Air Float Charcoal Black Powder

[Mumbles]

My understanding of yellow powder is that it needs to be melted together first to prepare it before it takes on it's full characteristics. I'm still not sure what is formed, but based on the color changes it undergoes, I'd suspect some sort of complex polysulfides are formed in the process. I don't think ash is going to offer any beneficial effects in this regard.

 

The ash thing is becoming more in the public consciousness. Commercial airfloat has quite a bit, measuring upwards of 15-20% or higher. Some places in europe have come up with the same solution as David mentioned. A higher proportion of charcoal to help make up for the lower charcoal content from things like vine charcoal. I regularly see ratios like 70:18:12. I wouldn't be totally surprised if some other common burst formulas might be made a little more powerful by tweaking the ratios up or down. For instance, to the best of my knowledge both H3 and KP were developed with hemp charcoal. Hemp is a little ashier and probably has a higher silica content. Someone with a keen eye may notice that the ratio for KP burst is also 70:18:12. Potassium perchlorate and potassium nitrate have effectively the same oxygen content actually. I don't think this ratio developed by Shimizu is an accident. I'd venture a guess that if one were to use a hotter charcoal which probably has a lower ash content, it might be rendered a little bit stronger in a more typical 75:15:10 ratio.

[SeaMonkey]

We did an experiment with Yellow Powder in High School back about 1957.

Although we didn't call it that. We called it Fulminating Powder. Our Chemistry

Teacher was familiar with the substance.

 

Our recipe was somewhat different since we were testing to see if substitutes

would work to create what was then called Fulminating Powder.

 

We heated a mix of Sodium Nitrate, Sodium Bicarbonate and Sulfur in the

usual proportions placed in a metal hubcap then positioned over a flame.

Outdoors of course.

 

We stood some distance away from it but could see that the powder did

melt and bubbled somewhat then just seemed to puddle for what seemed

a long time before it "fulminated." We were quite surprised.

[kleberrios]

A few weeks back I tried making some ball mill black powder with the usual ratios. I used Sulfur found at a garden supply store, Air Float Charcoal, and Technical Grade KNO3. I milled it for about 2 hours or so and then added 5% dextrin and granulated it. It's surprisingly underwhelming. Is Air Float Charcoal no good for making fast black powder? I usually use homemade willow charcoal and it comes out faster burning but ran out for this batch.

 

add 3% water

 

 

https://youtu.be/Fn8zzExiVeg

[Arthur]

The wood from which the charcoal is made is critical, a poor wood will always yield a poor powder. All countries have suitable woods available from local species. In the UK willow or red alder were the preferred choices right back to the Royal Gunpowder Mills at Waltham Abbey (search google find the museum bookstore). RGPM always used powder made in steel cans to keep the heat up and the oxidation down, their book suggests that powder from open pit charcoal was 30% less powerful than from closed can charcoal.

[Arthur]

https://www.royalgunpowdermills.com/rgm-historic-reprint-series

 

Several useful books on the production and proofing of black powder from the days when it was the major/only military propellant.

The ebooks would travel cheaper than the reprints.

[SeaMonkey]

Kleberrios,

 

Your video comparison of Water vs. No Water powders is quite

convincing that water makes a considerable difference!

[Mumbles]

Water make a bigger difference in poor quality BP as shown in Kleberrios' video. Realistically, the biggest difference is probably just that the wet material is slightly granulated and has a lot more paths for the fire to travel. The actual BP isn't any faster. Plus since we never really use open powdered BP, there aren't a lot of applications for that.

[Bourbon]

Water make a bigger difference in poor quality BP as shown in Kleberrios' video. Realistically, the biggest difference is probably just that the wet material is slightly granulated and has a lot more paths for the fire to travel. The actual BP isn't any faster. Plus since we never really use open powdered BP, there aren't a lot of applications for that.

So for those that say, once pressed into a grain a minute amount of moisture "may" convert steam into thrust isn't the case?

 

I've heard this several times now. I understand that it can't make the BP any faster chemically, but is more of a reaction of... Trying to wrap my head around the yays vs nays.

 

Kleberrios also states in a reply to question :

 

Bourbon, on 13 Aug 2020 - 07:18 AM, said:

Do you find the same for compacted, or only loose powder?

 

yes, it compacted is more energic and powerfull.

[kleberrios]

A few weeks back I tried making some ball mill black powder with the usual ratios. I used Sulfur found at a garden supply store, Air Float Charcoal, and Technical Grade KNO3. I milled it for about 2 hours or so and then added 5% dextrin and granulated it. It's surprisingly underwhelming. Is Air Float Charcoal no good for making fast black powder? I usually use homemade willow charcoal and it comes out faster burning but ran out for this batch.

In this video I simply mixture a air float charcoal with Sulphur and Potassium Nitrate ultra thin in the patern mixture 75 15 10. In the right portion I mixture 3% water and in the left portion I don't mixture water. see the diference of the burning. depending of the proposit of use of the black powder you can use it humid. ex. to launch bombs. you must conserv it on a plastic bag to water not evapored

 

https://youtu.be/Fn8zzExiVeg

[Arthur]

Dampness in powder is good, dampness in the ingredients is BAD because charcoal can absorb 20+% of moisture but nitrate and sulphur essentially don't absorb water, so damp ingredients can upset the real proportions of ingredients in the mix.

[kleberrios]

Dampness in powder is good, dampness in the ingredients is BAD because charcoal can absorb 20+% of moisture but nitrate and sulphur essentially don't absorb water, so damp ingredients can upset the real proportions of ingredients in the mix.

[kleberrios]

 

Dampness in powder is good, dampness in the ingredients is BAD because charcoal can absorb 20+% of moisture but nitrate and sulphur essentially don't absorb water, so damp ingredients can upset the real proportions of ingredients in the mix.

 

this method is to powerfull the black powder only. I Don't understand .... KNO3 DON'T absod water? Charcoal and Sulphur don't absord water, Kno3 yes.

[Bourbon]

I think we are loosing some things in translation.

[kleberrios]

Dampness in powder is good, dampness in the ingredients is BAD because charcoal can absorb 20+% of moisture but nitrate and sulphur essentially don't absorb water, so damp ingredients can upset the real proportions of ingredients in the mix.

The water is poured after the composition is mixted not before, so there ins't upset the real proportions of ingredients.

[SharkWhisperer]

Surprisingly, I find myself in agreement with Kleb here. I dry out both my pre-milled KNO₃ and my charcoal (unless freshly retorted) and store with dessicant before weighing for BP. Sulfur? No special handling. Water addition is after milling components together (or screen mixing for BM, etc, when maximal speed isn't a necessity). Just keeps formulations much more uniform, and completely averts clumping issues that often occur in smaller mills. I find it essentially impossible to estimate water absorption by charcoal, and only appreciate its hygroscopicity when weighed before and after an oven drying session--it can absorb a significant fraction of water (not sure about "20+%", but I've recorded 4-5% in some cases where I bothered weighing it. Probably differs from charcoal to charcoal. I use willow. And KNO₃, too, is hygroscopic--I've never weighed before/after oven drying, but it definitely reduces clumping issues when only making smaller batches in smaller mills presumed to be due, at least in part, to unwanted water content.

[rellim]

Does the classics 75:15:10 formula specify dried or freshly prepared charcoal? I once oven dried air float and found it contain around 10 percent moisture. I left it exposed overnight and it regained its original weight by the next morning on a dry winter day.

[SharkWhisperer]

Does the classics 75:15:10 formula specify dried or freshly prepared charcoal? I once oven dried air float and found it contain around 10 percent moisture. I left it exposed overnight and it regained its original weight by the next morning on a dry winter day.

Well, one thing many of us have observed is that charcoal is pretty damned good at absorbing water. Probably varies by wood. Ash content. Starting moisture content (I store mine with dessicant after oven drying, and good for months, but makes it hard to reuse the color-indicating dessicant packs when they're coal black, tsk tsk). But it works for me. So....if you have 10% water in a 75:15:10 mix, you actually have 1.5% water and 13.5% charcoal, not 15%. That may make a difference in burn rate uniformity from batch to batch if sometimes you dry chems & sometimes you don't. Probably no effect on final product if consistently adding that untreated airfloat charcoal, water and all. But your absolute chem ratios might not be exactly what you think they are. Sheesh, though, if Kleb's measuring 20% water content, that is twice the absolute error of the 10% water content versus rellim's observation: that'd mean 100g of 75:15:10 BP would start out with 3% water and only 12% (not anticipated 15%) of actual charcoal. Dialing down your BP's charcoal from 15% to 12% actual would almost certainly impact BP performance, and if some charcoal was dry and some was "damp", good luck on burn rate uniformity across batches. Me? I'll continue oven drying my milled nitrate and any charcoal that's been sitting around before making a fresh BP batch. Consistency is welcome and helpful.

 

Adding water after the fact is a whole different beast.

[Bourbon]

Me? I'll continue oven drying my milled nitrate and any charcoal that's been sitting around before making a fresh BP batch. Consistency is welcome and helpful.

 

 

 

Do you mind sharing your oven drying technique?

 

I read everywhere, oven temps are all over the place. Times I've seen ranging clear up to 10 hours in the oven, or more. I think that would be excessive, but that's my opinion, as I have never done it.

 

[SharkWhisperer]

 

Do you mind sharing your oven drying technique?

 

I read everywhere, oven temps are all over the place. Times I've seen ranging clear up to 10 hours in the oven, or more. I think that would be excessive, but that's my opinion, as I have never done it.

 

Of course.

 

Charcoal, KNO₃, and strontium nitrate all get spread out on a rimmed cookie sheet and are heated near the lowest setting my gas oven will produce 225F/107C for anywhere between an hour and two hours (if I forget). I crack the door as soon as I turn off the oven. To let out any atmospheric or released water as it dries out (natural gas combustion produces its own water, of course). With an electric stove, probably no need. Anyways, door stays cracked for 10-15 minutes while chems cool down to a safe temp to handle without getting burns--usually close when they leave the oven. Then scooped/poured into food-grade polypropylene screw-top jars and one or two Drierite dessicant crystal packets tossed in on top. Strontium nitrate is granular, so is coffee-grinder milled just before heating. Can do about 2 lbs (just less than a kilo) per tray of oxidizers, charcoal is more fluffy so only do a pound or so at a time. Never bother mixing/flipping chems during drying, though some do because they expect better water release. The dessicant packets get returned to the jar after every use, and are heat-recycled in the oven when they fill with water and change color. I'm using smaller 10 gm packets for 32 oz/1 liter jars; a few extra for larger jars. Stored this way, I typically use all the chem in the whole jar and it stays dry (per Drierite indicators). All jars of BP, whether milled dust or granulated/riced. with or without binders, also contain dessicant packets to keep it dry, with water added as needed, if needed, during comp/device construction.

 

This is just the way I do it, and it works for me. Like you said, a thousand pyros are going to do it a thousand different ways. You definitely can go to higher temperatures if you want to, and it'd probably speed things up. KNO₃ doesn't start to decompose until past 400F, if I recall correctly; I'd have to look it up for strontium nitrate. I've seen clear reductions in chem (charcoal) clumping with as little as 30 min heating at low temps, too, but suspect that wasn't enough to drive off all absorbed water. The charcoal is misleading--it can look bone dry and feel like pure dust between your fingers, while containing an appreciable amount of water. Drying is simple and lasts if stored airtight or with dessicant. Routine for me. That said, I don't build a lot of stuff over 4" in diameter, so I go through hobbyist quantities, a few kilos/month, not sacks and barrels like some might. More when I'm making a lot of one thing or pounding a lotta rockets...

Edited August 25, 2020 by SharkWhisperer

[Bourbon]

This is just the way I do it, and it works for me.

 

Thanks! Much appreciated.

 

[Bourbon]

MinamotoKobayashi, milling the charcoal by itself with stainless steel media smashes the walls of all the cells and makes a very dense, non-porous, non-airfloat powder. I don't subscribe the 'forcing stuff into pores' theory. Neighbor J has done some wet milling, and had some safety issues. Maybe he'll chime in about that, I don't remember the details. I make my BP with super-milled charcoal, milled potassium nitrate, and rubbermakers sulfur. I screen twice through 40 mesh, and either screen-granulate, or puck and corn. I have made lift with commercial airfloat as 70-20-10, but 75-20-10 might be better. Airfloat charcoal is NOT very fine (-150 mesh or so), so super-milling it first would be advised. Maybe milling it with the sulfur would make an improvement too.

Justvisiting, I read a comment you made I can't find about your "super milling". You commented saying, super milling the charcoal alone gave fantastic results but "NOT" over milling. Or, something to that nature. I was curious, at what point does it become over-milled? What are the physical characteristics I should be looking for to determine this?

[justvisiting]

Bourbon, I vaguely recall somebody using the term 'over-milling', and I think I responded to it. I don't remember the context though. Anyhow, I coined the term 'super-milling', for no particular reason. My thinking is that when black powder is milled as a complete mixture, it gets 'fluffy', or aerated. I believe this limits the ability of the media to most effectively grind the charcoal component of the mixture. Adding time to the milling cycle helps, but a point of diminishing returns is reached. If the charcoal is milled to a very fine state by itself, a screen-mixed powder can then be made that can perform just as well as the milled powders that most pyros make. I call it super-milling because I mill the charcoal for 6 hours with stainless steel media. The charcoal comes out as a very fine, dense powder which is not easily scattered in the air.

[Bourbon]

Bourbon, I vaguely recall somebody using the term 'over-milling', and I think I responded to it. I don't remember the context though. Anyhow, I coined the term 'super-milling', for no particular reason. My thinking is that when black powder is milled as a complete mixture, it gets 'fluffy', or aerated. I believe this limits the ability of the media to most effectively grind the charcoal component of the mixture. Adding time to the milling cycle helps, but a point of diminishing returns is reached. If the charcoal is milled to a very fine state by itself, a screen-mixed powder can then be made that can perform just as well as the milled powders that most pyros make. I call it super-milling because I mill the charcoal for 6 hours with stainless steel media. The charcoal comes out as a very fine, dense powder which is not easily scattered in the air.

Ah, OK. That makes sense. Thanks!

 

Edit: I found the original post. You are correct. It was in reference to something else someone mentioned.

https://www.amateurpyro.com/forums/topic/13629-air-float-charcoal-black-powder/?p=186714

Edited September 2, 2020 by Bourbon