7 replies to this topic

[AdmiralDonSnider]

A few days ago I prepared a red cut star formula given by Lancaster on page 211: KClO4 70, SrCO3 15, Red Gum 9, Charcoal 150 mesh 2, Dextrin 4

I tested the comp by lighting a column/heap of loose powder but it seemed to burn pinkish orange but not red. Therefore I wondered if watching a heap of loose star composition burn while standing close is an appropriate way to evaluate its colour and performance.
Maybe these have be made into stars and shot into the sky/used in a shell to perform well (burn red). (I remember I read about some "problems" of human eyesight, that colours are not seen as are when standing close, that red seems orange or yellowish when watching the flame longer...)

Not sure, maybe there is something wrong with my manufacturing method or chemicals (e.g. the carbonate which was pottery grade) or everything just went right??

[GalFisk]

Many compositions burn very differently as a loose pile on the ground than as a star flying through the air. 
I tested a loose pile of veline red (which also uses SrCO3) recently that seemed to hardly 
have any red in it at all, but the finished stars burnt with a nice color. The difference is even greater with charcoal streamers, glitter etc which relies on wind and/or oxygen from the air to function properly.
A starmine or star gun is good for evaluating small quantities of stars.

[pyrotrev]

Also, don't ignore the distance factor. Many compositions that look "washed out" when seen close to, actually have deep colour when viewed from a distance - I guess the cones in your retina get over-exposed just like a camera would. As GalFisk said a little mine or stargun used at the correct distance (e.g. 100m in the case of stars for a shell) is the best test.

Edited by pyrotrev, 28 February 2008 - 06:56 PM.

[pyromaniac303]

I think the Lancaster perchlorate based organic red maybe burns a little too hot to give a deep red, the cooling action of it travelling through the air may help this a bit. I find the chlorate based formula (almost identical, but with 1% less charcoal, 1% more red gum, and potassium perchlorate substituted with potassium chlorate) gives a much deeper pure red, as the oxidiser breaks down at a lower temperature. Not that I recommend the use of chlorates for practical devices though.

It still puzzles me that 2 lances of the same dimensions, using both Lancaster organic red comps, burn at completely different speeds: The chlorate burns much faster (and must also burn cooler, to give the clearer colour), and the perchlorate lance takes over double the time.

Test samples were 2" x 1/4" ID
The perchlorate lance burned away in approx 30 seconds
The chlorate lance burned away in approx 11 seconds
(these figures are averages from small batches I made, when testing for a lancework)
Video of the completed lancework is here: New Year lancework

Can anyone explain how the chlorate lance can burn both faster and cooler? Surely the same amount of fuel, burning in less time would give a greater temperature?

Edited by pyromaniac303, 28 February 2008 - 09:57 PM.

[Arthur Brown]

To test a star it must be fired from a star gun. Few stars perform as intended on the ground, likely they will burn slowly or smoulder. Some compositions are grossly under oxidised and rely on moving rapidly through air to burn properly.

A star gun can be thought of as a single shot candle. Some fusing arrangement then some lift then the star, All in a short ish tube of card or metal and safely positioned in a firing ground.

Fire the star and see about it taking fire and burning for the desired time rate and colour. If the test star burns too slowly it may land, so be prepared to have a fallout zone.

[seymour]

Adding a chlorine donor will also help.

[MDH]

Is that solidly the only composition you are willing to work with? There are much better reds incorperating only strontium nitrate, a fuel and a basic chlorine donor which are very red, and very pure in their colour...

[portfire]

If you have MgAl you could try Buell red,that uses SrCO3.Although i haven't used it myself,it's one of the best reds i've seen that doesn't use SrNO3.

Buell Red

Potassium Perchlorate 35
Strontium Carbonate 25
Magnalium 14
Parlon 13
Red gum 7
Dextrin 6

http://www.pyrosocie.......ic=889&st=0

Theres a video of them in action.Maxman's post#9

Dean