Potassium Nitrate Based Colored Stars

[thepyrotextbook]

I know many hobbyists from outside the US struggle to find certain chemicals (usually oxidizers other than KNO3), so I decided to try and fill the void of KNO3 based color stars by formulating some compositions. While they still need tweaking, I have found a working composition for red and green using potassium nitrate as the oxidizer and strontium/barium carbonate as the coloring agent. The composition might seem a little weird, and that's because it is. It currently produces WAY too much slag and is extremely hard to light by itself, but once lit, the colors are pretty good. If anyone wants to help test or reformulate this composition to work better and be more accessible, feel free to give updates on your findings! The composition is as follows:

 

SrCO3 or BaCO3 25% (mixtures of these can be used to create optical yellows/oranges)

KNO3 25%

Si 5%

MgAl 30%

Parlon 15%

As it stands, I realize the high MgAl content and use of Si will still make this composition expensive and less accessible (in addition to the oxidizer being a TINY portion of the composition), but any help to overcome these issues would be great. Just thought this would be a fun experiment to see if it really was possible to make decent colored stars without having perchlorate. Attached is a picture of the red composition in action (pumped star test).

[SharkWhisperer]

Good start, but really worried about blowing blind with that oxygen deficient formulation; I'd imagine you're going to need a hot step-prime and moderate burst to keep these alight. But good start, for sure.

 

Why don't you blow a few stars or comets out of a stargun or mini-mortar, or at least toss them after ignition, to see what the colors look like in motion; it can be night-and-day versus the static ground burn results.

 

Is the silicon really necessary, or is this to try to keep them burning. I could see it in a prime to form hot slag on purpose, but perhaps not best in the main comp?

 

What happens if you reduce the MgAl by 5% or 10%, and substitute that mass with additional nitrate, or split the difference between nitrate and color carbonates?

 

What about a little sulfur to lower ignition temperatures to try to mitigate blind-blows, or could this affect the color?

[Arthur]

As an effort to make a colour formulation without chlor based oxidisers this is a useful piece of work.

[SharkWhisperer]

As an effort to make a colour formulation without chlor based oxidisers this is a useful piece of work.

Absolutely. Nonetheless, would appreciate answers to my queries about priming needs, potential lack-of-need of Si in base formulation, etc.

 

Nice work, Text!! Please let us know your thoughts on existing questions--it might accelerate your comp development.

 

"Colour"? Why waste good vowels without good reason? Hah ha!

[thepyrotextbook]

Alright, so today I will be trying out some of shark's suggestions, both independent of each other and (depending on the results) with each other. My main goal will be to lower the MgAl and increase the KNO3, playing around with other fuels to better fill out the comp. If I can get a better version of the comp, I will test and post the results (once again on the ground) but will also attempt to make / prime some stars for a test in a starmine. They might take a bit to dry but I'll do my best to keep the discussion alive.

[SharkWhisperer]

Alright, so today I will be trying out some of shark's suggestions, both independent of each other and (depending on the results) with each other. My main goal will be to lower the MgAl and increase the KNO3, playing around with other fuels to better fill out the comp. If I can get a better version of the comp, I will test and post the results (once again on the ground) but will also attempt to make / prime some stars for a test in a starmine. They might take a bit to dry but I'll do my best to keep the discussion alive.

You have strontium and barium carbonates; are their respective nitrates also in short supply in your area? Maybe they would be better to use than KNO₃ (though a little more expensive) to maintain colors while upping the oxidizer? Nonetheless, a lot of us are enthused by your experimentation. Take your time & let's see how things turn out!

[thepyrotextbook]

This may sound kind of stupid, but I have all the chemicals needed to produce a really nice red that's also inexpensive (strontium nitrate, potassium perchlorate, various metallic fuels, etc). I just felt like seeing if it was possible to use only potassium nitrate as the oxidizer and various carbonates as the coloring agents - a challenge of sorts. Anyways, I made up 3 other versions of the comp. this afternoon and will get some footage / pictures from a basic burn test tonight (I'll also post the compositions at that time). Daytime testing revealed that the silicon was creating all the slag, and that adding in sulfur definitely helped ignition. It still needed a priming comp to be easily lit, but most stars do so this isn't too concerning.

[thepyrotextbook]

Here are today's tests.

 

[KNO3 "Red" #2]

KNO3 - 40%

SrCO3 - 18%

MgAl - 21%

Parlon - 15%

Sulfur - 6%

 

Almost no slag, but gave off an orange color. I suspect that either the increased potassium or lowered overall heat altered the color.

 

[KNO3 "Red" #3]

KNO3 - 40%

SrCO3 - 20%

MgAl - 17%

Si - 3%

Parlon - 15%

Sulfur - 5%

 

This composition is essentially useless, as it gave off slag just like the first but was even more washed out than #2. It confirmed that the silicon was the issue causing the slag.

---------

Overall, tonight's tests were a bit underwhelming, but I think it gave a decent insight as to why the first composition achieved the best results in terms of color. I have a few more composition variants left to try based on these results, so hopefully those go a bit smoother.

[SharkWhisperer]

Kudos to you for trying low-cost comps when you're not yourself in the poorhouse...others will appreciate your efforts. I do.

 

Keep testing. Keep reporting. Take video whenever is convenient--it helps others ro pick out things you might not notice.

 

Thanks! SW

 

p.s. It's really difficult to assess your burn rates and true colors with stationary stars, on the ground, photographed in a single image. Even a crappy cell phone video would be much more useful; for you and I alike!

Edited March 17, 2020 by SharkWhisperer

[kingkama]

Is your Sulphur added with calcium carbonate?

[thepyrotextbook]

Is your Sulphur added with calcium carbonate?

No, the Sulfur is as pure as it gets. I've been using the same stuff in other color comps and it has no effect on those colors, so I'm certain it doesn't have any CaCO3 messing up the flame color.

[PRANAB]

I tested a batch of red star using the following formula. Stransium Nitrate 50. MgAl 20. PVC 20. S 10. Dextrine +5%. Can any one tell me what prime to be used for those star without chlorate and perchlorate? I am thinking that I will prime it with TT.?? anyone did it anytime??Will it works??

[SharkWhisperer]

Pretty fuel rich, but BP/TT should light that. Maybe add in a little Al or Si to heat things up perhaps? Doubt a step-prime is necessary, but no crisis if it is.

 

Other opinions?

[PRANAB]

Is there any nitrate based blue star formula exist?? Anybody has tried it??

[SKC]

Pranab, you may consider priming that with TT+4%MgAl. Use this prime in moderately coarse.

[PRANAB]

Pranab, you may consider priming that with TT+4%MgAl. Use this prime in moderately coarse.

Okay...

thanks for your suggestions...

[PRANAB]

Here is my red color star test...

Link is

 

https://drive.google.com/file/d/1NTqChA5klyhmr2pSrQ3R-t9razW0y7kc/view?usp=drivesdk

 

Prime with green mix...

Thanks...

[Dylman]

PRANAB, Very nice red color

[PRANAB]

PRANAB, Very nice red color

THANKS...

[Crazy Swede]

@thepyrotextbook, have you read what is already published on this subject?

 

I'm especially thinking about "Nitrate colors" by Clive Jennings-White in Pyrotechnica XV from 1993 and some articles by Ernst-Christian Koch that were published in Journal of Pyrotechnics.

[Jimjimboom]

Im keen on this knowlage kno3 i can get alot cheaper than perchlorate! I think im pretty lucky to get perchlorate at all! In my country it is very hard to get

[Mumbles]

How do you feel about sorta grey? Yellow is probably do able too.

[Mumbles]

I should have provided some more information earlier. Without perchlorates or chlorates, colors tend to be rather difficult. The best choices tend to be barium nitrate based greens, and strontium nitrate based reds. These two types of formulas can be blended to create yellows and oranges by optical colors. They tend to be my favorite types of these last two colors. Sodium based yellows, and calcium based oranges are not very attractive to me. They remind me too much of contaminants and you're really restricted to those particular shades. The optical yellows just give more attractive hues in my opinion.

 

As for potassium nitrate based color stars, your options tend to be rather limited. It just doesn't make a great base oxidant for colors. Reds, greens, blues, and purples are going to be out the window. Other colors can work. As I alluded to, you can make a white star.....sort of. They tend to come out rather grey in my experience. Here's one I've used before:

 

Potassium Nitrate - 59

Sulfur - 30

Meal powder - 11

Dextrin - +5 parts

 

It's not the best. It's white-ish but not particularly bright. It also gives off a rather irritating smoke due to all the sulfur. There are other options containing metals that may be more to your suiting. It's a little hard to get just a white star and have it not be more of a streamer though. Barium nitrate does make some nice white stars too.

 

A better option is one containing antimony trisulfide. It will brighten it somewhat and make it a more defined white. This is one from Davis. It matches well with other organic colors, but cannot really stand up to the brilliance of metallic colors.

 

Potassium Nitrate - 62

Antimony Trisulfide - 17

Sulfur - 17

 

Similarly to the above whites, a yellow or yellow-orange can be made too with a higher amount of charcoal. See below for an example:

 

Potassium Nitrate - 48

Sulfur - 24

Charcoal - 10

Meal Powder - 60

Rosin - 2

(You may also want to include dextrin if water binding)