14 replies to this topic

[Rhodri]

Just thought I'd pass this one to the forum.

Probably stating the obvious here but.....

Has anyone found that slightly damp BP powder deflegrates a little faster than dry BP?

I made up some BP in the mill - it was almost dry. Ignited a little - it burnt very well.

Milled a little more then dried off.

When I lit the drier powder it too was good but not as fast as the slightly damp powder.

Now when I say damp, I don't mean wet - almost dry - if you squahsed it it would remain in a pellet but would crumble.

I know moisture is an important part of powders but didn't really expect it to be a factor in burn rate.

Maybe something or nothing.

Any comments?

[robert johnson]

Well spotted ,Their is a certain stage when the pb is drying out that it's burn speed increases and then slowes down again when the powdr dryes out,Will find out why for you.

[bernie]

I have also experienced this. The other guys on this forum I'm sure can give you a scientific explanation. Just confirming your observation. Same way with stars/comets that have been moistened with say 6-7% H2O and pressed on an arbor press. At different points in the evaporation process they have different burn charactristics. Cut stars too. But I think some how the two are not related specifically in this instance.
My money is on the liberation/breakdown of H2O molecules during the burning. Just wanted to take a guess. The itty bitty spaces in bp "flour" might matter. I might just go take a look myself.
A little off subject but....I pretty much have the process down but I am curious how Rhodri does his bp. Methodology.A big subject I know. Not all at once or even completely. Some mill KNO3 seperately for a prescribed period then the C&S together for said amount of time. Then put it altogether for a shorter period to incorporate the three. Others put it in(the mill) all at once and ball mill.
A lot of variables exist. When I make bp for lift or the like I moisten to about 3-4% then press thin "pucks" in an arbor press.
After they dry a while I do the corning process and grade.
Mr. Johnson is right on when he states "Well spotted". Nothing beats a good obsevation. Sometimes it's irrelavant. That's hardly ever the case. You always learn something.
Looking forward to the responses of others on the moisture subject.

[fusion121]

Well the all important thing in fast propagating reactions is the surface area of the reactants, in with totally dry black powder you particles will interact less as their tendancy will be to actually keep their distance to (elctrostatic interactions), when slightly moistened water molecules will bind particles together allowing the intial stage of the reaction to happen much faster. Its also possible that the evapouration of the water would create a fine aresol of reactants above the main reaction creating a far faster initial reaction, due the presence of suoer heated reactants in a near gaseous state. Those are my guesses.

[Rhodri]

Sounds plausable fusion!

Let's wait for uncle Rob to explain it to us.

Bernie, I make my standard BP as follows:

Ratio: 75:15:10

I grind KNO3 up in clean coffee grinder.

Add to mill.

I then grind up together the S and C (Willow) in the grinder too (without cleaning out from the KNO3 grind).

Grind for a good 5 minutes.

Add to mill.

Spary warm de-ionized water on the mix.

Load the mill with lead weights (not ideal I know but it does work okish.....)

Mill for 3-4 hours.

Weigh the yield (just for the record to see if I've lost any )

Empty out onto grease proof paper and dry.

Nothing too exciting. I don't compress or corn. I just use the powder as is.

Seems to work fine for lift, report etc.

A while ago Rob provided me with the CIA method - it seems to give slightly superior results - and is no doubt easier to do.

Yet to try it though!

[Edited on 29-4-2003 by Rhodri]

[adamw]

The precipitation (CIA) method produces good quality powder, but it quite a pain to do in my opinion (messing around with alcohol/water mixes) insead of just sitting back and letting a ballmill do the work. Still, its more fun that just buying it.

[bernie]

The CIA method is indeed a bother. The powder form(flour/meal) of bp seems like it wouldnt burn quite as fast as the granulated variety. A surface area issue. More bang for your buck. Consistency
Rhodri, I've heard that some Italian fireworkers use the very same polverone that they use in cylinder shells for lift as well. Its granulated (not pessed or corned)via a coarse screen while wet, held together w/ dex., let to dry then graded for size. When using for lift they make a tightly bound lift bag integrated right into the paste wrap. Mentioned merely for the sake of economy of chemicals.
Charcoal is always the big variable in burn rate. I like to make my own bp. I do not care to make the charcoal. The commercial charcoal I use yeilds results to my satisfaction.
I very much enjoy this topic on moisture in bp. Please continue.

[robert johnson]

Ballmilling works very well if you require a small amount of powder. However if you use a significant amount of BP then it becomes unpracticle to make such amounts.

If you think making BP is abother don't try making an 8" crossette shell because that really is bother.
Regarding lifts as said in much earlier posts I use a form of H3 that is modified for lift that is granulated and bound with dextrin.
The Italians as do the Maltese use pulverone more so on cylinder shells, as you require a weaker lift for the greater efficency of cylinder shells and/or close fitting shells in the mortar tubes , which is why shells use different lifts for different sizes,If you were to replace an 8"shell lift with the same amount as a 3" shell it would most certainly mine or fail very early on.

[Rhodri]

Try not to laugh but this is what I've done.....

Do you know the old tobacco trick? If people roll their own then often the tobacco will become dry after a few days.

The trick to keep you backy moist is to add a few pieces of fresh lemon or orange peel.

Well you can guess the next bit.

I've put 20g of BP into 2 glass jars. Each glass jar has a tight rubber fitting gasket.

Jar A has only BP.
Jar B has BP with some small pieces of fresh orange peel.

On Saturday it will be 3 days since the experiement. I'm going to take 1g samples from each jar and ignite and check burning rates.

I predict that the 'orange powder' will burn slightly faster because of the extra moisture that's been imparted to the powder from the moist peel.

Do you reckon the orange peel will make good 'hulls' for bursting?

I will inform you of the results.....

Am I going mad?

[Edited on 1-5-2003 by Rhodri]

[Edited on 1-5-2003 by Rhodri]

[Edited on 1-5-2003 by Rhodri]

[brocade]

your not just mad your raving mad

anyway its worth ago although if it works how practical it will be i don't no.

[Robbie414]

Plus with the added benefit of a pleasant smell to accompany the show!.....Smellyworks!
It definatley sounds like a good idea, I have mates who swear by the peel in the pouch idea...and you only have to leave a load of peel lying around to see how much moisture it contains by the amount it shrivels up in a short time.
Certainly an interesting one

[Rhodri]

All good comments. Brocade - yes, raving mad.

Robbie, it's good that you too know about the 'backy secret' - citrus peel does have a large amount of water.

TRUE FACT:
Did you know that orange peel, amongst others, contains an organic oil (double bonded alkene) called limonene. If you squeeze a piece of citrus peel into a candle flame there's a good flash - it's because the oil is so flammable.

Anyway, tomorrow is the day when I open my selaed jars and experiment with my organically moisturized powders.

I shall not be able to sleep tonight!

Time for my medecine me thinks.....

[bernie]

Took a quick look in some of the books I have. T.L.davis' book which essentially is an old school text dealing w/ a multitude of explosive materials makes no direct reference in the index anyway to the posed moisture % post. I was disappointed as it is a VERY thurough pc of work. Chances are if you dug around real hard in this text book you would find something.
HOWEVER, Shimizu makes a ref. or two that may prove useful and should at least be taken into consideration for our moisture minded fiend. 1% moisture has best ignition, and most importantly he sites a Amer. Bureau of Mines study(1953) "a curious result in that wet black powder, which contains moisture of less than 7%,is more sensitve than the dry powder(gran. no doubt) to static discharge".Report no.5002. Thats all I was able to find on the subject. another pc of the puzzle. Don't go scuffing around and gathering up elec. on your fingertips you citrus scented fiend. Good advice when working w/ anything that might go boom.
Crikey it's late. My eyes are a blaze w/cathode ray tube emissions. They might burst into flame any second now. POOF

[Rhodri]

OK.....drum roll please.....

Guess what?

Very little difference I'm afraid to report.

My little citrus chums were dired out OK and there was a slight, yet distinctive, odour of orange.

Approx. 1g of each powder was ignited.

Both were very similar is 'whoomph' factor.

I guess I must try some more peel next time.

Then again, I think I should now carry out some 'standard pyro' - back to my wheels.

Bernie, good stuff on the wet powder research. I too have some old books on the subject will dust them off and reply soon.

[bernie]

I'm sorry the whole experiment was ultimately not successful for you. Here in Florida we can't give our oranges away. Had a big crate all ready for shipping to you Rhodri.
For what it's worth ......... study the more traditional methods that have evolved over the last couple of hundred years. I think you will find them to be a bit more focused. If there seems to be a bit of tone in this post understand above all other things in life this one thing.....DO NOT MESS WITH THE WONDERFUL SMELL OF BURNING/BURNT BP COMPOUNDS. EVER. It's just wrong. So as you do not misunderstand, it's been a hoot.