273 replies to this topic

[BigG]

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?

Yes, In many cases red gum is used as fuel. And no - you can substitute one for the other. St. Nitrate is known to give very pure red colour while St. Carbonate does not. You can try adding perchlorate and a colour donour - but you will be researching a whole new formula now.

[treefingers]

ok thanks

[The Pyromaniac]

The formulas zanes told just give off stars
I dont understand why do you call it fountain
If this is fountain then 3 formulas of stars which I posted should also be included in the fountains formulas

[portfire]

Hi all . well im pleased to say my first fountain trials were a success, i also achieved a very impressive
catherine wheel after a week of testing.
Here's the fountain
http://img227.images...=pic0117pq8.jpg

The tubes have an ID of 15mm with a 2.5mm wall 100mm long and were rolled with kraft paper (the stuff used to rap percels) and pasted with 50/50 pva/water. The nozzel was 5mm deep/5mm choke and was just rammed powdered kitty litter.
The formula was nothing special,just a fast greenmix with 5% charcoal added and rammed hard.

The funny thing is ,is that when i was testing singal fountains earlier this week (with out the 5%charcoal) they seemed to have a lot of thrust, and with some more testing and a reduced choke to 4mm turn's out i have a very successful driver.
Here's the wheel
http://img440.images...=pic0116qs8.jpg

The only problem with the wheel was as the second driver burned out it came off and flew across the garden ,so in future i'll be securing the alot more.

special thanx to karlfoxman for this picture which helped instant ignition of all three fountains http://karlfoxman.fr...ff/DSC00199.JPG


(update) this is a link to a few more pics

http://my.imageshack.us/v_images.php

Edited by portfire, 27 January 2007 - 10:39 PM.

[karlfoxman]

Glad the picture helps, these are how we fuse our lance work. Works very well and never had a failure, we have fired around 150+ lances like this and not one has not lit. Shows how simple and effective some methods work. Its all one piece of quickmatch and the under side is cut to expose the match, then we tape over and around twice, works a treat. Mine and Wazi's idea so thanks to Waz too! Like your work, they look very nicely made and your making pretty stuff I bet, titanium or ferro titanium adds amazing effects. Also look into making coloured fountains like red with silver sparks. Challenge for you

[portfire]

thanx karl. yes i cut into the match pipe and inserted a peace of match down the pipe and then into the nozzel then caped off as in the picture. as for the effects, i just wanted to get the basic principle right and a good idea of the working procedures first,obviously the next step for me is to add effects now so i accept your challenge
just a quick question,i have'nt made a press yet so is it safe to ram aluminium as it's no sparking?

Edited by portfire, 27 January 2007 - 08:12 PM.

[karlfoxman]

Its not advised but ramming aluminium should be ok, just wear correct ppe. Long sleve jacket (possibly flack jacket like I will have soon!) Face protection like hardhat with full face shield. Good your getting them right first before going onto more ideas, shows good practice. Drivers for wheels are quite hard to get right and consistent but im sure after plenty of practice you will get them right, I might be able to get formulas,milling times and dimensions for them from my friends in Malta (with permission)

[portfire]

I think i'll stick with the basic's for now while i sort a press out,maybe try and get a more dense charcoal spray, but any easy,safe to ram formulas for the time been would be much appreciated.

I totally agree with getting good consistent results first, i would'nt move on until i know that im ready and although iv had success so far the next 5 or so might cato

Edited by portfire, 27 January 2007 - 07:21 PM.

[BrightStar]

Having finally sourced some titanium, I put together a simple gerb for testing this evening:

Fast BP meal (willow) 75%
Hardwood airfloat charcoal 15%
Titanium sponge, mixed 60 to 10 mesh 10%

12g of this comp was moderately pressed into a 1/2" tube with a 6mm clay nozzle:

1/2" titanium gerb test (divx 1,152 KB)

Edited by BrightStar, 30 January 2007 - 02:13 PM.

[Zinginex]

Having finally sourced some titanium, I put together a simple gerb for testing this evening:

Fast BP meal (willow) 75%
Hardwood airfloat charcoal 15%
Titanium sponge, mixed 60 to 10 mesh 10%

12g of this comp was moderately pressed into a 1/2" tube with a 6mm clay nozzle:

1/2" titanium gerb test (divx 1,152 KB)

Hey Nice 1! I've read all of this topic but am i right in saying that when you add metal powder e.g. aluminium to bp for a fountain, treat it with respect as it could be quite sensative to friction etc?

[Creepin_pyro]

Every composition should be treated with respect, but you're right - adding metal powders (especially Titanium) increases the sensetivity of the composition. Any BP-type composition with added metal should be pressed, not rammed. In practise you can get away with ramming some metals, and hand-pressing if you don't own a press, but that's not to say an accident will never happen. I would advise airing on the side of caution - if in doubt, press, and press behind a blast shield.

[portfire]

Hi all.
I'v just tested a fountain with aluminium (300 mesh atomized).As i was only testing i wasn't too bothered about exact ratios. The ratio i used was 8g meal (one hour milled green mix) and 2g Al.

I tested a small pile and the effect i got was white sparks (as i expected) but when used it in the fountain (15mm ID 5mm choke rammed) all i got was yellowy/orange sparks why is this?

Is this somthing to do with temperature,if so how come i get white sparks when its not in a tube but yellowy/orange when its in one,i'd have thought that the flame temperature would be greater inside the tube.

regards
dean

[pyromaniac303]

Maybe because when its in a pile as a powder it all burns at once, which generates enough heat to ignite the aluminium, but when pressed into a tube only a much smaller area is burning at once so the heat may not build up as much.

This does sound strange though, I have no problem igniting anything up to 40 mesh aluminium with my BP...

Is the aluminium coated in anything, or could the comp have been stored, got damp and the aluminium reacted?

[MMMMMM Pyro]

Hi all.
I'v just tested a fountain with aluminium (300 mesh atomized).As i was only testing i wasn't too bothered about exact ratios. The ratio i used was 8g meal (one hour milled green mix) and 2g Al.

I tested a small pile and the effect i got was white sparks (as i expected) but when used it in the fountain (15mm ID 5mm choke rammed) all i got was yellowy/orange sparks why is this?

Is this somthing to do with temperature,if so how come i get white sparks when its not in a tube but yellowy/orange when its in one,i'd have thought that the flame temperature would be greater inside the tube.

regards
dean

It is entirely possibly that I'm totally and utterly wrong about this, but possibly the Al is being burned up in the tube before getting the chance to be ejected as a spark.
What you could do is to ram a smaller one with no choke to see if the problem occurs again, if it does then I'm stumped!

Regards,

Mike

[portfire]

pyromaniac303
As far as i know the Al is not coated,it's 99% pure and from hobbychem.it came monday in a sealed bag and i transferred it straight into a airtight container,and it's stored in a cool dry place.The pile i lit was about 0.5g and took around a second to burn,so it wasn't that fast.

MMMMMM Pyro
I did test it in a 100mm 12mmID unchoked tube (hand pressed) earlier this week and got the same results.This is my reason for my test tonight.

thanx for the replies guys

regards
dean

Edited by portfire, 01 March 2007 - 10:03 PM.