Advice on Using Phenolic Resin to Granulate BP

[Guest PyroManiac1]

I have just started to experiment with Phenolic resin substituitons. I had a crazy thought today about the substitution of PR to Dextrin in the granulated black powder recipe. Since Phenolic Resin has a very high fuel value I would like to know if this would help me get a faster reaction with my granulated BP.

[Carbon796]

It will likely slow it down noticeably. PR is a better fuel for KP than nitrate.

[Guest PyroManiac1]

It will likely slow it down noticeably. PR is a better fuel for KP than nitrate.

 

Scrap that idea then!

[Boophoenix]

Depending on your ratio of dextrin you may can gain some value from lowering the dextrin amount from the 5 percent often listed. Ned Gorski granulates with just alcohol and no binder. Some have had success with that and others have not.

I wouldn’t completely discount the idea you currently have either. You’ll need to adjust the ratios for the change though. Sounds like it could be an interesting project.

The bigger question is with as few of posts as you have why are you looking for better performance? Are you having a process issue that you may not have nailed down? Should this be the case pucking and Corning may be an options. It will slow the performance slightly, but if you are loosing performance to other issues you’ll be on the upper end of the scale as there are less variables involved in pucking and Corning.

[Arthur]

Professional military BP of past centuries did not need complicated chemicals -they were not available then anyway, but it was still good BP.

 

Go back to basics use a known good ratio of known good ingredients and mill it well.

 

If you need to use a binder use only a little 1% may be too little but 5% is too much, try 2 - 3%, Then of course having lots of liquid in there makes it hard to dry. Make very sure that your powder is dry before use, which can be hard according to the weather where you are.

[Boophoenix]

The reason I mentioned pucking and Corning is touched on by Athur above. Often times beginning we have troubles with moisture levels and drying when making BP. While I’m not a real active builder I have been tinkering with Pyro for a few years now and my location and available time to make BP make it difficult to get it to dry rapidly. Drying fairly rapidly is one big keys to BP performance. Pucking eliminates that as there isn’t enough moisture used to cause a problem. It also provides some pretty good consistency if the supplies don’t change.

 

The three main things in making decent to good BP are charcoal, particle size, and drying time I do believe. Particle size can be cheated a little with a ratio change. It may be possible to do the same with variations in charcoal.

I will add I tinkered one time with a binder that had fuel properties and it didn’t preform very well. I didn’t explore it past one attempt though. So I can’t say if it just made for a crappy BP binder, if it was dried well, or if a ratio change would have helped. I’ve experimented with other things since then and learned a little more and may could narrow down why it did not preform very well now. My first guess would still be the formula was fuel rich with a binder that had fuel properties used in a 75/15/10 mixture with a decent charcoal being used.

[Guest PyroManiac1]

The bigger question is with as few of posts as you have why are you looking for better performance? Are you having a process issue that you may not have nailed down? Should this be the case pucking and Corning may be an options. It will slow the performance slightly, but if you are loosing performance to other issues youll be on the upper end of the scale as there are less variables involved in pucking and Corning.

 

 

The reason I am trying to get better performance is that currently my homemade granulated bp is extremely low quality due to my quality of charcoal and most likely the fact that I don't have a ball mill. I only use a mortar and pestle which doesn't grind large quantities very thoroughly.

 

I will probably have to buy commercial powder until I have access to charcoal other than birch and pine and I have funds to buy a ball mill.

[Boophoenix]

Danny Creagan’s tests have been a reference to possible performances for some time I do believe. I don’t know the details of the testing to say yay or nay, but think he did attempt a quality testing platform. I had a conversation or two on the net with Danny, but really know him either. All that said his results show Birch may have some promise.

 

http://www.creagan.net/fireworks/charcoal_tests.html

 

Dave ( Justvisiting ) has an article link here somewhere abouts on making serviceable BP with commercial airfloat. This was done because a challenge was issued claiming it couldn’t be done. Well, it can with a little effort. I mention this because part of the key I believe is fiddling with the ratios. This will hold true for you as well with the mortar and pestle.

 

Commercial airfloat ranges from something like -60 mesh. Granted the percentages are small of the mesh sizes between -60 and -270. I had some blinding ( screen glogging up ) at +325 and the remainder was the pan. I tried to classify to much material at once which caused some of the blinding. I used a commercial sieve shaker and a random airfloat batch from Harry ( Sky Lighter ) that was from a batch that he had purchased from Service chemical supply.

The particle range you are getting from the mortar and pestle could probably be substantially better. Because of the larger particles your BP is likely oxidizer rich making it preform slower. Lots of other variables in play, but this is a big one from my experiences and Dave’s tests provided all other things are going well.

 

The hottest powder isn’t always the best. There are many people who tone their BP down. Off hand the first groups I can think of are the multibreak cylinder shell guys. I know one of the Allstars from PGI that is a respected builder that does just that for certain. He does mill his BP, but often chokes it back with weaker charcoals. As I recall from a conversation he’s not milling very optimally either, but it’s work great for him for going on 20+ years now it seems.

Aim for serviceable and consistent unless you’re into pushing limits of BP rockets.

[rellim]

I use 2% celluloid table tennis ball dissolved in acetone for bp binder. It is ready to use in an hour. I tried 2% phenolic but it seemed to be too slow.

[MinamotoKobayashi]

I use fast BP with phenolic resin for my biggest rockets, but I enhance it with KP.

Here is my complete tutorial:

 

https://www.amateurpyro.com/forums/topic/13373-my-new-1kg-nozzleless-hybrid-propellant-aluminum-tube-rocket/

 

In a few words I omit the dextrin and add 5% of phenolic resin to the classic 75-15-10 formula.

Then, I add 20 parts of KP every 100 parts of BP+PR.

The mix (pine charcoal, sulfur, KNO3, KCLO4, PR) is soaked into ehtyl alcohol and overmilled for many hours in my ballmill.

To avoid contamination I always use brass balls: they are expensive but they do not lose particles during long milling sessions.

Then I spread a thin layer of the superfine milled paste over a wax paper for a fast drying (to obtain hot BP it is important that the KNO3 do not have the time to recristallize!)

Yes, the PR slow down the burn rate but not too much if I follow the above mentioned procedure.

To compensate the power loss and to enhance a lot the burn speed adding KP is the ideal solution.

I use the phenolic resin because this method completely eliminate the fuel relaxation issues tipical of the traditional BP pressed into an aluminum tube.

Besides this, the pure ethyl alcohol used to slightly wet the mix evaporate fast in my dehydratator and leave the pressed mix hard like a stone.

[Guest PyroManiac1]

As I progress in pyrotechnics I will have to try this sometime. Thank you for sharing!

[Aspirina]

The reason I am trying to get better performance is that currently my homemade granulated bp is extremely low quality due to my quality of charcoal and most likely the fact that I don't have a ball mill. I only use a mortar and pestle which doesn't grind large quantities very thoroughly.

 

I will probably have to buy commercial powder until I have access to charcoal other than birch and pine and I have funds to buy a ball mill.

I have one friend that not have ball mill, he make small shells 2-3" with only 'handworked' bp, for a good perfomance in this way of bp making you must have all the chemicals fine like talc, he use a small electric food mill to grind the chemicals individually then he puts all together in a ceramic mortar and with a lot of patience smash them with the rammer, the best quantity for work is 50g in a large mortar. For granulating (in my opinion) the best performance is only alcohol, I just use cheap 96º and my black powder is really demoniac, I dont like use binders, if you make a decent lift cup to prevent the granules cracking you may dont have any problems... anyway if I must to choose a binder I use red gum and still good results (not like with only alcohol but still nice)

https://www.skylighter.com/blogs/how-to-make-fireworks/red-gum-black-powder

Edited January 9, 2020 by Aspirina

[MinamotoKobayashi]

I tried to granulate the BP omitting the dextrin with only alcohol and the 8 mesh granules are obiouvsly weak and dusty.

Time ago I have made this tutorial:

 

https://www.amateurpyro.com/forums/topic/13068-how-to-make-very-fast-kp/

 

It can be applied also for BP.

 

About the pucking and corning procedure, a lot of time before I have made this tutorial:

 

https://www.amateurpyro.com/forums/topic/12899-how-to-make-hot-bp-indoor-safely-lab-intensive/

 

but as Simoski said, the pressing procedure slow down the burn rate.

Pressing the powder will eliminate most of the water and so eliminate the KNO3 recristallization issue, but the resulting powder is not so fast.

My ballmilling procedure create instead a very hot BP with common pine charcoal, but it can be further improved with faster charcoals.

The ballmill is an indispensable tool to make perfect BP!

Edited January 9, 2020 by MinamotoKobayashi

[Guest PyroManiac1]

I just bought a coffee bean grinder and prepared some unactivated pine charcoal. I was using activated which I heard was the worst for bp. I have high hopes for this batch. I do use 5 grams of Dextrin to 100 grams of black powder. I wet with 50/50 water to rubbing alcohol. Edited January 10, 2020 by PyroManiac1

[a_bab]

I am sold to CMC: very cheap binder, available everywhere.

I wet the meal with the CMC snotty solution (a few percents are enough), and I granulate the dirty dough ball on a grater / window screen.
Once dried (summer is perfect for this), the granules are hard and porous; they don't crumble at all.
Even a peanut sized lump would deflagrate instantly due to the porosity so no loss on speed.

[Guest PyroManiac1]

Sounds like a good binder what does CMC stand for? Sorry I am still learning my chemical abbreviations.

[MinamotoKobayashi]

Uhmmm I suppose that CMC stands for carboxymethyl cellulose.

Very interesting, I never heard that it can be used as binder!

If I will found it I will start some nice experiments.

Thanks a-bab!

Edited January 11, 2020 by MinamotoKobayashi

[SharkWhisperer]

I just bought a coffee bean grinder and prepared some unactivated pine charcoal. I was using activated which I heard was the worst for bp. I have high hopes for this batch. I do use 5 grams of Dextrin to 100 grams of black powder. I wet with 50/50 water to rubbing alcohol.

PyroMan1, I'm not sure where you live, but if in the USA, I'd suggest that you make yourself very very happy and purchase a cheapo Harbor Freight ball mill. With their ubiquitous 20-25% off coupons (can download to your phone from their website), the price is not bad at all and will make a veritable world of difference in BP ingredient integration vs grinder and mortar & pestle. Their double drum 6-lb model is currently advertised online at $57.99, and their single drum 3-lb tumbler is $47.99. You'll see pyro companies selling the exact same Chinese unit for twice the standard price, which is unbelievable to me. I think both units have the same motor, so would suggest going with the dual-jar model. I've made between 125g and 200g batches of BP in each drum, invariably successfully although you may have to let it run a few more hours than a more elaborate/larger mill. Best investment I made early on for producing reproducibly excellent powder. The mods are everywhere online, but it's simple to speed up the rotation from the stock 60 rpm or so to a more efficient 90 rpm by wrapping a 10" tube of slit-open vinyl tubing or such around the drive axle to speed it up. Also, this unit is not a powerful workhorse and you can overload the motor if you're using the appropriate amount of heavy media (e.g., lead) in both jars at the same time. With lighter media this is less of a problem. You'll know if you're too heavy if it stops rolling, lurches, or otherwise runs anything but uniform revolutions.

 

And do yourself a favor and standardize yourself with a good, preferably large® batch of reliable, proven charcoal. Activated charcoal just doesn't fit the bill. For anything pyro except maybe as a diatomaceous earth substitute at 20-mesh to increase a bp prime burn rate/ignition efficiency on stars and such. Seems you're making your own, which is great, particularly given the relative paucity of commercial sources for hot charcoals. What type of pine have you switched to and what's your source? A lot of people, myself included, have had great luck with very inexpensive shredded eastern red cedar pet bedding from Wallyworld or another big-box store. Or red alder shingles that Home Depot sells for perhaps $4 for a bundle that fills a few gallons (worked fantastic--super hot bp--but not really that cost effective). I still have a bunch of ERC and Alder charcoal sitting around getting old--I happened upon a large (for me) supply of weeping willow branches this summer and cannot be more pleased with the consistency and reliability of charcoal that I've made with this tree! Charcoal will absorb water from the atmosphere over time, and that caused me some clumping issues in a smaller ball mill. This was easily eliminated by oven roasting my charcoal at 200F for 30 minutes before milling (my KNO₃, too). The nitrate keeps well in a sealed jar with dessicant packs in it, but airfloat charcoal and dessicant packs don't mesh so well, particularly if you want to heat/reuse the dessicant instead of buying new. But after dehydrating, my airfloat keeps dry for several weeks on its own in sealed jars, perhaps for a month or so in my climate.

 

For rocket fuel I only granulate after wetting/kneading BP dough with 91% isopropyl; dries quickly and speeds up burn rate significantly (I don't press/puck/corn...). For lift powder I add 2% dextrin and wet/granulate with 70% isopropyl (you could use less alcohol but then it takes longer to dry). With only 30% water, I still get sufficient dextrin activation, with sufficient kneading before granulating, that I end up with nearly rock-hard granules and a burn rate very similar to my unbound powder. If it is burns slightly slower because of the binder, I certainly cannot tell this by eye. A small 1-2 g pile of my standard 75% KNO₃ formulation burns in an instant and barely leaves a mark on a sheet of regular white paper. My dumbed down 65% and 60% formulations for core burners burn a little slower but not very much so.

 

Find what works well for your applications, standardize your chems and your methods, and you'll know exactly how it'll behave every time you whip up a new batch, with few (generally unwanted) surprises! Oh, did I mention that a ball mill might be your new best friend? :=}

 

Will be curious to learn how you decide to address your prior BP issues, and what results you achieve!

Edited January 11, 2020 by SharkWhisperer

[Guest PyroManiac1]

Well. After grinding all the chemicals seperately and combining them all by putting them in a container and shaking. Then crushing in a mortar and pestle. The finished product looked promising. I mean it was fine like pyrotechnic powdered sugar. It was so disappointing... It didn't burn any better than the birch activated charcoal. Maybe the burn was a bit cleaner but the reaction speed was the same. I went ahead and granulated it anyways. I guess I will just use this for filler in my shells. I am wondering if the pine I used was really pine, I mean the person I got it from said that it had needles and they guessed it was a pine tree but now I am not so sure. Honestly, by the time I order the ball mill, and order some expensive Willow or Balsa wood off of eBay it will cost over $150. For $100 I can order 4 pounds of 1fg black powder (shipping fees included). I really don't think it is worth it at this time to struggle making black powder when 4 pounds will work as lift for over 320 2 inch shells. Eventually, I will try another go at making black powder when I get myself a ball mill and some better wood.

[SharkWhisperer]

PyroMan--Shaking in a container usually won't give you very good mixing--the components have different densities and the lighter charcoal tends to float atop instead of integrating. Wet granulating helps integration but if you're wetting a heterogenous mixture to begin with, you're going to have continuation of the same problems (though it might speed things up slightly). Suggest 2-3 runs through a 20-40 mesh screen if you aren't ball milling. Cannonfuse.com has small ones (maybe 6") for $6 and larger ones that fit atop 5-gallon buckets for I think around double that cost.

 

Seems to me that your charcoal is not your friend. And buying willow/balsa off of ebay is not sustainable, except for the smallest of projects. Making charcoal is easy, and getting a decent stick of true pine is also as easy as walking into a local Home Depot and plunking down $2 for their cheapest 2x4. A lot of trees have needles--that doesn't make them pine, or the correct pine for pyro uses. Yes, ordering commercial BP is one avenue to take, but it would probably be much more rewarding if you fixed your current problem by yourself (and you'd learn quite a bit, too, perhaps), instead of taking that route. And 1fg sounds a little large grain for lifting 2" shells. I'd rethink powder sizing if you go this route. There are charts with typically recommended sizes available everywhere if you look.

 

I can't guess about the quality of your KNO₃ or your S, but it's pretty clear that your charcoal probably is causing major issues. I'm happy to send you a little homemade willow charcoal if you want to test your technique with a proven charcoal. Unfortunately, I don't have quantities sufficient to market, but always have enough to share. It might change your perspective. If you want to try it out, then PM me and we'll sort something out!

[Guest PyroManiac1]

I regranulated my mix several times and I am actually surprised to say it burns a bit hotter now. It still isn't good enough to lift one of my shells but it is good for a burst charge.

 

I was using this conversion chart https://www.skylighter.com/blogs/fireworks-information/black-powder-for-fireworks

Which says that 4fa (1fg) is most commonly used as lift powder. What would you suggest?

I am hoping to lift 2" and 3" shells mostly (maybe 4 or 5" sometime later on).

 

If I am gonna trouble myself to make black powder, I am going to do it right. Since Willow is extremely expensive.

https://www.ebay.com/i/112131625858?rt=nc&_trkparms=aid%3D1110001%26algo%3DSPLICE.SIM%26ao%3D1%26asc%3D40740%26meid%3D14d66897d4d44b3d9c3e345bb3fc5a6b%26pid%3D100694%26rk%3D1%26rkt%3D29%26sd%3D112131599429%26itm%3D112131625858%26pmt%3D0%26noa%3D1%26pg%3D2386202

 

I would probably go with balsa. Which can be picked up from any hobby store affordably.

[SharkWhisperer]

Sometimes regranulation can improve things. That said, you want to standardize your methods, and streamline them, to achieve uniform, reliable, and sufficient results. So I wouldn't be considering regranulation a viable "necessary" protocol step.

 

Most folks I know use 2Fg for shells up to 4", some to 5"; above that, it's too brisant and risks damaging your shells or blowing tubes. At 5" and above, most (that I know) use 1Fg which is almost cannon sized. Here's a link to a decent table of starting charges of 2Fg for various shell sizes: http://www.wichitabuggywhip.com/fireworks/liftCharges2fg.html

 

Another thing about the commercial BP is that it's great for lift, but has other additives that may limit its use in other applications because of interactions with other chemicals. Plus, it's hardened, making it difficult to break down into smaller granules or powder (ball mill, ahem) for different uses (e.g., rocket fuels, stars, comets, fountains...). My BP from cedar, alder, and willow all burn faster than Goex at the same (approximate) grain sizes. It's easy to slow down a hot mix, but impossible to speed up a slow BP without adding non-BP chems (e.g. Benzolift). If you were restricted to using commercial, and you are not, then you'd probably want a variety of sizes such as 1Fg, 2Fg, 4Fg, and Meal D for powder work and making blackmatch. That can get expensive, especially if you switch interests and use more of one type than another, which then sits around on a shelf. Apart from the fact that, excluding labor time (which I enjoy) and alcohol (which is an unnecessary preference), it costs me, as a hobbyist buying chems in smaller 1-10 pound lots, approximately $4/pound of super hot BP, slightly cheaper for slowed down rocket fuel. A pound of Goex is probably $20-$30, plus hazmat if you don't have a local supplier (can be hard to locate in many places).

 

That ebay Willow is ridiculously priced, and one type of willow or another grows essentially all over the lower 48 at least. Look for water, and you'll often find willow; there are many varieties beyond the familiar weeping willows (which is what I have and makes BP that burns damn near like flash). That slab on ebay is for artistry work, not pyro work.

 

Balsa? Whoa, should burn hot & fast, but three issues: 1) it's super expensive, particularly to retort down to charcoal, 2) It's super low-density, which is good but bad for making charcoal because you can only cook a few ounces at a time unless you build a rather large oven; and 3) any charcoal would be super low-density and a pain in the ass to work with in any quantities--it would probably end up being the limiting factor in how much volume you could make at one time, whether in a mortar or in a ball mill. You will go broke and perhaps a little crazy if you think you're going to make cost-effective charcoal from hobby store balsa...fast BP oh yes, but just not worth it unless you've got access to a lot of wood for cheap (scrap from a mill?), and a way to cook a lot of volume at one time. Figure you'll lose at least 70-80% of dried wood weight after converting to charcoal.

 

Why not eastern red cedar? For a few bucks you get a huge bag. At any Wallyworld (cheaper) or pet store. The label will say clearly the wood type, and ERC has a very strong pleasant cedar smell with reddish streaks/chips, so there's no confusion. And it makes very hot BP! It's already shredded, so retorting to charcoal in a gallon paint can (or larger) is more uniform than with different sized sticks, and a little faster. Simplest thing in the world. Stuff an empty clean gallon paint can. Pop a hole or two in the lid with a nail, and toss it into a campfire, or nestle it into a bed of charcoal out back on the Weber!!! Reposition it occasionally to evenly heat, and when the smoke from the holes slows to almost nothing just take it off and let it cool; maybe cover the holes with a wet piece of cloth or something if you're paranoid about O₂ entry while cooling that could cause combustion or ash formation. Presto--super hot charcoal. Simples! And cost effective (moreso if you cook 5-6 gallons at a time instead of 1 gallon, or use a TLUD; I retort 6-gallon batches, which suits me fine. One batch is enough charcoal to make around 10 pounds of BP.

 

Let me revise my offer, because the idea of locating willow, alder, cedar, or even proven pine (have never used the last) somehow seems problematic for you. I am happy to gift to you some super-hot airfloat ERC charcoal, made from Walmart pet bedding and easily reproducible on your end. It makes BP that'll blow your doors off compared to your current stuff, and, if desired, you have the ability to do so yourself, cost-effectively, and in quantity. That said, even with ERC, my milled/granulate is still probably twice as fast burning as my talc-fine nonmilled but screened & granulated powder... The milling makes an amazingly huge difference. And although I'm sure it's decent exercise, the constant mortar & pestle action risks you developing pyro carpal tunnel syndrome and other unfortunalities.

[Guest PyroManiac1]

So Eastern Red Ceder seems like the most economical option. I really must thank you for your offer but I would like to do this myself 😁! How would you compare the ERC black powder to the Willow? Will I be able to use the usual 10% weight of the shell for lift? Is the ERC powder equivalent to commercial?

[a_bab]

@MinamotoKobayashi: yes, with CMC I meant carboxymethyl cellulose, often used as a wallpaper glue. If you like mcDonalds food then chances are you drank it (their "shakes" make use of it as a thickener agent. Yuck !).

It's somewhat similar to wood (PVA) glue in the sense of loosing lots of volume on drying making it useless for star binding because the stars will be rendered very porous (at least on hand pressing with a regular star pump, never tried with a plate). Plus it brings yellow in flame.

But for BP is ideal: it leaves lots of porosity, hard granules, its cheap as chips and easily available, and you end up with 1% or less in the compo meaning it won't balance out the BP too much, unlike other binders that would "steal" oxygen from the nitrate, slowing down the BP.

I start by dissolving in cold water some CMC (usually a tea spoon in 500 ml of water), enough to turn the water into a thin jelly like consistency. It looks quite disgusting in fact, like someone collected snots for a month, with some small CMC particles that never dissolve.
I never weighted how much CMC but I think its just a few grams: CMC is very fluffy but it can also come in granules.
then add this snotty mess to meal in small portions while kneading it. This will cause a cooling down reaction due to some of the KN dissolving in the water. The CMC solution will be absorbed into the meal eventually; the goal is to get a thick putty, similar to what you'd do for cut stars (maybe a bit wetter). Once grated and dried it gives a very hot BP.

I initially pressed pucks and cornered them, with 70% alcohol and no binder of any sorts - this also gives very hard granules but the corning step is nerve wrecking and takes lots of elbow grease so I dropped it.

In practice the CMC bound BP is as fast if not faster than the pressed BP.

[SharkWhisperer]

So Eastern Red Ceder seems like the most economical option. I really must thank you for your offer but I would like to do this myself ! How would you compare the ERC black powder to the Willow? Will I be able to use the usual 10% weight of the shell for lift? Is the ERC powder equivalent to commercial?

With my preparations, BP with ERC vs Willow charcoals (or red alder) are not perceptibly different in burn speed--i.e., they're both consistently great. I haven't performed any of the typical tennis ball time-in-flight from 3" mortars or timed the burn rate of a long pile of powder, but both burn quick enough not to char standard white writing paper when ignited in a few gram pile. And they both make badass rocket fuel as well as lift... I rate my powder burn speed using a more subjective 1-10 rating, with 10 being the fastest i've ever seen and loosely approaching the "poof factor" of mediocre flash. My 75% KNO₃ standard granulated formulation consistently rates an "8.5-9", and my 60% KNO₃ for nozzled core burners typically rates a "7-7.5" and will leave small char holes on paper. Anything slower just sets paper alight. By comparison, I rate Goex 4f as about an "8" in subjective burn rate, unconfined. If memory is correct, I'd likely have rated my ancient mortar & pestle batches using conventional hardwood airfloat somewhere around a subjective "5" in burn speed, at best--it was really horrible but very much fun when you didn't know any better.

 

Good luck. I appreciate that it's most rewarding when you do things start-to-finish and troubleshoot by yourself. Offer remains open, nonetheless, if for nothing else than to have something to compare to your improved formulations.

 

If you go the ERC route, it's hard to screw up. There's plenty of advise and videos. Only trick is not to overcook (or aerate while still hot) to ash or to undercook too much. If you start out with a gallon paint can. Make sure the lid's pounded down tight. Don't need a ton of holes--I used to use 2 1/8" nail holes. If you flip it upside down (sometimes sideways) then the emitted gasses will burn like a tiny jet engine and you can capture that heat to continue. When emitted gasses can't be lit with a camp lighter or torch, you're done. Cover your holes (I do; probably not necessary) and let it cool down. Paint cans have a limited lifespan--I only used one before upsizing, and it lasted either 4 or 5 cooks before it pretty much fell apart and hit the recycling bin. Currently use a 6-gallon Behren galvanized steel pail (on Amazon, and at Home Depot, but was surprisingly cheaper from a nearby Ace hardware), but it is definitely "leakier" than the lid on a gallon paint can; nonetheless, so far have gotten several large batches of excellent coal that will last me awhile. I cover/wrap it with a wet towel after cooking to seal the leaks and prevent ash formation, & no problems so far. About as low tech and hassle-free as it gets. Plus, it's kinda relaxing to turn it with a stick like a sausage at the firepit!