Im sure I could reduce the thickness and stack the pucks in my die, but that draws out on efficiency.

[Nessalco]

Thinner pucks would help - a lot easier to break up. Mine are 50g pucks, just shy of 3/8" thick.

 

Kevin

[TYRONEEZEKIEL]

I may experiment with thinner pucks. In fact, I wonder if I get my pucks to be the thickness of my desired grains, all I would have to do is bust them up one time each.

[FlaMtnBkr]

The only thing I would suggest, which has been mentioned, is to break up while still damp. That said, I found corning to be a waste of time. Corning actually slows down powder that you worked so hard to mill and make fast. I find 'milled pulverone' to be easy and fast to make and it is hot and when screened can be used just like corned powder. Except I wouldn't measure it by volume and use it in a firearm. That is probably the only thing I would make corned powder for.

 

Also, with milled pulverone there is not much dust and I doubt any lost but I haven't weighed it to verify. BP is like the flour of pyrotechnics, and I want to be able to crank it out. Pressing the snot out of it just to break it up just uses a lot of time and energy and the advantages just aren't numerous enough to justify, for me.

 

Plus, it doesn't work good in rockets which I want to be able to use my BP for.

[TYRONEEZEKIEL]

As far as corning goes, I store my BP for months at a time, so I really like the idea of infinitely durable grains. I also have not experienced my lift being slow by any means with this. My grains arent polished, they are very rough and jagged. I would rather use a different rocket comp than just BP, so that isnt too much of a problem. To be honest, pressing and corning takes about 30 minutes of working time for a 2.5 lb batch of BP (not including drying of course). I dont think that running that much BP through a screen for polverone would be too much quicker.

[FlaMtnBkr]

Everyone has their own way. That is just mine. I couldn't make it that fast when I experimented with it. I'm not sure I could press it in that amount of time with the dwell time I allowed, let alone bust it up. But I probably don't move as fast as I could. And I know I dont have twenty percent 'losses'.

 

And I wasn't saying corned powder isn't fast. It just isn't as fast as it is not corned but that is just nit picking. However, I have BP in the magazine that is probably from '05 and has been shuffled around a lot and is still mostly intact and it has no binders. Unless you plan to be stepping on it, my method produces plenty durable grains with just water added to it. If dextrin was used I can't imagine it ever breaking down. I haven't found I need it and I can use my BP for everything and is what works for me. I would be willing to bet 90% of people who make BP don't corn it. But you know what they say about percentages. 78% are made up on the spot.

[Nessalco]

I use both corned and riced BP, for different purposes. The corned powder is for cylinder shells and spolettes, the riced for break charges in ball shells, maroons, and the like. I don't make rockets, but when I make gerbs I simply rice the powder with alcohol and no binders to keep the dust down.

 

I use corned powder for lift charges as well, because I find it to be more consistent. Besides, it's pretty.....

 

YMMV

 

Kevin