Issues making black powder/gunpowder

[Craigo]

Hi, I am having an issue when igniting my homemade black powder and I don't know what to do further, I have searched for issues similar to mine but haven't found what I need to actually do. I only need this to get an A in chemistry so I don't want to spend too much money. I have followed a recipe I found online and thought everything was going well until I tried lightning on fire a paper under the powder and nothing happened, the paper burnt under it without igniting the powder itself. Then I tried to set fire to the powder directly with a lighter (I know it's dangerous and looking back it was really stupid) and still nothing. I used the 75% Potassium Nitrate, 15% Charcoal, 10% Sulfur mixture. For sulfur I found some sulfur batons that are supposed to be used for cleaning wine barrels, for charcoal I used ones from a grilling bag and for the saltpeter (Potassium Nitrate) I got a bag of dry fertilizer. Using a mortar and pestle I made fine powder of each of the ingredients and stored them separately in glass jars, sealed. Went to the countryside where, using the mortar and pestle I mixed them until I got a gray powder. I am not sure what I did wrong, maybe I cheaped out on the saltpeter because the fertilizer one is brown not white as it should be, but I still don't want to spend too much on this project. Any suggestions?

[Zumber]

At first sight it seems chemicals problem.

At least powder should be burned out.

[MadMat]

You definitely have a problem with your chemicals. It might be more than you need, but you can buy a pound of both potassium nitrate ($4.94/lb) and one pound of sulfur ($3.29/lb) + shipping from Dudadiesel.com. Don't expect anything good from using barbecue charcoal. First off, charcoal briquettes are made from hardwood, which makes notoriously bad black powder. Additionally, charcoal briquettes have a binder, such as bentonite clay,  added for them to hold their shape. You would be better off finding a small metal paint can with a friction top (one that you have to tap on). clean it out and you can put in pieces split off a 2x4 (make sure its not green treated wood!) or even popsickle sticks (available in the hobby department at your local Walmart for fairly cheap). Drill a small hole !/4" or smaller in the top and put it on a grill or a campstove (outside) and cook this until it stops producing gas out of the hole. You will notice that the gasses coming out of the hole are flammable! Cover the hole with a coin until it cools (because at that temperature your new charcoal will actually ignite if it contacts the oxygen in the air). Not only will you be able to make halfway decent black powder, but you will also, as an added chemistry bonus, learn about the basics of destructive distillation (you can google this for more information) when making the charcoal.

Edited April 24 by MadMat

[MadMat]

Grind all your chemicals separately in the mortar as fine as you can get them and then sift them together through a screen or kitchen strainer. Gently, run this powder through the screen a number of times (5 minimum). You then should have black powder that will not only light, but should burn fairly fast. This black powder probably won't be good enough to make any firecrackers or an explosion (still though, don't relax your safety precautions!), but it should be fast enough for a chemistry demonstration. FYI, if you follow this, what you have made is not actually black powder, but what is known to firework makers as "polverone". To be true black powder, it would have to be milled in a ball mill and granulated or corned.

Edited April 24 by MadMat

[Craigo]

I see, I will try and do as you have told me with what I have available, I'm not from the US so I will have to adapt and I can't really order this stuff online. As far as I understand the powder isn't igniting because of poor quality charcoal, right? If I make my own charcoal from soft wood will it light up?

[MadMat]

When you mentioned that the fertilizer was brown instead of white, I was very suspect of that as well. I'm not sure if the country you live in rates fertilizer by the NPK system. IT is a series of three numbers; the first being for N or nitrogen, the second being for the P or phosphorus and the last one is potassium for the K. You may notice these letters are all taken straight from the periodic table of elements. A fertilizer with a lot of potassium nitrate will have a very high first number and a low last number. The middle number should be as close to zero as possible. Something like 60-5-20 (don't look for exactly these numbers but this was just to give you an idea) would probably be high in potassium nitrate. Unfortunately, some fertilizers utilize urea or even ammonium nitrate instead on potassium nitrate for nitrogen, so you will have to actually look at the ingredients listing. If there is no listed ingredients see if you can't obtain a MSDS (material safety data sheet). These usually contain a chemical breakdown list.  Another possibility is if there is tree stump remover available in your country. Garden supply or hardware stores usually carry this and if you get the right brand it is almost all pure potassium nitrate. I have used this in the past and it was pure enough to work quite well.

 

[Arthur]

There are whole webpages devoted to BP, and whole pages devoted to charcoal for powder. Pure potassium nitrate is hard to find, but fertiliser grade pot nitrate is easier, it should be in a white powder or white crystal form. 

[Craigo]

When I bought the fertilizer I looked at the back and grabbed the first bag that had Potassium in it so I guess that was my first mistake. The back of the bag that I bought uses the NPK thingy and it reads:

Nitrogen by %: 6.0

Total Phosphor as P2O5: 2,0

Potassium as K20 : 5,0

The fertilizer is supposed to be used for a plant called Rhododendron if that's any help. But either way I will check the hardware store for stump remover, thank you!

[Craigo]

Forgot to ask, but I think my sulfur is good right? It has the color (and the smell) of what I've seen in videos so I hope I got at least one of the ingredients right.

[Zumber]

2 hours ago, Craigo said:

Forgot to ask, but I think my sulfur is good right? It has the color (and the smell) of what I've seen in videos so I hope I got at least one of the ingredients right.

there are only three ingredients.

Change one ingredient at a time and test formula.

You will easily find out what chemical is not right.

[Richtee]

I have posted on charcoal before. Newsprint. You don’t NEED exotic woods. I have made some of my best BP using packing paper/newsprint for charcoal. Use the method MadMat suggested. Pack it in tight with something and cook it. It’s so easy to airfloat it too. Meaning less grinding/mill time, etc.

[Craigo]

I have been to the hardware store and have searched online and there is no stump remover anywhere, not for sale to the public anyway. I looked for better fertilizers in the gardening section and still nothing good, nothing even comes close to MadMat's 60-5-20. Some of the values I have found following the N-P-K system:
11% - 0.2% - 0.5%
38% - 6% - 6%
19% - 6% - 20%
7.5% - 0.4% - 2.5%
I don't want to buy every single bag and test it individually as it's very expensive and incredibly time consuming. Can any of these 4 be used as a saltpeter substitute?
Also, for the charcoal I will go out tomorrow and buy a set of popsicle sticks to make my own charcoal, unless I find some soft wood in my backyard. Thank you for your help so far!!

[Craigo]

Searched far and wide across the internet and found a big ass 5lb bag of fertilizer claiming to be potassium nitrate, ranging from 13.5% to 45.5%, not sure how good that is. It contains:
Total Nitrogen (N): 13.5%
Nitric Acid: 13.7%
Potassium Oxide: 45.5%
I genuinely don't know what I'm doing, sorry.

[DavidF]

In my country (Canada), potassium nitrate was sold in small bottles of about 100 grams in drugstores. Maybe it still is. Also, potassium nitrate is commonly sold in hydroponic supply stores. I don't know why you would buy popsicle sticks to make charcoal when a much cheaper and easier source (newspaper) was already suggested, which will work WAY better in your situation. 

[Richtee]

3 hours ago, Craigo said:

Searched far and wide across the internet and found a big ass 5lb bag of fertilizer claiming to be potassium nitrate, ranging from 13.5% to 45.5%, not sure how good that is. It contains:
Total Nitrogen (N): 13.5%
Nitric Acid: 13.7%
Potassium Oxide: 45.5%
I genuinely don't know what I'm doing, sorry.

Potassium Oxide? WTH... that label is BS. Guess I don’t know where yer located, but I’d send ya a pound for shipping cost. Hell..I’ll toss in the sulfur too.

And try the newspaper. 

[Craigo]

Very kind of you to offer but I live in Romania, the shipping cost would probably be more expensive than the saltpeter itself. I will keep looking and asking around for at least 10 grams of this stuff. I will try the newspaper instead of the popsicles, all I need is to find an old paint can. So none of the N-P-K combos I found above work, right?

[Arthur]

If this is for a school project, perhaps the school can find potassium nitrate from a school laboratory supplier and let you have the required quantity.

[CountZero]

Npk around 13 0 46 is what you want. 

If in doubt try to look at the safety data sheet. 

Edited April 26 by CountZero

[Craigo]

It is for a school project, I have asked my teacher to give me some clues as to what I've done wrong (after I failed the first time) and she told me to figure it out, so no help there. I don't know what a safety data sheet is, I searched it up and it doesn't really help me

[Arthur]

Your teacher probably means that you should check everything that you have and have done -this is part of the learning process, often more is learned from a failed experiment than from a perfect success.

[CountZero]

22 hours ago, Craigo said:

Searched far and wide across the internet and found a big ass 5lb bag of fertilizer claiming to be potassium nitrate, ranging from 13.5% to 45.5%, not sure how good that is. It contains:
Total Nitrogen (N): 13.5%
Nitric Acid: 13.7%
Potassium Oxide: 45.5%
I genuinely don't know what I'm doing, sorry.

I think this is what you want.... 

[Craigo]

I spoke to a family member that works in the industry and told me he could get some potassium nitrate either later today or after the weekend, so I got that covered. I'm still looking for a metal can to make charcoal out of newspaper though

[Craigo]

I got the saltpeter, it's in tiny tiny balls, white as snow, so I imagine this is the good stuff. Only charcoal left I guess, thanks to everyone who helped me!

[Richtee]

On 4/26/2024 at 12:48 PM, Craigo said:

I got the saltpeter, it's in tiny tiny balls, white as snow, so I imagine this is the good stuff. Only charcoal left I guess, thanks to everyone who helped me!

You’ll need to grind that KNO3 fine. Well..everything  actually. If you get a food can, use it. Cover the top tightly with 3 layers of heavy gauge AL foil and roast that sucker. I use a fine thread drywall screw and “drill” by hand into the foil. When the smoke coming out stops, I remove from heat and “thread” the screw back in and wait for it to cool. POOF...charcoal.

Edited April 27 by Richtee

[Craigo]

Got an old coffee can, cleaned it out and if I can, I will try tomorrow to "bake" my charcoal. Question, if the lid doesn't fit very tight, should I tape it? It inserts fine but I wasn't sure it was really sealed, so I put some water in, shook the can a bit and found out it leaks. Not a whole lot but I think the gas will get out through there..