Black powder recipe and method

[Uarbor]

It depends on whether it has an exposed heating element or not.

 

The traditional/safest method, is outdoors screen drying in the shade. Rarely is forced heat drying an actual necessity. Though that doesn't mean it can't be a useful tool, in some circumstances.

The whole point of the accelerated drying time was not my impatience well at least not only my impatience but I read that the faster it dries the less time the potassium nitrate has to recrystallize because of the water in it after you have whetted it. Therefore the potassium nitrate becomes trapped within the carbon. A lot like Heat Treating steel actually. Anyway the powder dried in 4 hours and it is wicked good. Way faster than commercial black powder even 4f. I don't do anything without extensive amounts of research first. And I am used to succeeding on my first try honestly. So when I read about the idea of drying it in a vehicle in the hot sun that sounded like the way to go for the fastest possible drying specifically for the purpose of not forming crystals out of the potassium nitrate and trapping it in the carbon. That's what I was going for anyway before I spilled a gram or two down my defrost LOL. I have a couple of junk vehicles in my field I think that's going to be my new drying place. The only reason I used my truck is because it was in the Sun and they were not. Edited May 21, 2021 by Uarbor

[SeaMonkey]

Hang on to those "junk vehicles" and don't let them deteriorate too much.

 

The demand for "old junk vehicles" to restore is growing and their value is increasing.

 

The better shape they're in the more you'll get for them.

[Carbon796]

I usually try to pull the majority of the water off with airflow first. Then airflow with heat to finish it. The solubility of the nitrate goes up significantly with heat. The less water available when heated, the less nitrate to recrystalize. That's why polverone is better processed boiling hot, and BP cold/RT.

 

That nitrate in the charcoal pores, was disproven many years ago, iirc.

Edited May 22, 2021 by Carbon796

[SharkWhisperer]

The whole point of the accelerated drying time was not my impatience well at least not only my impatience but I read that the faster it dries the less time the potassium nitrate has to recrystallize because of the water in it after you have whetted it. Therefore the potassium nitrate becomes trapped within the carbon. A lot like Heat Treating steel actually. Anyway the powder dried in 4 hours and it is wicked good. Way faster than commercial black powder even 4f. I don't do anything without extensive amounts of research first. And I am used to succeeding on my first try honestly. So when I read about the idea of drying it in a vehicle in the hot sun that sounded like the way to go for the fastest possible drying specifically for the purpose of not forming crystals out of the potassium nitrate and trapping it in the carbon. That's what I was going for anyway before I spilled a gram or two down my defrost LOL. I have a couple of junk vehicles in my field I think that's going to be my new drying place. The only reason I used my truck is because it was in the Sun and they were not.

With the volume of water used to granulate BP (unlike the slurry for making blackmatch), at approximate room temps (+/- a decent margin), there's not a lot of KNO₃ that gets dissolved (see the curve below). Faster drying is not always best; nitrate exists in different crystalline structures/sizes and speed-drying might work against you. The biggest deciders of how your BP works (reliably and reproducibly) are: 1) starting material particulate size; 2) charcoal quality; and 3) intimacy of mixing those comps. Drying variations might have a small impact, but I emphasize small.

 

And please do not designate another vehicle for dashboard drying--don't repeat that mistake. Doors closed and a magnifying glass-like windshield could easily lead to ignition. Maybe when you're walking up to your "safe" car/dryer. Unlikely but possible, and entirely avoidable. Nobody ever expects to get their asses crisped by a batch of comp. Read here about another individual (really bright dude, too) who almost burned his workshop/barn down when a batch of crackle he was sun-drying in a shiny stainless steel bowl went off last year. Some very experienced people have gotten injured in this hobby, compatriots on this site included. You are not immune, but there's a shitload you can do to minimize risk. Except for Darwinian rejects who make match head pipe bombs, when a serious and experienced fireworker gets toasted it is usually not because of overt negligence, but because of bad luck with risks we take all the time. Or a thoughtless slip-up doing something we'd done a hundred times before without problems. And yes, sometimes we make mistakes. Or find ourselves in a hurry and increase risk by cutting corners. But rarely do catastrophes/injuries occur from sheer negligence. This hobby is about risk management, not tempting fate like a teenager. Safety glass or not in your autos, a pound of BP firing up (hotter than Goex, right? Hope so) could turn those windows into shrapnel in the confines of a closed vehicle, even vented with the windows cracked. Could smoke your ass without warning. The lawn/picnic table, or a simple dedicated drying box or safe dehydrator (if even necessary--probably not besides winter), are all great drying places for your BP, but your automobiles, junk or not, are not good places. You mentioned a new pole barn. Bingo! Anywhere away from others, with open doors and ventilation.

 

From below, at room temps (20C), nitrate solubility (perhaps 30 g/100 mL) is only about 7% of solubility in boiling water (250g/100 mL). Meaning, the little volume of water that you add for BP granulation might dissolve a small fraction of your KNO₃, but generally not enough to worry about it. Or to worry about needing to rapid-dry it. Just won't make much of a difference.

 

The problem with your car is that it is enclosed and has a big magnifying glass in front of the dashboard. It is a bad idea to mix/process pyro comps in a car, retired or not. You generally do not need direct sunlight to dry BP.

 

You seem like a thoughtful dude who's willing to learn, but triple-check yourself always when working with energetic compounds. They'll bite you if you let them. Hard. And take care about thinking through the advise or suggestions you get from others, here or anywhere. Yes, I rode your ass for your thoughtless mistake. Because for an apparently bright dude, you did some overtly stupid shit. Yes, I meant to nick you. Wake you up a little. Simply because I don't want to ever hear about our new amigo going to the burn ward. Maybe your public pissed-offedness will lead you towards giving a little more thought to how you approach your new hobby. You can see how Ron and I got along in the early posts, tsk tsk. Now we amuse one another.

 

None of us know everything, but many know a lot. But please check your sources when you get your advice, please, and get second opinions--dashboard drying is just not good advice.

 

Welcome.

 

Edited May 22, 2021 by SharkWhisperer

[MadMat]

Another thing to consider if you are worried about dissolving the KNO3 (personally i wouldn't, but....) Don't use straight water for wetting your milldust, but rather 85% water and 15% alcohol. Adding alcohol does two things: first it lowers the surface tension of the water allowing it to "wet" the powder faster and you will need less added water. Secondly, adding alcohol to the water significantly lowers the solubility of KNO3. IF you use cold water and add alcohol to it, you won't have any problems with dissolving any significant amount of KNO3. You can make your alcohol percentage anywhere from 10-25%, it isn't that critical, but if you are using dextrin to granulate your BP, don't go over 25% alcohol as it will impede the dextrin's binding ability

Edited May 22, 2021 by MadMat

[Uarbor]

With the volume of water used to granulate BP (unlike the slurry for making blackmatch), at approximate room temps (+/- a decent margin), there's not a lot of KNO₃ that gets dissolved (see the curve below). Faster drying is not always best; nitrate exists in different crystalline structures/sizes and speed-drying might work against you. The biggest deciders of how your BP works (reliably and reproducibly) are: 1) starting material particulate size; 2) charcoal quality; and 3) intimacy of mixing those comps. Drying variations might have a small impact, but I emphasize small.

 

And please do not designate another vehicle for dashboard drying--don't repeat that mistake. Doors closed and a magnifying glass-like windshield could easily lead to ignition. Maybe when you're walking up to your "safe" car/dryer. Unlikely but possible, and entirely avoidable. Nobody ever expects to get their asses crisped by a batch of comp. Read here about another individual (really bright dude, too) who almost burned his workshop/barn down when a batch of crackle he was sun-drying in a shiny stainless steel bowl went off last year. Some very experienced people have gotten injured in this hobby, compatriots on this site included. You are not immune, but there's a shitload you can do to minimize risk. Except for Darwinian rejects who make match head pipe bombs, when a serious and experienced fireworker gets toasted it is usually not because of overt negligence, but because of bad luck with risks we take all the time. Or a thoughtless slip-up doing something we'd done a hundred times before without problems. And yes, sometimes we make mistakes. Or find ourselves in a hurry and increase risk by cutting corners. But rarely do catastrophes/injuries occur from sheer negligence. This hobby is about risk management, not tempting fate like a teenager. Safety glass or not in your autos, a pound of BP firing up (hotter than Goex, right? Hope so) could turn those windows into shrapnel in the confines of a closed vehicle, even vented with the windows cracked. Could smoke your ass without warning. The lawn/picnic table, or a simple dedicated drying box or safe dehydrator (if even necessary--probably not besides winter), are all great drying places for your BP, but your automobiles, junk or not, are not good places. You mentioned a new pole barn. Bingo! Anywhere away from others, with open doors and ventilation.

 

From below, at room temps (20C), nitrate solubility (perhaps 30 g/100 mL) is only about 7% of solubility in boiling water (250g/100 mL). Meaning, the little volume of water that you add for BP granulation might dissolve a small fraction of your KNO₃, but generally not enough to worry about it. Or to worry about needing to rapid-dry it. Just won't make much of a difference.

 

The problem with your car is that it is enclosed and has a big magnifying glass in front of the dashboard. It is a bad idea to mix/process pyro comps in a car, retired or not. You generally do not need direct sunlight to dry BP.

 

You seem like a thoughtful dude who's willing to learn, but triple-check yourself always when working with energetic compounds. They'll bite you if you let them. Hard. And take care about thinking through the advise or suggestions you get from others, here or anywhere. Yes, I rode your ass for your thoughtless mistake. Because for an apparently bright dude, you did some overtly stupid shit. Yes, I meant to nick you. Wake you up a little. Simply because I don't want to ever hear about our new amigo going to the burn ward. Maybe your public pissed-offedness will lead you towards giving a little more thought to how you approach your new hobby. You can see how Ron and I got along in the early posts, tsk tsk. Now we amuse one another.

 

None of us know everything, but many know a lot. But please check your sources when you get your advice, please, and get second opinions--dashboard drying is just not good advice.

 

Welcome.

 

and Carbon's probably ready for a new Depends about yet...silly ol' Coloradee granny you!!!

and BetICouldMake that sharp stick fall outta my ass is still at work sorting that out... Best of luck, Prudence!

Thanks for taking the time to make such a detailed response. I am always looking for new things to learn. And I definitely see your point about the curvature of the windshield potentially making a lens.

[Uarbor]

Another thing to consider if you are worried about dissolving the KNO3 (personally i wouldn't, but....) Don't use straight water for wetting your milldust, but rather 85% water and 15% alcohol. Adding alcohol does two things: first it lowers the surface tension of the water allowing it to "wet" the powder faster and you will need less added water. Secondly, adding alcohol to the water significantly lowers the solubility of KNO3. IF you use cold water and add alcohol to it, you won't have any problems with dissolving any significant amount of KNO3. You can make your alcohol percentage anywhere from 10-25%, it isn't that critical, but if you are using dextrin to granulate your BP, don't go over 25% alcohol as it will impede the dextrin's binding ability

I had thought about using alcohol but since it was my first time I decided to follow the Sky lighter recipe which just says straight water. Thank you for letting me know about the 25% limit though I was thinking of using more to speed the dry.

[SharkWhisperer]

I had thought about using alcohol but since it was my first time I decided to follow the Sky lighter recipe which just says straight water. Thank you for letting me know about the 25% limit though I was thinking of using more to speed the dry.

I use 70% IPA (isopropyl/rubbing alcohol) to granulate dextrin-containing granules, with zero problem. I just make sure to leave it sit covered for a half hour or so to allow that 30% of water to access and activate the dextrin before granulating. I don't see any inhibition from the alcohol, but it does take longer for the water to uniformly distribute and contact all the dextrin. Nice hard granules that dry very quickly. And I never use the 5% that many formulas call for, except for some crumbly charcoal-based star comps; for lift, I never go above 2.5% dextrin, and it works fine. The stuff's pretty cheap, so go with what whatever amount suits your fancy, but dextrin is a slow-burning fuel, and burn rate might decrease when increasing dextrin. Probably not a whole lot of different between 2.5% and 5% in BP, but I use less because that's all I need.

 

Without dextrin/binder, I often use 91% IPA because granules dry almost instantly. But it's gotten more expensive and harder to source at Wallyworld since the pandemic. A good substitute is 95% ethanol in the form of Everclear from the liquor store--the rotgut goes for about $10/liter, which is expensive (91% IPA was $2.50/quart at Walmart before covid; still not back on the shelves around here), and some might consider that alcohol abuse. Water's pretty much free.

 

No matter what solvent you use, it can look and feel like it's completely dry and still have a measurable amount of water left in it. A small amount in a ziplock baggie set in the sun will show water release/condensation if it's still wet. I store all my BP in airtight containers with color-indicating silica beads, and usually need to change them out the next day after granulating because they've sucked out the remaining hidden water. Slightly wet BP won't hurt anything, but will cause error in weight measurements. Water is actually added back (a few %) to rocket fuel (no dextrin) to improve packing density when ramming/pressing motors. But for any other non-rocket use, I want my BP weights to be spot-on.

[myfriendtheenemy]

I don't even measure out my IPA and water ratios. I just add in enough water to make it crumbly and add alcohol until it gets dough-like.