1st attempt at making black powder

[Norwest]

Hi,

 

Made my first attempt at making black powder. I first milled the potassium nitrate for 4 hours in a ball mill. I then blended sulfur, air float charcoal (commercially sourced) and dextrin and milled them for 4 hours. I mixed the mixed the milled oxidizer and fuel mix and processed through 100 mesh screen 3 times. I then added hot water to make putty to granulate but messed up by adding too much water. What I ended up with was a slurry. I poured the slurry into a sieve lined with a large coffee filter to remove some water. This seemed to work but I did see some potassium nitrate go with the water and start to crystallize on the table below the sieve. When powder dewatered enough to have a putty like consistency I forced it through a 8 mesh screen to granulate. I set it out to dry and then ran it again through 8 mesh screen. I did a burn test which is shown in the video at the link below. Based on the video the powder burned 20 inches in about 2.3 seconds. Do you think this would work to lift a small mortar round or rocket? Will add water much slower next time so I don't make a slurry again. Will also try making some home made charcoal.

 

Norwest

 

 

https://www.dropbox.com/s/u8yrupyt46n4tmg/video%20sep%2014%2C%2012%2036%2046%20pm.mov?dl=0

[Mumbles]

Based on what you described, I'm somewhat surprised it burned as far as it did to be honest. Less water, or at least less nitrate extraction, and a good charcoal will all help. It's still faster than many achieve on their first attempt.

 

If you overwet again, you can leave it out in a shallow bowl and the water will evaporate. Stirring or kneeding every so often will help speed things up, and prevent the nitrate from crystallizing out too as large crystals. If you have it handy, dry comp fixes everything.

 

That said, I think you'll be okay for rockets. Small shells are a maybe. You'll never know until you try I suppose. Small shells tend to be less forgiving of slower lift. If you have the space, you may want to try launching a small dummy shell. At the worst, it should work for burst. The pressure generated inside a shell tends to make up for slightly slower compositions.

[Arthur]

10% water by weight may be about right, add less initially then let the mix even out and add a little more as needed. Using hot water risks the dextrin setting rock hard very quickly.

[Maxim]

I agree with Mumbles.

Do not use hot water, it dissolves KNO3 better. You dont want to pure the water into your BP, its a lot better if you will spray the water into the BP and mix it with your hands. You should water it until BP turns into a rockish looking stone when you squeze it. I like to add 2% of dextrin to my BP. Does pretty good. I use about 2 mm screen to granulate the BP. And the first thing you want is a very good charcoal.... I do not what types of trees you use for making BP-charcoal in USA, but in Russia the best charcoal are made fron these trees:

Alder tree

Willow ( the best )

Linden tree.

Before ballmillng the comps you want them as dry as possible, or else they will stick to the sides of the ballmill.

And the last thing, you want your BP to be mixed together in the ballmill, the screen will never mix the BP as good as a ballmil can. You should use wooden or plastic cylinders for that, because the metall balls can ignite the BP ( rarely, but with a very good BP and a very big ballmill it may actually happen ).

Welcom to the world of the homemade fireworks comrade:)

Greetings from Russia.

[MadMat]

I agree with Maxim, just screening your ingredients together doesn't quite do it. I always mill everything together.

Also, I've given up on using any binders in my BP, they all slow the burn rate to some extent. I made a press cylinder out of 2" PVC pipe and cast two pistons out of polyester resin (fiberglass resin) right in the PVC pipe smeared with vaseline. With this setup you can even press your mill dust with a big C-clamp ( not the greatest but it works!). I just lightly dampen the mill dust with a spray bottle with 80% water/ 20% denatured alcohol (among other things, adding alcohol helps inhibit the KNO3 from dissolving) and press away. BTW I make home made charcoal out of willow. I did some testing and it makes much better BP than airfloat.

Edited September 15, 2015 by MadMat

[Norwest]

Thanks for all the info and suggestions. spray bottle seems like a good idea. May have misinterpreted the formula/instructions for this prep. I will calculate water by weight percent. Have decided that based on my the limited slace in my back yard and adjacency to neighbors I will not ballmill complete BP mixes. I am intrigued by the challenge to make BP suitable for most lift and burst applications (not talking 6" shells or anything like that).

Wondering if compression over dextrin and wetting is better for "sifted BP"?

As for charcoal wood sources we have tons of alder around and much is available due to a big storm. I do have a honey locust tree in my back yard which I have to frequently trim. Wondering if this hardwood species makes good BP? It has beans which the Native Americans made a "honey" from. Not sure if a resiney wood like this makes good BP? Guess I can compare to airfloat and alder charcoal with honey locust.

 

Tanks,

 

Norwes

[Maxim]

Well 2% of Dex will not do anything bad to your BP. Burn-speed does not matter that much for shells. The harder the wood - worse it is for BP. You hve plenty of Alder? Good, collect a lot, you are gonna need it. The hard wood is good for fountains and rocket fuel.

[Mumbles]

Alder will probably make great, fast BP. The honey locust is pretty much the exact opposite end of the spectrum. It burns pretty slow, but it does make gorgeous long-hanging sparks. They may actually be too long hanging in some instances.

 

You can make acceptable BP without milling everything together. I commend you for considering all the factors when making your decision. You may find you need to use a little more than others, but that's just something that comes with this method.