Fountain / Gerb formula for pushing microstars

[nordicwolf]

Can anyone share their formula for a decent base mix for a fountain that is fairly long in duration yet strong enough to launch 0.25-0.3" microstars? Obviously the nozzle has to be wide enough to let the stars escape, but I am looking for a tame formula that lasts a while yet can still eject the stars.

 

I have learned so far that ball milling a standard BP mix is far too hot for this, burns quickly but high altitude sparks and stars.

 

Things I have tried:

60:40 (no sulfur) ball-milled: has about the energy I think I want, comparable to a commercial fountain I took apart. I decided to granulate the powder using hot water so as to knock down the dust, but I since learned that the hot water really activated that mixture - it is very fast now such that I might try a rocket motor with it

 

60:30 (no sulfur) screen mixed with eastern red cedar, hot water mixed/granulated. This works pretty well but I would like it to last longer

75:15:10 (commercial hardwood airfloat). Powder only, not granulated. This is getting closer, but I don't have a steady supply of hardwood airfloat. Maybe I will try some lump charcoal from walmart and mill that.

 

Things yet to try:

60:40 screen mixed with commercial airfloat (no hot water granulating, maybe just room temp water)

60:40 screen mixed with eastern red cedar (no hot water granulating, just room temp water)

 

What do others use? (hopefully there are some fountain makers out there.) thanks again!

[cmjlab]

I'm not sure what pressure you're pressing them at, but you might try a base mix with more pressure to slow the burn. I've not made a lot of fountains, mainly glitters, but the ones I've made there is a difference between hand ramming and pressing, or pressing them in a sleeve.

 

I'll look around to see what other base mixes have been used though.

 

Charles

[Arthur]

There are hundreds of mixes that have been popular, mostly based on milled and corned BP with additional charcoal sulphur and or nitrate sieved in together. Then of course there is the method of powder compacting used that makes a difference.

 

http://www.thegreenman.me.uk/pfp/fountains.html

 

Much about each formulation depends on the mesh size of ingredients, in the case of the charcoals no-one makes clear reference to the wood used which can make a great influence on the effect.

 

I don't think that the site (it's much bigger than one page) lists a precisely defined mixture with a precise method for anything, largely because when the formulae were shared not everyone wanted to give all their trade secrets and partly because the old hand methods have now largely gone and are not known anymore.

 

HOWEVER the site lists hundreds of formulae which once did work, so unless they have been superseded (cheapened!) should be a basis for research into a good cheap and effective firework.

 

If it says Orpiment or Realgar think carefully who you want to poison, some things were acceptable once!

[cmjlab]

One other thought comes to mind, in the old days if one wanted to alter the power/burn speed of a BP motor, you could either add KNO3 to increase burn speed, or increase charcoal to decrease burn speed.

 

Perhaps if you started with a screen mixed 75/15/10 and added +5% charcoal until achieving the burn speed you wanted. Then you could still wet and screen granulate to keep dust down, while balancing the burn speed you want.

 

Charles

[nordicwolf]

Thanks for the replies! I mainly press (because I have one and tube supports as well.) I have not noticed much difference in speed between when I hand rammed and now when I press, but in all honesty I cannot recall which other variables may have changed, and a fair amount of time has gone by. I have thought to control burn speed as suggested (by adding charcoal to get the speed I am after) but wanted to pose the question in general about it. I also played with nozzle opening - that had more of an affect that I remember pressing pressure did, but I need to do more carefully controlled experiements.

 

@cmjlab: What glitters did you make into fountains?

 

And thanks @Arthur for the link - lots of good stuff! I have no realgar or orpiment so no worries there :-)

[cmjlab]

I've made Millers Gold/Silver (uses bicarbonate instead of Antimony), Gold Tremalon, and recently I've been trying some of the gold/yellow glitters in Clive Jennings-Whites study on glitter phenomenon. I'm partial to the gold glitters with the large strobe like spritzels.

 

"Bright Yellow Glitter"

https://youtube.com/shorts/uaQPUF3hWvI?feature=share

[cmjlab]

I've tried a bunch of Winokir formulas, and the fairy fountain formula Lloyd made. All worked well, it was just a matter of getting the nozzle size right for the respective glitter.

 

I don't think any would work well for microstars though if that's what you are wondering. The gold formulas especially would probably overpower the colors.

[cmjlab]

I recall recently that reading somewhere that anywhere it called for realgar it could be replaced with something more common and still function well (prob not as good as the realgar) but close to it. I'm sure I'll remember some random time and forget why I even cared....

 

Charles

[nordicwolf]

When I experimented with this before...I've found that when using dedicated fountain formulas, it was not so much the gold, say, overpowering the microstars but insufficient "thrust" to eject stars. I have not tried the glitter you recommended but will do so - thanks. I will be trying more fountain-specific formulas with stars just to see how they work.

 

Thank you!

[cmjlab]

I wish you luck! It would sure be a pretty cool fountain to see gold strobes with blue microstars. If you do get it working, I sure hope you share your process, I'd love to make a few.

Charles