273 replies to this topic

[gerritje]

No problem I can get these both, but I first have to order them. When I have got the stuff I`ll post the results.

[gerritje]

Hello i have been testing fountains the height is no problem anymore.I reach 5 or 6 meters with 500 gram of formula. The new problem is when i use charcoal in my fountains the stuff immediately covers the al/mg sparks. Instead of a spray of white sparks i only get a orange spay of charcoal. When i use fine al <50 um instead of charcoal i see the nice white sparks of the aluminiun.

The formula`s i used :

kno3 70
C 15
S 10
Al 20


kno3 80
c 10
s 10
al 7
mg 3

The only formula`s wich work well (produces nice white sparks):

kno3 5
al 2 (mix of course and fine)
s 3

kno3 22
bano3 45
S 11
fine alu 11
coarse alu 11

The al and mg i use are about 0,5/1 mm in size verry course. I rammed my fountains.

My question is what is causing this problem ? The ramming ? Maybe the charcoal is to coarse ?
Please help me this is really anoying!

[fishy1]

i just discovered a nice fountain comp by mistake.

75 kno3
25 sugar
10 sulphur


same comp as a "5 cent sugar rocket", just mixed together roughly, and rammed in an old rocket tube, 1/2 inch ID, about 3-4 inches long.

nice white and blueish sparks, 2m high.

[mussie_electric]

In these many formulas that use Al and KNO3 there does not seem to be much mention of Boric Acid to stop the al/nitrate thing happening and causing potential self ignition... I am here to learn.. does this rule apply only to star formulations, or should we be using a percent or two of boric acid wherever Al and Nitrate (or other oxidisers) come together?

[Frozentech]

In these many formulas that use Al and KNO3 there does not seem to be much mention of Boric Acid to stop the al/nitrate thing happening and causing potential self ignition... I am here to learn.. does this rule apply only to star formulations, or should we be using a percent or two of boric acid wherever Al and Nitrate (or other oxidisers) come together?

I've made gerbs containing Al and KNO3 without boric acid fairly often. The difference between stars and the gerb/fountain comp is that the gerb comp is wetted slightly, then I screen it through 10 mesh and dry it with a fan blowing on it. Once the water has evaporated the reaction won't take place. The dry granulated comp is then rammed in the gerb.

When stars are made, there is more water, and the comp stays wet longer inside the star, with more time for the KNO3 / Al reaction to take place. LLoyd Sponenburgh recommends NOT drying Al / KNO3 under still air in direct sun, which could accelerate the reaction.

Also, I've made up a spray bottle of 25/75 H2O/Alcohol where the water contains 6 gr of Boric Acid per 100cc, and routinely use this solvent in comps containing Al/KNO3 just to eliminate any potential reaction.

[BrightStar]

Wow... I just rammed 1" of dry Chrysanthemum 6 comp into a 3/4" " x 1.5 " tube with a 4.5mm clay nozzle, to test it as a mini-fountain, . It worked brilliantly, with a 3 metre high jet of red sparks for about 3 seconds... Wish I had some pictures... next time... I now have really good silver, gold and red comps for a tri-colour fountain.

I had hoped to use the Chrys 6 as a base for embedding coloured / crackling micro-stars, but it is probably too fast. Any suggestions for a good comp to do this?

Edited by BrightStar, 31 August 2006 - 07:41 PM.

[Valec]

TigerTail works great for me.
Easiest way is to take a bowl of TT, wetting the comp for the micro stars and rub it through a screen in the TT. Dry it and press in the fountain by hand.
No need for a hollow core and a nice high golden plume with lots of stars, for which I recommend metal based comps (strobe is fine, as well as colour stars).

[BrightStar]

Thanks Valec. How do you choke your micro-star fountains? Is a convergence / divergence cone shape needed for the clay nozzle to eject the stars, or will the fast gas flow do that anyway?

[Creepin_pyro]

You have to be slighly careful with nozzles and some microstars. Some will tend to burn up in the tube if an inner convergence nozzle is not formed (this make sense?). Some kinds may work perfectly well with a 'flat' nozzle, but I always form the inner nozzle by ramming it with a rounded dowel - very easy to make, and ensures all those micro-stars make it out of the tube... I think this effect is exagerated when the fountain is not lit upright (like as part of a set-piece), but I'm not sure what the difference is with different types of stars though...

I recently saw some commercial micro-star fountains which employed a crimped, flute or organ-pipe like nozzle, just formed out of the end of the tube, which seemed to be waterglass-treated. This was above what looked like a standard convergence / divergence nozzle. These fountains made a unique, (at least I never heard any pyro make it before) weird sputtering noise which I couldn't work out, so that's why I had a closer look at them. I plan to try and recreate the effect soon.

[Valec]

Typically, I do not use a convergence nozzle.
I take Feinmakulatur (don't know what it's called in English; It's a cellulose powder used for structuring walls etc. before painting them) and mix it with waterglass. This gives a strong dough which fill into the tube to form a nozzle.
It shrink's a bit upon drying, but it becomes incredibly strong and may even be used for several times - that way, I can refill the tubes for about 5 times without making a new nozzle.
And there are no problems with micro stars. Maybe the shrinking makes ist a bit convergent (difficult to check, as it's burned and completely black in the tube) - the nozzle just should not be to narrow, about 8 mm for a 25mm ID fountain with the describes mix works well.

[treefingers]

I've read through this thread and searched this site and the pf data base but I can't seem to find any simple coloured fountain forumlas with out using chems such as Colophonium and Stearic Acid acid. Do you think a star formula with out a binder i.e. KClO4, PCV, Al mix with SrCO3 or copper oxide/carbonate, added to some of the previous forumlas would give a nice red/blue?

[karlfoxman]

Are you wanting purple flares?

[treefingers]

Sorry if i wasn;t clear but I was asking whether adding say a red star forumla minus the binder to a normal fountain mix would keep the same effect, except change the colour. I just said red or blue because the colourants I have are strontium carbonate, copper carbonate and copper oxide. Im not looking for any colour in particular just geneal coloured fountain formulas.

[Creepin_pyro]

Joel Baechle's 'Pyrocolour Harmony' has a section on coloured gerbs. The following link was posted on Passfire not long ago, and mentions Baechle's text:

http://paraphysics.c...sswick_gerb.jpg

This should give you a good idea of what kind of star compositions work best. If you're going to try using other star formulas in gerbs, I would look for ones with coarse metal of some kind. Make sure you press, NOT ram - no coloured star/gerb composition should be rammed.

Edited by Creepin_pyro, 11 December 2006 - 11:36 AM.

[treefingers]

Excellent thanks. A couple of questions though. I noticed each forumla requires red gum but why is this? Surely Gerbs do not require binders, or in this case does it act as a fuel?

Also apologies if this has been asked before but generally in formulas is it ok to substitute Strontium nitrate with strontium carbonate? I know Strontium nitrate is an oxidiser so doing so, would it require you to alter the proportions of the other chems i.e. increase the amount of perchlorate?

Edited by treefingers, 11 December 2006 - 03:25 PM.