16 replies to this topic

[EnigmaticBiker]

Hello,

I've just made an calcium sulphate/KNO3 based fountain using Al and a small amount of Mg to increase burn temp. Unfortunately, the expected deep orange colour did not appear, I guess it could have been washed out by the Mg or needed a Cl donor.

Assuming that KClO3 or KClO4 would produce a better colour (and omit the Mg) does anyone know much about this?

Net search did not reveal any info re oxidising behaviour or incompatabilities, except a very brief mention of Al in a data sheet. My CaSO4 was processed to remove water and was probably a mix of anhydrous/monohydrate so little chance of reaction with metals.

Seems like a cheap safe oxidiser.

Does anybody know more?

[completebeginner]

I only know that sulphates and chlorates don't mix

[Frozentech]

Hello,

I've just made an calcium sulphate/KNO3 based fountain using Al and a small amount of Mg to increase burn temp. Unfortunately, the expected deep orange colour did not appear, I guess it could have been washed out by the Mg or needed a Cl donor.

Assuming that KClO3 or KClO4 would produce a better colour (and omit the Mg) does anyone know much about this?

Net search did not reveal any info re oxidising behaviour or incompatabilities, except a very brief mention of Al in a data sheet. My CaSO4 was processed to remove water and was probably a mix of anhydrous/monohydrate so little chance of reaction with metals.

Seems like a cheap safe oxidiser.

Does anybody know more?

I only found one amber colored star that use it, and 2 strobe comps. Winokur Mag Amber, which has more Mg Fuel than CaSO4 oxidizer. It is refererenced as a high temp oxidizer. In the 2 strobe comps, it's a coloring agent, with an Ammonium Perchlorate oxidizer.

From the scarcity of comps, I think perhaps the high temps wash out colors, so it's not much used.

[EnigmaticBiker]

I only found one amber colored star that use it, and 2 strobe comps. Winokur Mag Amber, which has more Mg Fuel than CaSO4 oxidizer. It is refererenced as a high temp oxidizer. In the 2 strobe comps, it's a coloring agent, with an Ammonium Perchlorate oxidizer.

From the scarcity of comps, I think perhaps the high temps wash out colors, so it's not much used.

Thanks for that, I suspected there was a reason why it wasn't much used, other than orange being easier with Sodium.

Given the high temp colour wash out, I can reasonably assume other sulphates will have similar properties, a pity as I had a range of experiments sketched out.

Might be worth using as a drying agent with hygroscopic chemicals though, so I'll roast some more.

Simon

[Damp Squib]

Not sure about your about your comp,but for deep orange have you tried sodium nitrate\charcoal 70\30?

[EnigmaticBiker]

Not sure about your about your comp,but for deep orange have you tried sodium nitrate\charcoal 70\30?

My composition was:-

CaSO4 (ball milled) - 32g
KNO3 (ball milled) - 6g
Al (paint grade) - 12g
Mg (~200mesh) - 0.5g

The oxidisers were milled together for an hour. then the Al and Mg mixed in on paper.
Predictably, the comp was a REALLY dry, free flowing powder.

It takes a fairly high temp to get going but then burns very vigorously . I will try again omitting the Mg and upping the Al.

I was looking for a really cheap, safe, storable fountain base mixture to which I could add stars/metals.

Not tried Sodium Nitrate/C but Sodium Chlorate/sugar burns well , too hygroscopic to store though.

Simon

[Yugen-biki]

EnigmaticBiker

First of all, you can not make any color with KNO3.
Matallic fuel is frequently used with potassium perchlorate.
The Al and Mg will not wash out the color, useing potassium perchlorate.

Your composition looks more like a sulfate flash slowed down with some potassium nitrate. And there for the vigorously burning composition.

I am quite sure you will have no luck getting this, or similar, compositon to give orange color usable for stars.

I have used CaCO3 in orange peony stars with good results. I'm not sure why it is not used very often, but it is probably because you can get a better/adjustable orange useing Sr+Na. CaSO4 is probably not used because you can get much better results with other chemicals.

So you'll need potassium perchlorate and a chlor donor to get some colors.
-"How about potassium chlorate?"
All chlorates are sensitive to friction and/or shock when mixed with a fuel.

Edited by Yugen-biki, 14 February 2006 - 06:32 PM.

[EnigmaticBiker]

EnigmaticBiker

First of all, you can not make any color with KNO3.
Matallic fuel is frequently used with potassium perchlorate.
The Al and Mg will not wash out the color, useing potassium perchlorate.

Your composition looks more like a sulfate flash slowed down with some potassium nitrate. And there for the vigorously burning composition.

I am quite sure you will have no luck getting this, or similar, compositon to give orange color usable for stars.

I have used CaCO3 in orange peony stars with good results. I'm not sure why it is not used very often, but it is probably because you can get a better/adjustable orange useing Sr+Na. CaSO4 is probably not used because you can get much better results with other chemicals.

So you'll need potassium perchlorate and a chlor donor to get some colors.
-"How about potassium chlorate?"
All chlorates are sensitive to friction and/or shock when mixed with a fuel.

Thanks for your detailed reply.

I'm not really aiming to make stars yet, it was more an experiment to see how useful (relatively safe and inexpensive) sulphates could be as a base formulation for fountains, cones, etc. Other suitable sulphates might then be substituted.

Surprised to hear of a sulphate based flash, may discuss that on another thread.
As mentioned below, I intend reduce or omit the Mg, which was only added to aid ignition of the CaSO4.

Perchlorates would of course make better colours I agree, but relatively expensive/toxic compared with most sulphates; Would a Cl donor such as PVC work with such a mixture?

I need to compile some tables of decomposition/ionisation temperatures and look further into the role of Cl in colour production, to help me formulate mixtures more precisely.

Simon

[Yugen-biki]

It is allways best to use a composition that someone has allready tested. There are a bunch of formulas on the net and in books. And if you don't find a formula with the chemical you would like to use, it is probably because it can not be used.

Potassium perchlorate is relatively non toxic. There are much more toxic pyro chemicals in use today then perc. But it has the disadvantage of haveing a relatively high price.

[Damp Squib]

I have never had any problems with sodium nitrates hygroscopy,I have yet to see any noticable difference between it and kno3 if the finished devices are stored in an airtight container as with any other device and stored in a warm non damp enviroment,I guess the only reason it isnt used more frequently in fireworks is due to storage times running into years and the many different locations the fireworks will be stored

I think long term storage of any home made device is a bad idea but I see no reason a sodium nitrate device wouldnt keep for a year or so,I have fired sodium nitrate rocket motors months after construction with only the motor case for protection while sitting on a shelf in a damp shed and they worked flawlessly

[EnigmaticBiker]

I have never had any problems with sodium nitrates hygroscopy,I have yet to see any noticable difference between it and kno3 if the finished devices are stored in an airtight container as with any other device and stored in a warm non damp enviroment,I guess the only reason it isnt used more frequently in fireworks is due to storage times running into years and the many different locations the fireworks will be stored

I think long term storage of any home made device is a bad idea but I see no reason a sodium nitrate device wouldnt keep for a year or so,I have fired sodium nitrate rocket motors months after construction with only the motor case for protection while sitting on a shelf in a damp shed and they worked flawlessly

I meant the Sodium Chlorate/sugar mix I briefly tried.

Surprised that the length of storage in a damp shed, although I don't store fireworks for any length of time, so little experience of that.

Sometimes I may store colour/fountain mixtures that don't contain metals, hence the idea of using oxidisers that require a higher ignition temp and CaSO4 for it's drying properties.

I'm very cautious when formulating unusual (new to me anyway) compositions, taking account of incompatible and sensitive combinations.

Working them out from scratch is almost as much fun as watching them burn.

[Damp Squib]

I use sodium nitrate frequently as it is cheaper and more readily available it has almost the same properties and potassium nitrate,Nano3 is 'slightly' more hygroscopic and slightly more reactive than kno3 due to it releasing 25% more oxygen per weight than kno3,its pretty useless in colour comps due to the deep orange drowning out other colours but hence good for orange,the colour can be controlled simply by adjusting the heat of the reaction the higher milling time or less charcoal will heat up the reaction until the flame becomes white

As far as my research has taken me nano3 has the same Do's and Donts as kno3

But hey whatever works for you ,good luck with your Orange comp

[EnigmaticBiker]

I use sodium nitrate frequently as it is cheaper and more readily available it has almost the same properties and potassium nitrate,Nano3 is 'slightly' more hygroscopic and slightly more reactive than kno3 due to it releasing 25% more oxygen per weight than kno3,its pretty useless in colour comps due to the deep orange drowning out other colours but hence good for orange,the colour can be controlled simply by adjusting the heat of the reaction the higher milling time or less charcoal will heat up the reaction until the flame becomes white

As far as my research has taken me nano3 has the same Do's and Donts as kno3

But hey whatever works for you ,good luck with your Orange comp

Sounds like a neat way of producing a deep orange without getting too technical (as you've possibly noticed I often do )

Wonder if there is a table of how hygroscopic various things are.
I could compile one if I can find the data.

(there I go again )

Simon

[seymour]

Sodium nitrate cheaper than Potassium nitrate? Hah! Where do you get your Nitrates from? Sodium costs about three times Potassium nitrate where I get it, and my supplier was not hard to find. As fars as hygrscopicity goes, My experience shows that a comp containing KN and Sucrose will become damp over time, while with Sodium nitrate you will get a puddle...

On another note, I too use Sodium nitrate "fairly" regularly for rich Yelllows and golds, though I must be ALOT more careful with the choice of fuels than with the Potassium salt if I do not want a pile of mush.

[mussie_electric]

It is allways best to use a composition that someone has allready tested. There are a bunch of formulas on the net and in books. And if you don't find a formula with the chemical you would like to use, it is probably because it can not be used.

Potassium perchlorate is relatively non toxic. There are much more toxic pyro chemicals in use today then perc. But it has the disadvantage of haveing a relatively high price.

Hi Yugen - Just out of interest, what handling precautions do you use for KClO4 - when you say 'relatively non toxic' I was just wondering. I have seen info that suggests this chemical can cause seriuso blood disorders and is a cumulative toxin. I'm not picking an argument so please dont think so! Its just that I have recently acquired some of this and want to be certain that I (and everyone) know how to more safely use it!

Thanks!