Advice on Using Phenolic Resin to Granulate BP

[Guest PyroManiac1]

As for a ball mill. Is there a specific brand of rock tumbler that you would recommend? I have heard that to make the hottest bp you need to mill for around 12 hours. Is there a brand you know of that can run that long without burning out? Many tumblers have bad reviews as many burn out or their belts break. Edited January 15, 2020 by PyroManiac1

[SharkWhisperer]

As for a ball mill. Is there a specific brand of rock tumbler that you would recommend? I have heard that to make the hottest bp you need to mill for around 12 hours. Is there a brand you know of that can run that long without burning out? Many tumblers have bad reviews as many burn out or their belts break.

Before I made my own mill, I used the good ol' Chinese Harbor Freight 2-barrel (6-pound) model, for years, and never broke a belt. They're cheap as can be (mine was around $50 with tax), especially with the ubiquitous 20% off any single item coupons that are available online, and come with 4 or 5 extra belts (which others have improvised from vacuum cleaner belts in a pinch). If there's a local store nearby, they accept returns/exchanges for any reason at all within I think 90 days; I don't know the policy if you buy online and have to have it shipped to you, but easy to find out. Read the reviews at harborfreight.com and here--some people have gotten a dud unit, but many pyros, myself included, started their BP milliing careers with them. They're cheap as dirt unless you go the homemade mill route, and there's many tutorials available all over the web for making a DIY mill. If a HF rock polishing unit breaks (within 90 days), you just keep returning them for a new one until you get a decent one (perhaps retain the extra belts just in case--they're overpriced if you need to buy them for some reason).

 

They're made for polishing rocks, which means running day & night for weeks sometimes! I would put a drop of oil on the ends of the rotating rods when I'd remember (my negligence probably meant every 30-40 hours of runtime on average) and sped up rotation to improve milling by wrapping the drive shaft with a 50-cent piece of vinyl tubing to increase its diameter (details available if you look or ask). Never had one fail or overheat. It is easy, however, to overload them with too much weight so they lug or stall, potentially damaging the motor, but that's pretty easy to sort out. It spins easily or it doesn't. Mine was/has been trouble-free. With super dry chems, my BP is pretty quick dust with just a few hours milling, top notch by 6-8 hours of milling, and hits a point of diminishing returns and maxes out after a 10-16 hr milling with no real additional benefit. I tended to get clumping issues if using KNO₃ or charcoal that wasn't bone-dry, but that's a simple fix with the kitchen oven.

 

If I use 60 .50 caliber musket balls (fills one jar a little less than the optimal 50%--maybe to the 40% level), I can only run one jar at a time (max 200 grams BP components; a little faster with 150 g loads if you're in some kind of hurry) or it'll stall. I never weighed my filled jars, so don't know if their "6-pound" description is so accurate. Anyways, this will make the old-timers cringe, but I could and did run both jars simultaneously using 50% volume of dollar-store glass marbles as mill media for a long time and made great BP. I was a convert after my very first batch vs screening or bashing with a pestle. Glass is lighter, so milling with lead or stainless balls is more efficient, but it worked just fine. Some have indicated that glass marbles might: 1) spark, potentially causing a catastrophe (your mill is in a safe place, right?), especially if the glass contains additives (metal salts for colors?), 2) chip glass fragments into your mix, or 3) be inefficient because they're lighter than lead. Though I by decorum and extreme caution could never recommend glass milling media, I never had any issues apart from it taking a little longer to mill fast BP vs using lead because glass is less dense. Maybe I just got lucky (perhaps a hundred times)? But I never had any identifiable safety issues. Plus, I could run two full-load jars overnight instead of just one with lead. Read the incident reports of ball mill explosions, though, and use good judgement in your milling practices. As always, safety is paramount and the responsibility for safety is on your shoulders.

 

But it'll definitely make you smile when your first milled BP batch burns like lightning and is actually useful for a diversity of pyro applications!! Lift, rocket fuel, blackmatch, gerbs, shells...all need reliably decent BP. Have fun !!

[MinamotoKobayashi]

I tried the chinese one but the motor was undersized for my uses, so I switched to Lortone Rock Thumbler from Pyrogarage.

It costs more but the quality is fantastic!

Both the motors tend to overheat especially if You load heavy medias, so usually I open the chassis and put an external cooling fan.

Edited January 15, 2020 by MinamotoKobayashi

[SharkWhisperer]

Lortone had a decent reputation for their smaller hobby mills. I'm sure you could find them for a decent price in the USA, Ebay link shows several models starting around $100 for a single-barrel 3-pounder: https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1311.R1.TR11.TRC1.A0.H1.XLortone+.TRS0&_nkw=lortone+rock+tumbler&_sacat=0 . The single-barrel base-model Lortones are about $95 on Amazon, with free shipping: https://www.amazon.com/s?k=lortone+rock+tumbler&crid=2QCIGCIOG1V83&sprefix=lortone+ro%2Caps%2C200&ref=nb_sb_ss_i_1_10 . Amazon also sells the same Chicago Electric models as Harbor freight ($57 for 1-barrel, $67 for 2-barrel, both with free shipping; this is more expensive than HF in-store, especially with a 20% off coupon). There are some other models available on Amazon that probably come from the same factories. The ratings for the Lortones are a little higher than the HF/CE models, but all of the Lortone 1-star reviews are for the same reasons as crummy HF reviews--motors seizing and belts breaking...

 

For pyros in Europe, Pyrogarage might be a viable source, but ordering to North America doesn't seem common (they're in Poland), and their cheapest model shown on their website starts at PZN690, which is US $179 before shipping, for the basic Lortone single-barrel 3 pounder.

 

For those in the US (and Canada?), if I had a local store, I'd probably begin with another HF 2-barrel unit if I were to do it again. Easy returns through 3 months with no reason necessary. If I had to have it mailed to me at my expense, or if I had to pay to ship a defective unit back to HF, that might cut into cost savings and have me looking locally or for another model. Else you always have Amazon and can contribute a little to Jeff Bezo's pathetically deficient piggy bank account (sarcasm).

 

As always, shop around. Many pyros eventually upgrade to larger-capacity models. I could only spin 200g BP max in a HF barrel, but that was enough volume for me for awhile, and made smoking hot BP. As your rockets and shells get bigger and more numerous, and they will if you advance in the hobby, you're going to need proportionately larger BP quantities.

 

But making BP without a mill, any mill, is an exercise in futility. In my eyes, screen-mix is for gerbs, stars/comets, and wimpy core-burners and the CIA method is only semi-consistent and seems to be a laborious pain in the ass. You'll want a hot mix for rockets, lift, and burst that screen mixing, again only in my opinion, suffers to provide.

Edited January 23, 2020 by SharkWhisperer

[Guest PyroManiac1]

Yeah I think I will go with the Chicago Electric single barrel when I get to harbor freight.

[SharkWhisperer]

Hey there, Amigo,

 

I don't know where you are in the US, but HF prices are the same all over, it seems. Anyways, their online price 5 minutes ago for a single-drum was $48 and for a double-drum was $58: https://www.harborfreight.com/search?q=rock%20tumbler

 

Knock off 20% coupon and add taxes, yada yada yada...IF you can't find the coupons, then sign up online at their site and they'll email (or snailmail) them to you. Around $50 for the double. Get that instead of the single. Here's why. Not 100% positive, but about 90% positive that the single and double barrel units have the same motor. So, for $8 more (after coupon), you get "twice" the capacity, or at least an extra drum (inside is rubber lined, which will eventually wear out--though mine lasted at least 200 hours without worrisome wear). That way you can run two drums with lighter media (stainless perhaps) or one loaded for max efficiency with lead media, and have a spare drum. The spare drums are on Amazon but cost more than $10, though you'll have to research yourself because I did not commit that price search to memory.

 

You are gonna LOVE your improved BP with milling, no matter which charcoal you are using!!! But make yourself some decent charcoal. Here's how it works...3 levels: 1) My mortar n pestle ground BP with crappy charcoal=wow, it burns, but won't do much else; 2) Rock-tumbled BP=WOW I never knew my BP could be so badass (but my charcoal sucks so it isn't good for much more than fountains n slow stars that I can't even launch cuz my lift sucks); to 3) WTF?!?!? Rock-tumbled BP with my homemade charcoal DOES IT ALL !!!!! Whoo hoo, you'll barely contain yourself with unbridled glee. And self-respect for your accomplishment. And your BP will be applicable for any and every pyro application that uses BP (uh, most). You will experience a definitive measure of new happiness. Congratulations! You can make decent BP. That is the first badge of a good pyro. After that, everything else is "cake" and "flowerpots" (get the joke? yeah, yeah, I know... super lame)!

 

But you will have afforded yourself new options. Many. Have a blast!!!!

Edited January 24, 2020 by SharkWhisperer

[Guest PyroManiac1]

Ahh ok! Thank you for your response! I was planning on using some 3/8" stainless steel bearings for media? If the single drum and the double drum have the same motor wouldn't you only be able to use one of the drums at a time anyways? Or would I get to use both because of the stainless media I am using? How much stainless media by weight should I add so I can run two 200g batches at a time without burning out the motor?

[SharkWhisperer]

Yo PyroManio!!!

 

I started making BP with a HF rock polisher. I started using an unweighed jar of dollar-store glass marbles. Maybe 5/8" (sorry EuroFolk, don't feel like doing the metric conversions; seems to me to be about 15 mm though...). Worked great. Lead .50 cal musket shot is what I used next (not hardened with antimony, although that is an option). When I started, glass was not a widespread caution in the BP-making world. In my opinion, it still is not worthy of serious caution/paranoia, and I would happily mil BP with marbles (colored too, with metallic salts no doubt) without serious concern. That's my risk level, not necessarily yours.

 

3/8" is fantastic if that's what you've got in hand. Stainless is proven, though you will find no shortage of arguments about which stainless (i.e. carbon content) is best. Meh. Fill your jar halfway and then add powder mix to fill the gaps and cover slightly. The "optimized" specs are available all over, but half milling media, 1/4 jar of total powders (in theory fills to half after filling gaps between spherical mill media, is usual. I've overloaded HF mills. With marbles and lead. You just need to mill an hour or two longer. No big deal. My range per HF bottle was 100-200 gram batches. Never a "failed" batch. Biggest issue with that unit was when I didn't use completely dry chems and the BP would clump (sometimes really hard) after a few hours, or longer, apparently moisture-dependent (I stick my nitrate and coal in the oven for 30 minutes if I haven't milled in a few weeks--makes life much more pleasant and cooperative).

 

Major Bonus: Charcoal is light. You can always mill both jars, even overloaded, with charcoal and whatever media you have at hand. Without overloading the motor. I always pre-mill my charcoal, before it's to be milled into BP over 8 hours in the complete mix (the old dudes with multi-gallon mills are laughing at us now! 8 hours?!? Ridiculous!!!). You can also be lazy and just toss charcoal chunks with the other 2 and grind away... You will feel slowed down eventually by a two-small-jar hobbyist mill--I used mine for years and still think fondly of it. A 1-barrel unit, in hindsight, would have measurably hobbled my progress by a significant extent. It's $8-10 difference only. And you can always return it, without a reason necessary.

 

Looking forward to your first reports of your milled BP!!!

Edited January 25, 2020 by SharkWhisperer

[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.

Like Aspirina, I granulate BP with alcohol only, for use as rocket fuel and burst, and other items where granule toughness isn't a huge concern. But Minamoto is correct insofar as no-binder alcohol (or water) granulated 8-mesh (or any size actually) BP granules are not structurally tough, but they burn fast. For lift I add 2% dextrin, generally screened in after milling, unless I remember to mill it together. 1% dextrin just doesn't give sufficient hardness, and any more than 2% I find unnecessary to maintain granule integrity. 5% noticeably slows my powder burn rate at any granule size.

 

Here, Walmart sells isopropyl as either 50%, 70% (what is most common elsewhere), and 91% concentrations. For no-dextrin BP, I want granules, minimal KNO₃ solubilization, and quick drying, so I use 91%. You can get it good n wet without worrying about the 9% water causing crystalization issues, and it dries pretty quickly. With Dextrin, though many add 25% isopropyl or so to break surface tension, I just use straight 70% isopropyl and don't worry about overwetting. Make a nice putty and work it like a loaf of bread for 5-8 minutes or so, so that the 30% water can meet dextrin and do its thing; still there's 70% alcohol that evaporates pretty quickly, again avoiding crystalization issues or excessive drying time. A silica packet in the storage drum will take care of any remnant moisture overnight, if the BP is put away before complete drying. I'm probably using alcohol unnecessarily, but i like the rapid drying, volumes used are pretty limited, so the cost is not outrageous ($2.50/liter or so; rising slightly with increasing concentration). 2% dextrin doesn't inordinately slow burn time and the granules are pretty tough if you give the dex time to work and massage your wet BP ball adequately before granulating.

 

But to each their own. No reason not to use red gum or phenolic if it's doing the job for you, apart from the minimally increased cost vs dextrin. With my method, I'm using sufficient alcohol for both of these binders to be used, and sufficient water for dextrin to function. Comes down to personal preference.

Edited January 24, 2020 by SharkWhisperer

[Guest PyroManiac1]

Very helpful! As always! So if I use Eastern Red Ceder shavings the charcoal chunks won't be very large. So if I add the charcoal as is with the other components do I need to mill for any extra time? Maybe 9 hours instead of 8 to make sure that charcoal gets crushed?

[dlking59]

I got the two jar mill from HF. For the $10 difference I get the 2 jars. One for fuel and one for oxidizers, if needed.

[SharkWhisperer]

Very helpful! As always! So if I use Eastern Red Ceder shavings the charcoal chunks won't be very large. So if I add the charcoal as is with the other components do I need to mill for any extra time? Maybe 9 hours instead of 8 to make sure that charcoal gets crushed?

HF Rock Tumblers: You'll need to check specs on the motor size/capacity--this is my un-investigated impression, largely taken as memories from other pyro descriptions. Regardless if the motors are identical, they are both "light-duty" mills, but exceedingly functional, and, in my case, long-lived without burning out belts.

 

Milling Media, Times, and Charcoal tidbits: It's all empirical. Lloyd S has made available exhaustive milling specs and requirements for optimization. Super useful--dude's the man on the topic. But you're not secretively working on the Manhattan Project II, and don't (for now) require those specifically optimized milling parameters to get fantastic BP. Read his (and others' stuff, and learn from it though, particularly because you'll likely be building your own mill in a year or two, or sooner:+} Short answers: Milling media: 3/8" stainless is fantastic if that's what you have. 2) Milling time is empirically determined; my HF mill makes badass BP within 4 hours, but is notably faster with longer milling, up to perhaps 12 hours. This depends on spin rate, media size and type, and starting chems. You will quickly dial this in. Run it 4 hours, burn test a sample, run it 2/4 more hours, burn test another sample...get it? 3) Your ERC coal made from chips is almost powder already to start with; I've never ever needed to pre-mill it before mixing with nitrate and sulfur (and maybe dex) to spin out the final product. Charcoal isn't so tough, especially when made from chips instead of kindling-sized solid pieces. With willow branches that I retort to charcoal, I put them in gallon zip-locks and beat on them a bit with a hammer or whatever else happens to be at hand. Not aiming for powder (though that's what you mostly get) but for chunks less than a half inch or so (uh, 12.7 mm for our Euro crew) in largest dimension, for ease of handling. It can be messy business, to be done outside only, lest you yearn for a tv career on Divorce Court, or, if younger, want your Mom to boot your ass out of the house before fledging is complete, tsk tsk!

 

You will possibly amaze yourself with how simple the whole process is after you've done it once. You can't mess it up too badly. It's cheap, cheap pet bedding. Costs less than a dollar for a gallon can full of it; probably a quarter actually, if you buy a big bag. If you mess up, just learn from it and do it again. An hour of your life wasted and gone forever, shame! You're gonna laugh at how simple it is to make hot ERC charcoal, and hot BP, with a few minor considerations. Please do not be angry or exaspirated with your mortar and pestle---they served you as well as they could, and the will have usefulness down the road, too!!

 

And keep an eye out for willow trees--big ones often have a lot of dead branches laying about, which is just free, hot BP base.

[justvisiting]

@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.

 

a_bab, I have a little CMC observation I made that you might find useful. Since you don't mind to use water, 70% isopropyl (rubbing) alcohol, and CMC in your powders, you may want to try a hybrid method. I took 180 ml of 70% rubbing alcohol, and stirred 18 grams of CMC powder into it. The particles didn't dissolve or agglomerate. I stirred in 50 ml of water, and got no solution. I added 20 ml more water, and got 'some' thickening. I added a final 20 ml of water, and the CMC dissolved perfectly, producing a solution about the thickness of corn syrup. That's around a 7% solution. The thickening and dissolving when the final dose of water was added was almost instantaneous.

 

I haven't done anything with the solution, but I've stored it for a few months with no change to it. I've done quite a few BP experiments. I've always found that screen-granulated BP is faster than pucked, corned BP. Pucked BP requires no added binder for durability. Screen-granulated BP will easily crumble back to powder if made with 99% isopropyl alcohol. The grains will have more durability if 70% alcohol is used, because the potassium nitrate is able to dissolve to some degree and cement the grains a little. I wrote an article about using CMC as a binder, to make serviceable lift using commercial airfloat charcoal. It's around here somewhere. In that group of tests, I used only (hot) water. I used the CMC at 3% and got pretty durable grains. I did the experiment in response to a statement that commercial airfloat charcoal could not be used 'as is' to make BP lift, by screen-granulating a mixture of milled potassium nitrate, sulfur, and airfloat (with no further milling). I can link to the article if anybody is interested.

 

I would expect that preparing a CMC solution as I did above (but maybe 10% CMC), and using that to granulate your BP would be advantageous. You'd get less dissolving of the nitrate in the first place, and faster drying, which would reduce the size of any crystals that might form. Just a thought. I meant to try it, but never got to it yet.