Pyroblume Posted January 22 Share Posted January 22 (edited) KNO₃ - CO₃²⁻ Stars Name of composition: KNO₃ - CO₃²⁻ Red Star/KNO₃ - CO₃²⁻ Orange Star/KNO₃ - CO₃²⁻ Yellow Star Composition Type: Color star Creator: Pyroblume Color/Effect: Red/Orange/Yellow The Composition: (by weight) KNO₃ - CO₃²⁻ Red Star Potassium nitrate..............35% Magnesium (40μm)..........20% Strontium carbonate....... 20% Parlon............................... 15% Red gum.......................... 10% KNO₃ - CO₃²⁻ Orange Star Potassium nitrate..............35% Magnesium (40μm).........20% Calcium carbonate.......... 20% Parlon............................... 15% Red gum.......................... 10% KNO₃ - CO₃²⁻ Yellow Star Potassium nitrate............35% Magnesium (40μm).........20% Sodium carbonate.......... 20% Parlon............................... 15% Red gum.......................... 10% Any Precautions/Incompatabilities: Since the mixture contains magnesium, it must not come into contact with water. Precedure/Preparation: This composition is moistened with alcohol and requires an alcohol-based prime. Comments: These mixtures are a way to make colored stars with potassium nitrate. These simply ignite and have a relatively good color. I think that the KNO₃ - CO₃²⁻ orange has worse properties overall, e.g. it doesn't burn brightly enough. A mixture of KNO₃ - CO₃²⁻ red and KNO₃ - CO₃²⁻ yellow, i.e. a variation of the carbonates, would be more suitable. Edited January 23 by Pyroblume 1 Link to comment Share on other sites More sharing options...
AustralianPyromaniac Posted January 23 Share Posted January 23 (edited) A few questions 1) Is there any concern for the corrosivity of NaCO3 + it is very hygroscopic? The star could become wet with high humidity and Mg could react. Binding with parlon + acetone may help this? 2) The level of carbonates is very high. 20% is more than the 15% max recommended. Why did you make it so high? 3) Why is Mg used rather than MgAl? Is the flame temp too low with MgAl? Or the burn rate too low? Or availablity? 4) Did you try with other colors and only these ones worked? Like copper carbonate? Or maybe copper nitrate to increase flame temp? Very impressive what you have managed to do with only KNO3! I think the colours are very nice. Edited January 23 by AustralianPyromaniac Link to comment Share on other sites More sharing options...
Zumber Posted January 23 Share Posted January 23 It seems red is not true red or just washed out. Carbonates works well with perchlorate or Chlorates. Link to comment Share on other sites More sharing options...
Pyroblume Posted January 23 Author Share Posted January 23 1) Sodium carbonate is Na2CO3, I didn't have any problems with corrosion from hygroscopy. The red gum protects the star in a certain way (as if it encases the Mg), so I have no problems even in high humidity. To what extent the use of acetone affects the properties, I do not know. 2) Due to the high carbonate content, in combination with the rest of the mixture, a long burning time is possible. 3) Mg is used, otherwise the star will have too low a burn rate. When using MgAl, the flame temperature is too low and the stars ignite very poorly. 4) Yes, I tried other paints, but they didn't work due to the required flame temperature, so it will be the same with copper carbonate. I don't think much of copper nitrate because of its properties. 1 Link to comment Share on other sites More sharing options...
ThunderEx Posted March 15 Share Posted March 15 I don't think I have ever seen a star comp with such a low oxidizer content at only 35%. Interesting! 1 Link to comment Share on other sites More sharing options...
Mumbles Posted March 15 Share Posted March 15 With the formulas above, the carbonate is also contributing as an oxidizer. It's not common, but it's possible with metallic fuels like Mg or MgAl. 2 Link to comment Share on other sites More sharing options...
Arthur Posted March 16 Share Posted March 16 MOST star formulations rely on some oxygen from the atmosphere. Link to comment Share on other sites More sharing options...
Crazy Swede Posted March 16 Share Posted March 16 (edited) 7 hours ago, Arthur said: MOST star formulations rely on some oxygen from the atmosphere. Really? It is true for secondary effects like glitter or tails, made from excess charcoal and/or aluminium or titanium. For coloured stars, the influence of atmospheric oxygen should be extremely small in my opinion. In this case, as Mumbles points out, the combustion relies on the fact that magnesium is so reactive it can use oxygen in additives we normally see as coolants or retardants. Just as a curiosity, magnesium can even burn in a binary combination with PVC, using the chlorine as an oxidiser! Edited March 16 by Crazy Swede Link to comment Share on other sites More sharing options...
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