Critique My BP

[TYRONEEZEKIEL]

I pasted this from passfire. I figured 2 forums would offer a better wealth of information, so if you see it over there also, it was me.

 

Hello. I am having a bit of trouble in making my BP as fast as commercial. At the moment I lift shells with 1/10 weight using commercial powder of 3-4fg. The grains are very tiny. Until this week I granulated my meal with +3% Dextrin through a window screen for lift. At that I still needed 1/6-1/7 weight of shell to make equal lift. This is not acceptable to me. I am doing everything by the book here and I still cant get it right. So I will lay out my process and show you exactly how I make my powder. Hopefully some of you veterans can help me out.

 

Here is my ball mill. It is perfectly optimized according to Sponenberg's book.

http://s14.postimg.org/76wp4ozi5/IMG_0234.jpg

It is 4" ID and uses 200 1/2" lead balls. They are non-hardened lead balls used in 50 caliber rifles. My ingredients I use are:

 

75 Haifa-K KNO3 -- I dry it just to make sure before every use.

15 Charcoal --- I use either white pine I make myself, or skylighter's airfloat. Either version wont make the cut in my case

10 Rubbermakers Sulfur -- I obtained this from Rollingthunderpyro.

 

My mill in this set up is optimized at exactly 1 pound(454g) of BP. When I take my BP out of the mill it is very gray, not yet black, and it is clumped around the front and back where the powder just wont get any finer.

 

Here is a picture of some meal for color reference. Keep in mind. this is half jar meal and half corning dust, so dont mind the particle size, I promise my meal from the jar is fine enough I can read my fingerprint in it.

 

http://s14.postimg.org/mr42v89ml/IMG_0235.jpg

 

After milling, I dump it into a bucket with a 15 mesh screen and roll it around and the media knocks most of it through the screen, I have to break some of the big clumps between my fingers to help it pass through. From there I mix half a pound of BP (226.8g) with 7.6g of 50/50 water alcohol mix. It takes a bit of time, but I work all the water in. I am using the same percentage of water/alcohol as shown in Dan Williams' page. I then press it to exactly 1.7g/cc using a 12 ton jack with my powder die which is based off of Sponenberg's die he used to make.

 

http://s14.postimg.org/i19jsvt8d/IMG_0236.jpg

 

Here is the finished puck out of the die. It is still gray, and after drying it is still the same color. Never through my process is my powder ever actually black like the grains on the passfire background. And just to verify that my math is right, My powder 226.8g is pressed into 133.4cc. This gives me 1.7001g/cc So I am right on the money there.

 

 

http://s14.postimg.org/vjgg565dp/IMG_0233.jpg

 

 

I then wait until the pucks are dry, then I will initially crush them with the jack in the center to break them into 4 or so pieces. I then put them 1 or 2 at a time in a helium container that I have modified into my star roller. I crush them with a wooden rod that came from an axe handle. I sift them with the same 15 mesh screen and then a 40 mesh screen underneath that. Here are the 2 screens. The little cup there is what we use for communion at my church. I left it there for size reference.

 

http://s14.postimg.org/5cjumychp/IMG_0231.jpg

http://s14.postimg.org/et52fu6yl/IMG_0232.jpg

 

Now I have been testing all 3 grades of my BP the Corning dust, the 40-15 mesh, and the 15- mesh stuff. The 40-15 lifts the best so far but its still not good enough. I test my powder using a baseball and a 3" HDPE mortar which is 2' long.

 

That is my process of making BP. I still can not get it to work optimally even after pressing and corning, which I thought would have really helped me out. I still need to use way more than I am wanting, and I finally have decided to get some help from the pros. So if you see anything that I am doing wrong/not doing right, please tell me fellas. I do appreciate your help

[pyroviper]

You could try a different charcoal. I like to use willow, and have been very pleased with it.

[Mumbles]

White pine should make decent lift in the same ballpark as commercial BP. Out of curiousity, what size of shells are you lifting? Using 10% of a commercial BP would make it seem like a reasonably small or light shell.

 

I would try a known hot charcoal. That will tell you if it's your materials or your methods. The other thing I would try is milling about half the charge that you normally do. Having used a similar sized mill before, I had good results with around 200g of material. Even that was a little over charged for me. Remember that you want the charge to basically just fill in the gaps between the media, and just cover them a little bit. This normally comes out to around 1/4 of the volume of the barrel. Different charcoals vary greatly in their fluffiness, so that could very well could be the difference.

 

You don't mention how long you're milling, but have you ever tried additional milling times to see if there is any improvement? With a well tuned mill, about 4hr is a good starting point.

[TYRONEEZEKIEL]

I am lifting 3" shells. Since optimization I have been milling for 3-4 hours. Prior to that, my jar was only off optimization very slightly because of how I charged my jar. I used to mill 8 hour minimum and up to 24 hours on occasion just to be sure. The speeds are the comparable. I havent had much increase in power except for corning. It did seem to help out a bit. I truly dont think its my mill, but I could be wrong. I didnt mention mill time previously because I just used sponenbergs suggested 3 hour mill time.

[Pyrophury]

I am lifting 3" shells. Since optimization I have been milling for 3-4 hours. Prior to that, my jar was only off optimization very slightly because of how I charged my jar. I used to mill 8 hour minimum and up to 24 hours on occasion just to be sure. The speeds are the comparable. I havent had much increase in power except for corning. It did seem to help out a bit. I truly dont think its my mill, but I could be wrong. I didnt mention mill time previously because I just used sponenbergs suggested 3 hour mill time.

 

I'm not sure why you expect to see an increase in performance by corning, this should actually slow it down if anything. So if your corned BP is as fast as your granulated, then you're corning method is sound.

 

I recently corned a batch of BP in pretty much exactly the same way, only I used 10ml water with 5% alcohol per 100g of mill dust. I've no doubt some of the potassium nitrate leeches out with the water during pressing, but not enough to make a significant difference. My screen granulated BP burns slightly faster, but I actually prefer this method and the hard, dense, durable grains that corning produces.

 

This is the result:

 

 

If you want to increase burn speed, then as already suggested, try milling for longer or using willow charcoal.

[Bobosan]

Try reducing amount of Dextrin a percent or two and be sure to use distilled water.

[pyrogeorge]

When i made some BP pucks for lift i had a poor quality BP granules than my screen method.

I don't know why..I used the same BP as in the screen method.After this i make only with screen,easy and fast making than to press pucks.

[FlaMtnBkr]

For hot charcoal look up Algenco on here and mumpyro on passfire.

[SunDevil]

TYRONEEZEKIEL,

 

I think that the advice that Mumbles gave you about the quantity of powder being milled is a key factor here. I think that the quantity that you are milling is just too much to adequately mill to an extremely fine size. I had this same problem initially several years ago, as I was using a one quart milling jar, charged with 615, 50 caliber pure lead balls. The powder came out looking good but it was not quite at the high performance level that I wanted to have for lift. I backed off the amount of powder to be milled from 450 grams to 300 grams. I also stopped the mill (by remote control) and gently redistributed the contents every two hours. Total milling time for each batch was eight hours.

 

I have also heard recently that Haifa potassium nitrate may have a bit more impurities in it now than what is optimal. I purchased the Haifa greenhouse grade potassium nitrate years ago and it worked well for me. I am now using a USP grade potassium nitrate that I obtained from a manufacturers close out and it is superb. It seems to have a little bit of water left in the product and I remove it by gently heating it in a solar oven for one day.

 

I would also recommend using a hotter charcoal. I use field cured paulownia (Paulownia tomentosa) wood that is retort cooked. The field cured paulownia wood may not seem like a big deal but it does make extremely fast black powder.

 

I would also recommend not using dextrin. I hope this helps.

[Mumbles]

Did you hear about the Haifa thing from a FPAG publication by any chance? I recently saw reference to this myself, but don't have access to the actual article written. Someone had brought this up recently (I think on passfire), but it was unclear if the poster was actually stating something from the article itself or had misremembered.

[SunDevil]

Mumbles,

 

I do believe the information about the quality of Haifa potassium nitrate came from a FPAG publication.

 

I do find it curious that the greenhouse grade worked well for many years. I wonder if the quality was reduced in order to cut production costs?

 

In any case, the potassium nitrate could be improved by simply going through one recrystallization and allowing the product to slowly crystallize out.

I have done this in the past during the winter using distilled water and a large container.

[ChloRure]

Try reducing amount of Dextrin a percent or two and be sure to use distilled water.

 

I always use regular water, would distilled water improuve the final product ?

As for dextrin, I am on the end of my 500g bags (white/yellowish color)... but my other bag is a lot more yellow/brown color, is the the same thing ?

 

Thanks

[pyrogeorge]

No,the water is not the problem.I don't believe that the water can affect.

Try to mill less composition,also the media did they fill the half jar or less?

As for the colour is like cement light gray,not black.In your photo i think that you add more sulphur than 10%.

Are you sure that you didn't make mistake?

Try to make small amount lift powder from mesh screen and compare the result with the pressed granules.

[TYRONEEZEKIEL]

I am very certain that my ratios are correctly measured. My coated rice hulls are blacker than night, and my polverone is black too, but the other stuff that hasnt been highly wetted just isnt black

[pyrogeorge]

Can you tell me please if the media fill the half jar?

The barrel must be 1/2 of media and 1/4 of composition.

[TYRONEEZEKIEL]

Yes the media and charge are perfect to sponenberghs standards. 1/2 jar full of media. charge covers the media slightly. I willl undercharge my next batch a bit and see if there is much of a difference. From the feedback, I really think I need to try using a known hot charcoal to eliminate the charcoal variable.

[Bobosan]

I always use regular water, would distilled water improuve the final product ?

As for dextrin, I am on the end of my 500g bags (white/yellowish color)... but my other bag is a lot more yellow/brown color, is the the same thing ?

 

Thanks

 

I just always use boiling distilled water since you never know what residual chems might be in tap water....especially if you have a whole house water softener.

 

Once wetted enough, let the BP sit for 10-15 minutes before granulating or corning to give dextrin time to fully dissolve and charcoal to absorb KNO3.

 

Your methods may vary but this is what works for me.

 

Edit - Paulownia, Balsa or Willow charcoal are some of the fastest BP charcoals.

Edited July 3, 2013 by Bobosan

[Varmint]

Why is this not perfectly obvious?

 

Corned powder is a raw mix pressed though a screen, and as such is filled with pits, crevices, and exhibits a rough surface texture, all of which contribute to flame propagation.

 

Meanwhile, a pressed cake can be thought of as a piece of glass, when broken up, the "shards" are comparatively smooth on all surfaces, there are few if any voids, and similary, void of fractures and crevices to the extent screened corned material naturally posesses.

 

In other words, the cake material will need to be made finer in order to present an equivalent surface area, but there is a point where fineness no longer pays off, in essence the powder is so intimately in contact there are no channels, gaps, crevices to support flame propagation, and now you are burning slow like rocket BP.

 

The tendancy is to always improve our processes, to mimick industry where practical, to try the new tricks as they come under discussion. The real trick is repeatability. If you can make 10 batches that perform indistinguishably, you have done well. If you are constantly making last minute changes, you are experimenting. Experimenting is fun, educational, and sometimes leads to making meaningful discoveries. But with something like a lift charge, you ought to find what works, and strive to make it the exact same each and every time.

 

DAS

[taiwanluthiers]

I find charcoal makes the biggest difference... I used white pine charcoal a long time ago and it yields not such a good bp compared to commercial. Skylighter airfloat won't yield such good bp either, I think it's made more for sparks.

 

Try willow or paulownia charcoal, they should give acceptable result. Ricing is faster than corning but the grains will not be so durable.

[psyco_1322]

Why is this not perfectly obvious?

 

Corned powder is a raw mix pressed though a screen, and as such is filled with pits, crevices, and exhibits a rough surface texture, all of which contribute to flame propagation.

 

DAS

 

What is perfectly obvious is that you have your terms mixed up. Corning is the pressing of bp into pucks and then braking them up to get the desired size. Granulating is when you take a wetted mix and "grate" or push it through a screen to make granules of powder.

 

5% dextrin will make quite durable powder. If you don't experience that, you are doing it wrong.

Edited September 16, 2013 by psyco_1322

[Varmint]

Psyc0_1322:

 

I'll trade you, Braking for Breaking, Deal?

 

Also, your comments about dextrin have no bearing here, screen granulated powder is VERY different material from corned/broken material, and to get the two to align burn-wise will never be done with the same sized sorting screen. Having said that, corning/breaking is obviously a better controlled path, even a moisture (alcohol/water) different of 1% will have an impact on the granulation process, where corning a consistent formulated and pressed puck will be significantly easier to arrive at the same performance, time and time again.

 

Even a few minutes processing delay or slight surplus/deficit of wetting will make granulation results vary, perhaps wildy, in terms of surface area which = burn rate at the most fundamental level.

 

Ergo, take a proven formulation, of the same volume, and allowing for the same drying time, crush it to the same screening level using identical methods, and you have your best shot at repeatability. A further step to enhance batch-wide performance is to crush the cake to some intermediate value and allow another period of drying. If you avoid this step, the slight mositure elevation near the center of the puck will throw an offset into the process leading to control problems. Once a batch is fully caked/crushed/sorted, the product (properly screened size), if done in batch-wise fashion, should be fully mixed as well.

 

DAS

[Jonathan]

FWIW, I don't press and corn my ball-milled 75:15:10. Just use Dextrin, as you do, to create granules. Previously, I used red gum and alcohol. Both mixes work like flash. The red gum mix is a hair faster by my estimation. The red gum granules are very fine (20 mesh and smaller). Appears as if you're doing it by book, so I have no help to offer. I can say my B.P. is very hot -- too hot for any rocket I've tried except a nozzleless rocket.

[psyco_1322]

Psyc0_1322:

 

I'll trade you, Braking for Breaking, Deal?

 

Also, your comments about dextrin have no bearing here,....

DAS

 

Haha, yeah we will call it even then!

 

My statement of the dextrin was aimed more at taiwanluthiers comment. Saying that granulated powder is not going to be durable is quite misleading.