Strontium Sparkler from Skylighter Modification

[Steigede]

I found this guide on Skylighter for some strontium nitrate sparklers. Do anything think I could sub ferro-titanium for the steel powder? Also, curious about the chemistry. What purpose does the Boric Acid play?

 

Strontium Nitrate Steel Sparklers

 

Component: Parts: Strontium nitrate 200 grams

Sparkler-grade (or any other) steel powder 120 grams

Aluminum, bright flake, -325 mesh) 32 grams

Airfloat Charcoal 2 grams

Boric Acid 6 grams

Dextrin 40 grams

+90 ml 25% aqueous ethanol (alcohol) solution

Edited September 5, 2020 by Steigede

[SharkWhisperer]

Ferrotitanium should not present any problems and titanium is super sparky. It will also chew up screens if you try to force it through them. Boric acid is cheap insurance to prevent unwanted exothermic reactions between Al and nitrates, particularly under wet conditions. Instead of powdering it, you can just dissolve it in the water being used to activate/suspend your dextrin binder so it's evenly distributed. You can probably get away with using 0.5% or 1% boric acid instead of the nearly 3% that this recipe calls for. I've never noted an Al/nitrate adverse reaction with uncoated Al and nitrates in the absence of boric acid, but others here have--particularly heating issues, potentially to the combustion point, when wet mixing or drying damp comps. This might become particularly important for comps that are going to be stored for any length of time. If your comp is getting warmer when mixing, you have a potential problem brewing that requires attention. Not neurosis. Not fear. But appropriate attention, with preparation to dump it all into the water bucket if it continues heating up beyond your comfort level or common senses. You're wearing appropriate PPE, right? Doing this in a safe place of course. Have fire-fighting materials at hand (extinguisher and 5 gallon water buckets at minimum)? Cool. You can make sparklers that are a lot more "interesting" than the commercial ones.

 

Personally, I have boric acid but rarely use it with nitrate/Al comps; that said, it is cheap insurance, and at low concentrations probably only minimally affects comp burn characteristics. If you are indeed using bright flake Al, then it is already coated (probably with stearic acid or similar) that allows it to remain shiny/bright--otherwise atmospheric oxygen would immediately react with it and coat it with a layer of grey Aluminum Oxide. So, your Al is already somewhat protected. You can buy boric acid for cheap as cockroach killer at any hardware/big-box store. Read the label. You want 100% boric acid. NOT Borax, which is sodium borate and will screw up both your comp burn rate and color. And definitely not mixed with any other insecticides. Or fireworking chem supply sites sell if for around $4/pound.

[Steigede]

Ferrotitanium should not present any problems and titanium is super sparky. It will also chew up screens if you try to force it through them. Boric acid is cheap insurance to prevent unwanted exothermic reactions between Al and nitrates, particularly under wet conditions. Instead of powdering it, you can just dissolve it in the water being used to activate/suspend your dextrin binder so it's evenly distributed. You can probably get away with using 0.5% or 1% boric acid instead of the nearly 3% that this recipe calls for. I've never noted an Al/nitrate adverse reaction with uncoated Al and nitrates in the absence of boric acid, but others here have--particularly heating issues, potentially to the combustion point, when wet mixing or drying damp comps. This might become particularly important for comps that are going to be stored for any length of time. If your comp is getting warmer when mixing, you have a potential problem brewing that requires attention. Not neurosis. Not fear. But appropriate attention, with preparation to dump it all into the water bucket if it continues heating up beyond your comfort level or common senses. You're wearing appropriate PPE, right? Doing this in a safe place of course. Have fire-fighting materials at hand (extinguisher and 5 gallon water buckets at minimum)? Cool. You can make sparklers that are a lot more "interesting" than the commercial ones.

 

Personally, I have boric acid but rarely use it with nitrate/Al comps; that said, it is cheap insurance, and at low concentrations probably only minimally affects comp burn characteristics. If you are indeed using bright flake Al, then it is already coated (probably with stearic acid or similar) that allows it to remain shiny/bright--otherwise atmospheric oxygen would immediately react with it and coat it with a layer of grey Aluminum Oxide. So, your Al is already somewhat protected. You can buy boric acid for cheap as cockroach killer at any hardware/big-box store. Read the label. You want 100% boric acid. NOT Borax, which is sodium borate and will screw up both your comp burn rate and color. And definitely not mixed with any other insecticides. Or fireworking chem supply sites sell if for around $4/pound.

Thank you! I already had boric acid on hand for making green fire with methanol alcohol. Yes, I'm wearing glasses and use a respirator when mixing dry chemicals. I have not heard of nitrates reacting with aluminum like that. Good info to have!

[Mumbles]

Strontium and barium nitrate are less likely to do that reaction. It's primarily a problem, in my experience, with potassium nitrate, flake aluminum, and some sort of basic modifier like sodium bicarbonate or sodium oxalate. I tend not to use it anymore unless I've had a previous adverse reaction. On a worst case scenario, especially if you have a bigger amount, it can heat up to the point of ignition. On the best case side, it tends to make you unnerved and can partly kill the glitter effect.