can't seem to make decent BP

[Arthur]

You may find it easier to simply allow more time! My little rock tumbler spins at about 60 rpm and takes 8 hours to a fair batch of powder, while my big mill does about 80 rpm and does a batch in 4 hours.

 

BBQ charcoal contains all sorts! Some lumps are better for us than others I have som BBQ charcoal and some lumps crumble by hand and some resist a hammer. Good powder comes from really soft charcoal.

[Mario1]

News update! My BP just came out of the mill. They BP is great for me. Not the best or fastest but puts my rockets up in the sky at least.

[stormyweathers]

my BP is all milled and its super fine

so my method is definitely improved

 

now, im trying to granulate the powder

[ i need to do this to get good lift and burst right?]

 

i start by wetting the powder with a water/alcohol mix untill it has a clay like consistency

 

the i try to pass it through a mesh and catch the clumps

 

however, the grains that form always stick together.

 

any advice?

[Richtee]

however, the grains that form always stick together.

 

any advice?

 

 

It's still too damp. Knead it and form "pancakes", and let dry till they ALMOST crumble. THEN screen.

[Mumbles]

If you are planning on coating onto some sort of carrier, such as rice hulls, puffed rice, etc. you will want to leave it powdered. This is useful for breaking ball shells, and can be used to break some canister shells.

 

If you want to use it as lift, or as a break for canister shells (all sizes), it should be granulated. It's hard to get the right consistency the first time, that is for sure. I wet it until it holds together into a ball, and when broken in half does not crumble. It's hard to explain, it's easier to show.

 

Another trick to getting good sized granules is to regranulate the composition about an hour after the initial time. Roll the comp across the screen, don't press directly down. This will break up larger clumps, but not squeeze them back together. A lot of the granules may be sticking together, but they're not fully stuck. After they're dry, they'll easily break up. I generally re-screen through a larger screen, but that is not available to everyone.

[TheEskimo]

Are you using a binder? It sounds like just plain BP with water. When I overwet my BP, it is very hard to get thru the screen...it just forms a gooey paste that clings to the screen.

[Richtee]

Are you using a binder? It sounds like just plain BP with water. When I overwet my BP, it is very hard to get thru the screen...it just forms a gooey paste that clings to the screen.

Huh... yanno..I missed that...LOL! DOH!

Yes... you should be using a binder. Dextrin is what I used... baked corn starch. Do a search, lots of info on making it. I used around 5% by weight.

[mike_au]

When I started out, talk of "clay like" consistency led me to add far too much water.

 

Now I add about 15% by mass 85:15 water:ethanol and it works nicely.

[Swede]

Adding too much water is a common problem. What happens is that the potassium nitrate dissolves in the excess water, and when it dries, it recrystallizes into larger portions compared to what existed before wetting. Remember, BP is a MIXTURE. There is no significant chemical reaction before burning. Any mixture that is exceptionally fine, and with the components in intimate contact, will perform better than one not as fine.

 

Almost everyone here has made greenmix as a kid that barely ignites, and leaves behind glassy slag that is mostly molten potassium nitrate. The fineness of the mixture out of the ball mill can be ruined with excess water which physically "undoes" what your ball mill did, if that makes sense.

 

A lot of texts recommend alcohol as a "wetting" agent, and it does help wet, but I also think it helps inhibit the nitrate from dissolving/recrystallizing. The dough should look dry and be very stiff. If you squeeze it and see a shiny surface, it is too wet. When you add water + alcohol, do so ever so slowly, and as you get close, use a gloved hand to massage the dough. It'll reach a point where even 2 more ml of water will be too much. Like making stars, it is probably wise to save 5% of the BP as dry mix on the side, so you can correct overwetting.

[TrueBluePyro]

When I have my BP wet enough,,,it still looks like it is a powder, but if you can clump it together without seeing any water, then it is good. you really need to mix the water in for a while, cause it may not look like alot of water, but once you start mixing for a while and get it all over the BP then it may be too much, it sometimes takes a while just to get the right amount of water.

 

After a few times if making BP adding the right amount of water will be come 2nd nature, but for now, it is experimenting and in finding out how much not to put it. You'll get the hang of it.

[Twotails]

I use a mister, a simple spray bottle filled with Alcohol and water(some times Acetone if im in a rush to dry it.) it set it on its finest mist setting, and little by little, mist it. ( for 200g and under batches i fill a 3oz misting bottle, like the kind you would use on vacation IE: travle size)

 

Some times i make my BP into a slurry, shove it in the dehydrator, and re-mill it. I doubt i does anything significant, i noticed no burn rate decrease.

[stormyweathers]

im still having trouble with the moisture levels, but i did test the meal powder.

 

i spent some time trying to think how i could really test the power without granulating, so i whipped up a simple cannon with some buddies and fired some projectiles in his backyard.

 

my powder works as good or better than commercial muzzle loading propellant, which is rewarding.

 

also, if i load any flammable liquid into the barrel, i can get a nice 20ft fire ball easy enough

 

ill try the granulating with acetone when i get the chance

[Mumbles]

Don't granulate with acetone, unless you have an acetone activated binder. It wont do any good, and leave crumbly granules at best. Put some dextrin in there, and use water.

[Richtee]

Don't granulate with acetone, unless you have an acetone activated binder. It wont do any good, and leave crumbly granules at best. Put some dextrin in there, and use water.

Yep...or the water/isopropyl mix. K.I.S.S. has it's rewards!

[stormyweathers]

would it be better to use strait iso?

and i have excess dextrin lying around so i will most likely use it

 

5% by weight right?

[firetech]

Yup 5% by weight.

[Mumbles]

Isopropyl alcohol wont activate the dextrin.

 

In a somewhat, but not really, related note. I was reading on passfire, and Ned was claiming he was getting hard grains with just denatured alcohol. No dextrin, no red gum, nothing not BP. This seems completely unrealistic to me. Has anyone tried and confirmed this?

[NightHawkInLight]

Isopropyl alcohol wont activate the dextrin.

 

In a somewhat, but not really, related note. I was reading on passfire, and Ned was claiming he was getting hard grains with just denatured alcohol. No dextrin, no red gum, nothing not BP. This seems completely unrealistic to me. Has anyone tried and confirmed this?

I used to do just fine granulating my BP with no binder. I milled the stuff so fine it would form a solid mass when simply pinched between the fingers. Just the little bit of strength given by reforming the nitrate crystals when drying holds BP that fine together - at least I assume that is the cause. Now, it's not as strong as when a binder is used obviously, but it takes a good bit of force between the fingers to break the granules. I only started using a binder in my BP when I moved up to larger canister shells that required large granules able to withstand spiking and heavy lift pushing in on the contents of the shell.

[Mumbles]

You tried it with alcohol or water? I can understand the water to some extent, but all of the chemicals in BP are more or less completely insoluble in alcohol. Unless one of the denaturants dissolves sulfur.

[stormyweathers]

i tried with water and acetone, no binder

 

but from what ive read, it seems as the main problem is that its too wet

 

ill try with the dextrin next time

[dagabu]

Isopropyl alcohol wont activate the dextrin.

 

In a somewhat, but not really, related note. I was reading on passfire, and Ned was claiming he was getting hard grains with just denatured alcohol. No dextrin, no red gum, nothing not BP. This seems completely unrealistic to me. Has anyone tried and confirmed this?

 

That was the conversation Ned and I have been having

 

I am leaving for home right now and am going to try the denatured idea tonight. I do disagree with the 5% of dex by weight for BP, it slowed my very serviceable BP down too much so I cut it back to 2% and it was fine. I am currently waiting till Oct to test out lift using other binders like Parlon, CMC, SGRS, and Guar Gum on Vermiculite. I'm using 10 grams on a baseball and timing the entire flight.

 

I you buy rubbing alcohol (70/30) it will activate the dex.

 

I hope my video camera will work so I can post on Pyrobin.

 

Dave

[stormyweathers]

so what pecentage of dextrin should i use?

is there anyone else to confirm or deny that 2% works?

[Seymour]

I can confirm.

[firetech]

Water slows down bp. However it turns out that BP likes a bit of moisture in it. If you throw in 5% you need a bit more water. 2%- a bit less. So anywhere between 2 and 5 should be ok. This is all in terms of granulation. 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.

[Richtee]

Isopropyl alcohol wont activate the dextrin.

 

In a somewhat, but not really, related note. I was reading on passfire, and Ned was claiming he was getting hard grains with just denatured alcohol. No dextrin, no red gum, nothing not BP. This seems completely unrealistic to me. Has anyone tried and confirmed this?

 

True... but does not the alcohol speed the drying time of the amalgam?