153 replies to this topic

[lord_dranack]

I have seen several formulae that mention "hemp coal". I assume that this is charcoal made with hemp. It might be interesting to try to make some from hemp rope or string.

[dfk]

Im replying just to let you all know

Using grapevine, I made some of the fastest MP I have seen yet.
Im going to name drop because I am mad but I was origionaly using charcoal I got from firefox. dont know what it was. Previously I couldnt even get a rocket to fly unless I put my powder through a 4 day process of wetting and milling(so much wasted time).

I threw a small batch of grape Meal P together and milled for just 24 hours, it literally smoked my previous batches.
I do have to say, even though this(firefox) charcoal was inferier I got my meal powder to burn at pretty decent speeds so I can't wait to make some stuff with my NEW meal.

Marcus

[alany]

That's weird.

I can get unspecified (probably pine) lump BBQ charcoal to work just fine with 2-3 hours of milling. It comes out a talcum powder fine meal, grey in colour and burns rapidly with a poof. If you press and corn the meal it will burn with a loud woof, and a somewhat quieter one for just pulverone (+5% dextrin, granulated to -20+40 mesh).

It definately burns quicker with superiour charcoal, but this lump stuff works great for propellants other than lift, and as lift in a pinch - just use more. Even the worst charcoals seem to burn well enough for rockets.

That said, Firefox may as well be called "Liarfox". I've had nothing but negative experences with them, unanswered email, confusing email messages, bizzare 'stock shortages' right after emails telling me they would ship stuff. I've given up on them entirely. If only Skylighter carried the few odd things Liarfox does that I want...

[lord_dranack]

when I contacted firefox about shipping to the UK, I got a reply saying they can't ship to Canada!

[bernie]

Please forgive me if this is an unfounded rumor but I heard somewhere that Firefox was up for sale. It's worth noting that U.S. suppliers sometimes won't answer requests from 'outside'.

[dfk]

I add a little water and it either all turns doughy (and just clumps around in the mill) or it is completely liquid and when I dry it the KNO3 recrystalises in patches

I've never had any luck milling a dampened comp. Tried various % s and it always got gacked up.

Sorry to jump backward but I thought I'd throw my five cents.

Milling wet is how I got my crapy charcoal to make decent Meal, so i know its possible. I know this wasnt your guys problem but ill explain anyway. It gives the diluted kno3 a chance to soak into the charcoal as well as acts as lube causing more motion and a quicker milling time: or rediculously fine finish product.

In my mill I would add enough water to make a slury, the same consitancy as for black match then mill for a day.
I would then spread out to dry in an old bowl, once dry I would mill for another day.

this gave me meal good enough for anything. My result was a much darker powder that burnt quick and clean with a nice burn trail.

This is compared to not doing this process(milling DRY for two days) wich would result in slow uneven burn with slag and residue left behind.

figured I would post, this process helped me through slow times.

Marcus

[pyrodude]

can activated carbon be used beacuse of the large surface area

[bernie]

A couple of days ago back in Aussie pyrotechnics someone brought up paper bark trees. It got me to thinking so I ran out today and pulled the bark off a 'donor' tree. It ain't your typical bark. Looks just like thin sheets of balsa wood. No chopping or cutting. Just wad up rolls and shove it in the can.

After cooking up a very small sample batch I noticed one very nice characteristic about the charcoal. There's no lumps to crush. A few minutes in the mill was all it took to produce airfloat. Will post any promising finds.

[bernie]

There are no promising finds. The upshot is that I saved you aussies the trouble. Instant airfloat. Knew it was too good to be true. Think I'll just green up a bush or two.( I do have some small pumped stars that need to be launched but little is expected )

[Rhodri]

Hi Bern

What was the result of the C? Did you make up some BP with it?

Was it superior or inferior to say BBQ or Pine C?

I must admit - finding sources for charcoal is a bit of an obsession for me!

The 'silver' peel from Silver Birch has always inspired me. It's very flammable (must have high H:O ratio) but I've never harvested enough for even a small batch of BP.

Maybe tree bark would add that certain 'orange spark' to rocket BP? Maybe 10%? In which case small batches of bark would serve more as an additive than major component.

[lord_dranack]

With the bark from silver birch, you can extract an oil/tar by heating it in a sealed can. Apparently the russians in WWII used to mix it with PE and use it as skin ointment!

Edited by lord_dranack, 11 February 2004 - 08:02 PM.

[bernie]

Didn't want to go through the trouble of milling for hours and then corning. Figured that milling for about an hour should give me an idea of what it was like. Also milled another batch with commercially available airfloat for comparison. Pumped three small comets and riced the remaining comp so it could be rammed into a tube for timing.

Set fire to a line of riced 'bark' comp dribbled on a scrap of paper. Same w/ the airfloat. The latter burnt approx. 30% faster. I really don't think it will have much merit as a spark producer either but I'll shoot the comets anyway and then make a brief report.

[Phoenix]

BigG said,

QUOTE (Phoenix @ Feb 13 2004, 05:39 PM)
My 40mm can shells (about 45g) take 3.5g of milld and pressed BP to lift them to about 25m (I think - I use a 2.5 second fuse and they break just before they arc over). 40mm round shells (about 16g) take about 2.5g to do the same. The mortars are about 35cm long.

Thats using home made BP!?!? Amazing. I would never dream on getting insert shells 25 meters in the air using 3.5 grams of anything... More like 10-15. What procedure do you use to make the BP?

Thanks :-). The BP was made from:

Potassium Nitrate.....70
Willow Charcoal.......20
Sulphur...................10

As you can see, the formula deviates slightly from the standard one. I have noticed no difference in burning speed between them, but I'm _really_ stingey with potassium nitrate. Perhaps, though, this formula generates more gas than normal, producing CO instead of CO2?

The willow charcoal was made from salix viminalis, aka osier. The branches were between 0.75 and 1.5 cm thick, and cut in late spring. They stripped of bark, air dried, then cooked in the kitchen oven at 150 degrees centigrade, until they stopped steaming. They were then packed in a biscuit tin and cooked until they stopped venting volatiles and were completely black and crunchy.

The ingredients were milled dry for about four hours, then dampened with 10% de-ionised water, and pressed in a 37mm diameter die (40mm pvc waste pipe) under 1-1/2 tons of pressure. I load 50g at a time, and I think - (though I can't really remember) the pucks are about 35mm long after pressing. I've never actually measured the density of one, but based on this they are about 1.15g/cc. Will do next time.

I then corn them into <0.75mm, 0.75-2mm, and 2-4mm. The <0.75mm is used for cracker fuse, mostly. The 0.75-2mm is what I use for these small shells. They don't really seem to lift too hard. I have tried using 5g of this powder to lift them and then they do just SLAM out of the mortars - too hard. With the coarser granulation I have to use more to get the same height, which means they lift as hard anyway. I have only fired one 70mm shell, but that I used 20g of the 2-4mm stuff for that.

I notice that "The Chemistry of Fireworks" suggest the use of only 4g of BP to lift a 2" shell to 90m. That seems a little hopeful to me.

The BP was enclosed in a lift cone made from two turns of wall paper, which was then attached to the bottom of the shell wit two turns of recycled kraft, wrapped and cut into strips, then layed down onto the cone.

My BP does seem to be quite a lot faster than any of the BP I have found in consumer fireworks, and also it seems to burn faster than the video of commercial 4F on Matt's site (assuming the video isn't slowed down or anything). I don't really know why it is so fast. My procedure for making it is much the same as anyone else's. Therefore I guess I'm going to get pyrotechnic pilgrims coming from far and wide to see my magical willow tree :-)

[pyrodude]

I have an old cast iron burner which the logs go in the top and it burns using coal underneath. Would this be useful to make charcoal in???

[PanMaster]

I have much experience in the charcoal department. I have made many batches and I can say willow charcoal has easily been the best with little effort to improve it. I make charcoal by first getting a good pot to hold the fire and surrounding it with a decent number of bricks. I then get out the hatchet and chop up some planks or logs that are as dry as possible, get a good fire going with kindling until it starts to create lots of red hot embers at the bottom. I then pile a layer of small lengths of wood over it and put a sealed tin full of willow on top. The wood under it will burst into flame creating a great heat. an appropriately sized tin will carbonise in under an hour.
Why not have competition for the fastest BP?

Edited by PanMaster, 21 February 2004 - 10:12 PM.